Overheating on uphill slopes (again)

[DaraSue]

So on my way down to Vegas from SLC a couple weeks ago, the temperature was creeping up to, but not over the 220 line going through the mountain passes in central UT. It would cool back down on the downhill side or (I assume) when the fans came on.

Today I drove from Vegas to Oceanside, CA and noticed more of the same going through the hills along I-15 around Elsinore and Temecula. From the 15 to my cousin's house (back roads climbing up the hills from the Gopher Canyon Rd exit) it was hovering close to the 220 mark, and got a little bit over a few minutes from her house (about one or maybe a little over one needle width). I forgot to check the fans with it running but the radiator was cold.

Since buying the car I've had the thermostat it came with replaced, then replaced the replacement thermostat with a DMC one, had the coolant lines and pipes by the intake manifold replaced, had the cooling system flushed, had a kinked coolant hose replaced and replaced several clamps.

There's no apparent leakage from the lines. Is there something else I'm missing? Would a damaged overflow bottle cap account for any of this? Months ago, while trying to troubleshoot the original overheating issues, I set it on the square part of the door frame, thinking that I wouldn't be able to close the door and drive off without putting it back on. And well, you can imagine what happened next. It doesn't look visibly damaged but could it not be venting/sealing correctly or something? It's as if the coolant can't flow uphill, somehow, or the thermostat won't open when the car is pointed uphill.

[Gregadeth]

Is your otterstat facing the correct way (down towards the ground)?

[DMC-81]

Hi Dara Sue,

Based on it doing the overheating uphill and during which the radiator is cold, I would guess that you have air in the system. I would ask your mechanics whether they followed the correct procedure. The system needs to be bled at the radiator and the engine, preferably with the car elevated in the rear.

[Nicholas R]

Hi Dara Sue,

Based on it doing the overheating uphill and during which the radiator is cold, I would guess that you have air in the system. I would ask your mechanics whether they followed the correct procedure. The system needs to be bled at the radiator and the engine, preferably with the car elevated in the rear.

I agree, especially with all of those parts constantly being replaced, I'd imagine you've got air. You have to bleed at the radiator and at the engine. Do you have the auto-bleeder kit for the engine? Definitely something to consider.

[David T]

I agree, especially with all of those parts constantly being replaced, I'd imagine you've got air. You have to bleed at the radiator and at the engine. Do you have the auto-bleeder kit for the engine? Definitely something to consider.

Agree with rebleeding. On initial fill you must loosen the small hose on the top, right side of the radiator to get most of the air out after pressurizing the system. I would also replace the otterstadt switch. Good question on it's orientation. It it is the older style, installed on top of the pipe, you should update it. Other things to check, do both fans run, do they both run in the right direction (pulling air front to back) are the fan blades firmly attached to the motor shafts. Do you have the uprated circuit breaker for the cooling fans. Do you still have the fan fail relay or was it bypassed?

[Bob635]

A number of cars experienced this same significant engine temperature increase going up to Mt. Charleston at DeLorean Weekend 2 years ago. Temperatures were in the 80s and the slope was 2-5%. All of these cars were in apparent good condition. But some got much hotter than others.

So what does this mean? Engine/cooling system temperature is a function of two thing.- Waste heat generated from the engine and cooling effectiveness of the radiators and fans.
Assuming the waste heat from the engine is a constant (same mpg), this leads to the radiator and fans as the possible cause. However, one unknown is the efficiency of the water pump. This efficiency can very by the pumps design and there have been so many different water pumps out there it is unknown which pumps move more water.

Heat transfer in the radiator is strongly dependent on the cleanliness of the metal surface on the inside of the radiator. If this becomes coated with deposits - as all radiators do with age- the heat transfer efficiency of the radiator decreases. I have seen D cooling systems work remarkable well and others that have the same appearance work very poorly.

So you need to ask two questions.
How old is the radiator and how well has the cooling system been maintained?

On older cars, we used to flush the cooling system with Oxalic acid that would dissolve desposits inside the radiators. This would improve the cooling capacity but certainly not as much as a new radiator.

But what if you have a new radiator?
Well, then this points to the fans as the possible problem. At the fans original? How many amps are they drawing? If the bearings are dried out, they will draw more amps and not run as fast and consequently will move less air.

There are a number "replacement" radiators and fan combinations sold by various vendors. Unfortunately, there is no technical data or testing to confirm that any of these are better than the original system. Most claim "less amp draw" but say nothing about moving the same amount of air or cooling capacity.

In many cases, correcting this problem becomes a decision to just keep replacing parts.

Another old hot rod trick is to put a pusher fan in front of the radiator. This helps move air through it especially if you have AC.

One other thing that can be done to avoid boil over is to run 90% EG in the cooling system, This will raise the BP to well over 220.










So on my way down to Vegas from SLC a couple weeks ago, the temperature was creeping up to, but not over the 220 line going through the mountain passes in central UT. It would cool back down on the downhill side or (I assume) when the fans came on.

Today I drove from Vegas to Oceanside, CA and noticed more of the same going through the hills along I-15 around Elsinore and Temecula. From the 15 to my cousin's house (back roads climbing up the hills from the Gopher Canyon Rd exit) it was hovering close to the 220 mark, and got a little bit over a few minutes from her house (about one or maybe a little over one needle width). I forgot to check the fans with it running but the radiator was cold.

Since buying the car I've had the thermostat it came with replaced, then replaced the replacement thermostat with a DMC one, had the coolant lines and pipes by the intake manifold replaced, had the cooling system flushed, had a kinked coolant hose replaced and replaced several clamps.

There's no apparent leakage from the lines. Is there something else I'm missing? Would a damaged overflow bottle cap account for any of this? Months ago, while trying to troubleshoot the original overheating issues, I set it on the square part of the door frame, thinking that I wouldn't be able to close the door and drive off without putting it back on. And well, you can imagine what happened next. It doesn't look visibly damaged but could it not be venting/sealing correctly or something? It's as if the coolant can't flow uphill, somehow, or the thermostat won't open when the car is pointed uphill.

[DaraSue]

Thanks, everyone. The otterstat is installed facing down, although is the fact that it's zip tied a bad sign?

47721

The seller said he'd replaced the radiator, although he didn't say what brand the new one was. One thing I forgot to mention was that there was a lot of rust in the cooling system & engine block when I got it. At DMCCA they did a RedTek treatment to try and dissolve it, and there has been a noticeable reduction in the amount of crud in the coolant since the last flush, but could that still be gumming up the thermostat or radiator? (After: http://dmctalk.org/attachment.php?attachmentid=47178&d=1478460335 Before: http://dmctalk.org/attachment.php?attachmentid=46029&d=1472620289 )

My mechanic said he'd bled it after the flush and I called him just now to verify that he'd done the radiator bleed also and he said yes. He didn't think the temperature increase was anything to worry about as long as it didn't get above 230 and cooled down afterwards but it still makes me nervous that the radiator wasn't even warm.

I can't find any record from the seller or in my inspection report that the fans had been replaced but the updated relay kit was installed by the seller.

[David T]

Another thing to consider is the accuracy of the temperature gauge. They can be off especially if the motor was overheated. Do some checks with a non-contact infrared red temperature gauge. BTW, the fans should not really be the problem if you noticed high temperatures while moving over 30 MPH unless they are blowing the wrong way. At that speed you don't need the fans but they will run if you are running the A/C. You could also test the radiator cap to make sure it holds pressure. If you had a lot of junk in the system it is possible the radiator is partially plugged up inside. Maybe a reverse flush will help. In fact, I would suggest you reverse flush each part of the system, the motor, the rad, and the heater core. The radiator is designed to reject all of the heat the motor can produce. If it can't either the motor is making more heat than the radiator can handle or the radiator is plugged up or has air in it. Can't hurt to check the ignition timing. If it is off, it can cause the motor to get hotter than it should. Check the vacuum and mechanical advance too. How is your gas mileage? Last thing to consider, an overheating motor is a symptom of a blown head gasket. Test the coolant for combustion gases.

[DaraSue]

This is sounding like a bigger job than I want to attempt in my cousin's driveway, especially since her cat goes outside. :nervous:

I also called Jason at MW and he also thought it was probably an air bubble but while poking around under the hood I noticed some coolant above the water pump pulley so now I'm wondering if my mechanic's fancy t-bolt clamps aren't clamping again, this time on the hoses inside the thermostat housing...

47722

[Gregadeth]

Thanks, everyone. The otterstat is installed facing down, although is the fact that it's zip tied a bad sign?

47721No, it's good. It's a preventive measure so you don't lose your otterstat for good should it ever pop out of the coolant pipe.

[DMCVegas]

No, it's good. It's a preventive measure so you don't lose your otterstat for good should it ever pop out of the coolant pipe.

This. Since my Otterstat once popped out, I don't trust just the clip alone to keep it in place. I actually just use a hose clamp myself.

It's not unusual for your coolant temperature to increase as you climb hills since the engine is after all working a bit harder. And as long as it doesn't really go past 220, you'll be fine.

A couple things to keep in mind is that while pure water itself boils at 212°F, when you start adding chemicals to it such as antifreeze, as well as confine it inside of a pressurized space, it changes the properties of the water. Now as a coolant solution with a 50/50 mixture of antifreeze and water contained inside of a vehicle's cooling system, it will be good up to around 265°F before it boils out. Granted now you don't want to get that high of course, but around the 220°F mark is fine to operate at. Stick with the 50/50 mixture. Unless you're going to be in someplace with severe winter weather like Alaska or where the temp is going to go below -34°F (and yes, that is a negative), stick right at the 50/50 mixture. The the higher the concentration of antifreeze (aka ethylene glycol) you run in the car, the less efficient the car cooling system runs. Fine for those sub-34 temps where it's harder to warm up the car, but terrible for regular driving conditions elsewhere.

It's all the same principal as salting the roads: The sodium mixes with the water, and alters it's physical properties so that it melts at a much lower temp. It also lowers the boiling point too. Which is why you throw table salt into a pot of water when cooking. That way the water boils "faster". Or in this case, just at a much lower temperature.

The other thing is that most folks don't realize these kinds of properties of water/engine coolant. So if you look at your modern cars, they don't even print numbers on the gauges any more. They just say Cold & Hot. Plus they also have severe delays on how fast they report back. Unlike on old cars like the DeLorean where you get an instant picture of the temperature so you can see when your engine is running hotter on a grade, modern cars have delays so that you never see the fluctuation. Thus your other cars go through the same thing, but you'll never see it.

[Timeless]

Anyone use waterless coolant? Ive used it in many vintage vehicles I have owned and it works wonders. No water=no corrosion problem. Plus the boiling point is much higher than standard coolant and/or 50/50 mixed.

[DaraSue]

Well, I topped the coolant up with 50/50 and took it to a shop about 3 miles away. And apparently I should have had it towed, because now they're telling me the head gasket is blown. :banghead::banghead::banghead: I swear it never got above 180 on the way there and it had gotten at least one or two needle widths higher than it did last night once a day the whole way back from Chicago and was always fine after I stopped and let it cool for a while so I thought it would be OK to go a couple miles. :banghead::banghead::banghead:

I went back and checked the oil and the filler cap filter and they looked normal, but the shop owner said they'd done a chemical test that found coolant in the oil.

Trying to put a positive spin on it and tell myself that at least it didn't happen when I was in the middle of nowhere, but arrrrghhh. :banghead::banghead::banghead: This is the first time I've seriously wanted to cry and felt like I made a horrible mistake. Either by driving it to the shop or driving it down here or buying it in the first place.

:banghead::banghead::banghead::banghead::banghead:

[Rich]

About these points only:

Thanks, everyone. The otterstat is installed facing down, although is the fact that it's zip tied a bad sign?

One thing I forgot to mention was that there was a lot of rust in the cooling system & engine block when I got it. At DMCCA they did a RedTek treatment to try and dissolve it, and there has been a noticeable reduction in the amount of crud in the coolant since the last flush, but could that still be gumming up the thermostat or radiator?


As suggested the zip tie isn't a bad sign. Zip tying an Otterstat is a way to attach a newer o'stat that has a fatter flange on it. The OE o'stat spring clip retainer isn't big enough to hold one of those - it fits the original-size o'stats. You are OK until the zip tie ages out and breaks. Put a new sip tie on it annually if you want more peace of mind. If the Otterstat was bad then that's certainly a potential cause of overheating.

Rust isn't necessarily any problem as far as cooling capacity. The problem is if there are lots of bigger rusty flakes or any other debris/solids clogging the radiator tubes. Nice that it looks clear after the RedTek treatment. Not sure it proves that the radiator is fully functional, though.

Very unlikely the thermostat is clogged with anything. But it does need to fully open at its setpoint temperature - a failed-closed thermostat is certainly a potential cause of overheating. It's easy to test it after you get it out.

As David T. says, get a combustion gas test of the coolant to see if you are really facing a head gasket repair or not. The oil test indicating coolant in the oil isn't a good sign.

[DMCVegas]

Anyone use waterless coolant? Ive used it in many vintage vehicles I have owned and it works wonders. No water=no corrosion problem. Plus the boiling point is much higher than standard coolant and/or 50/50 mixed.

Waterless Coolant is useless. Pretty much just snake oil. It doesn't transfer heat as well as water does, so it runs higher internal temperatures in the cylinder heads and leads to more internal stresses and potential damage. Not to mention the price. Worst of all is that it can actually corrode aluminum. You don't see the problem as much in the older cast iron blocks, but in the modern ones it's fare more prevalent. We had a whole discussion on it over here. (http://dmctalk.org/showthread.php?14150-What-kind-brand-of-coolant-do-you-use/page4&highlight=waterless+coolant)



Well, I topped the coolant up with 50/50 and took it to a shop about 3 miles away. And apparently I should have had it towed, because now they're telling me the head gasket is blown. :banghead::banghead::banghead: I swear it never got above 180 on the way there and it had gotten at least one or two needle widths higher than it did last night once a day the whole way back from Chicago and was always fine after I stopped and let it cool for a while so I thought it would be OK to go a couple miles. :banghead::banghead::banghead:

Don't beat yourself up over it. It is a possibility that the car may have overheated before you got it, and the damage was already done. You CAN overheat an engine and not have a headgasket leak at that time, but it will severely shorten the lifespan of the gasket. It took 9 times before my gasket finally blew. But if it is blown, you can limp it along with a self-bleeder kit to get home just fine.

In the mean time, pull your oil filler cap and look down inside. Tell me which one of these photos it resembles

http://i1165.photobucket.com/albums/q593/DMCVegas/Oil%20Filler%20Necks_zpshovfl5ll.jpg

[DaraSue]

Maybe I've been looking at the wrong thing this whole time, but this was my filler cap: 47724 47725

The places where it looks white were just the flash, I didn't see any foamy stuff in it or on the dipstick.

I just called MW and talked to Jason who suggested bleeding it and checking it again before taking it for granted that the test was correct and taking the engine apart. I called the shop to tell them to do that but if the gasket really is bad I think I'm going to try and get a U-Haul and take it to Huntington Beach.

[David T]

Coolant in the oil can indicate leaking liner seals or a blown head gasket. Neither is good news but there is a BIG difference in what it will cost to fix. A combustion gas test of the coolant is next to confirm a head gasket leak. It will not rule out a liner seal leak though. There is no definitive test for the liner seals. If that is suspected the best thing to do is replace them and that is a much bigger job than just head gaskets. At that point it is worth considering a crate engine, or even a Stage II engine. If enough coolant got into the oil you are looking at bearings, pistons, rings and liners. A little unusual for a liner seal leak on the PRV in a Delorean. Blown head gaskets is the more common failure from overheating. Is there any sign that the heads were ever removed in the past? If there is, then a liner seal leak becomes more likely.

[DMCVegas]

Maybe I've been looking at the wrong thing this whole time, but this was my filler cap: 47724 47725

No, no. You need to look DOWN into the oil filler to examine that screen. Give us a photo down there.

For refernce, here is the difference between oil caps on a good engine, and one that has blown it's head gasket:

http://i1165.photobucket.com/albums/q593/DMCVegas/Oil%20Caps_zpsbozpy7yb.jpg

[DaraSue]

Rereading my posts, I said it backwards. They said it was the other way around, that there was oil in the coolant, if that makes a difference. The car is at the shop but I'll see if I can get over there to look at it again and double check what test they did.

David has mentioned that there might be a degradation in performance and gas mileage and I hadn't noticed any prior to yesterday (I think I'd gone over 100 miles since my last fillup and was only down 1/4 tank) so I'm hoping that means it hasn't been going on long enough to trash the engine.

[DMCVegas]

Rereading my posts, I said it backwards. They said it was the other way around, that there was oil in the coolant, if that makes a difference.

Is this an automatic transmission? Are there any oil coolers tied into your cooling system?

[DaraSue]

Is this an automatic transmission? Are there any oil coolers tied into your cooling system?

It's a 5-speed. No aftermarket oil coolers that I know of. The seller replaced the radiator and coolant bottle.

[David T]

It's a 5-speed. No aftermarket oil coolers that I know of. The seller replaced the radiator and coolant bottle.

The white froth on the bottom of the oil breather indicates water (coolant) in the crankcase. A bad sign and can be either a blown head gasket and/or a leaking liner seal. Oil in the coolant is another bad sign and indicates a blown head gasket. Your shop should proceed slowly meaning they need to carefully examine things as they take the motor apart but even before that some testing is in order. For instance you should do a leak-down test and a compression test. "Read" the spark plugs, do a combustion gas test on the coolant. Pressure test the coolant system and try to determine if coolant is leaking into the crankcase from the liner seals. As the heads are removed they should be careful to preserve the head gaskets as much as possible and be alert for signs that the heads were previously removed. Once the heads are off examine the cylinder walls, piston tops, and top edge of the liners for any signs of movement and measure the "nip" (liner protrusion above the deck of the block). At this point a judgement has to be made as to whether to do liner seals or not. One choice would be to "just" do the heads and cross your fingers and hope the liner seals are OK. You take the chance of "wasting" a head job. Here is where the knowledge, experience, and training of the mechanic is most necessary BUT few shops besides the Delorean vendors have enough knowledge and experience to make an informed decision on a PRV-6. The "safe" choice is to just do the whole motor but that is the most expensive option. If the PO replaced the rad and tank we can assume he had overheating problems too. Probably why the heads are "popped".

[DaraSue]

The white on my cap filter in the pictures isn't actually there - it's glare from the flash. But when I went back and looked down the filler neck, I found something odd:

47729

It doesn't even look like there was ever anything there, and AFAICR it's been that way ever since I've had it.

I had AAA tow it to Huntington Beach because the local shop didn't think they could fix it. Expect an update on Monday...

[DMC5180]

Danny at DMCCA will tell you if there really is a problem a head gasket. I would not trust that other shop. If you had oil in the coolant you would likely be able to see it floating in your header bottle. Use your phone camera with flash ON and take a pic with the lens sitting on top of the filler neck. Also, when your out driving and have a concern about what the Temp gauges indicates, snap a quick photo of it. Driving up long grades in 80+ heat with presumably A/C running adds heat load to the radiator. As for the leak you highlighted in a previous Photo, it's likely a loose clamp at the water pump or behind it at one of the two hose couplers under the intake manifold. I'm not sure what that thing is in your Oil filler neck. It looks like a crown type expansion plug that someone dropped over the screen. Its worth having DMCCA look at it to figure out what was done there.

[DaraSue]

Danny at DMCCA will tell you if there really is a problem a head gasket. I would not trust that other shop. If you had oil in the coolant you would likely be able to see it floating in your header bottle. Use your phone camera with flash ON and take a pic with the lens sitting on top of the filler neck. Also, when your out driving and have a concern about what the Temp gauges indicates, snap a quick photo of it. Driving up long grades in 80+ heat with presumably A/C running adds heat load to the radiator. As for the leak you highlighted in a previous Photo, it's likely a loose clamp at the water pump or behind it at one of the two hose couplers under the intake manifold. I'm not sure what that thing is in your Oil filler neck. It looks like a crown type expansion plug that someone dropped over the screen. Its worth having DMCCA look at it to figure out what was done there.

It doesn't really show in that pic, but the metal thing inside my filler neck slants downward toward the driver's side, if that means anything to anyone.

When it got over the 220 line this time, it was only about 60F out and I didn't have the a/c on (don't think I had it on during any of the previous incidents, either) but I'd been driving up fairly steep hills for about 20 minutes.

It was only about 1 needle width over the 220 line this time, although it got up around 230 for a couple minutes on the trip back from Chicago.

Leaking hose in the thermostat housing was my first thought too since I've had problems with that before and I let my mechanic talk me into replacing the clamps on the new hoses with t-bolts, and I've had problems with leaks on almost all the ones on the other hoses and ended up putting the worm drive ones on instead.

The one bright spot, at least the local place didn't charge me anything for looking at it...

[DMC5180]

There is a deflector (splash shield) attached to the inside of the rocker cover. Perhaps that is what we see in the photo. Regardless, it is very clean with no indication of contamination.


Sent from my iPhone using Tapatalk

[DMCVegas]

The white on my cap filter in the pictures isn't actually there - it's glare from the flash. But when I went back and looked down the filler neck, I found something odd:

47729

It doesn't even look like there was ever anything there, and AFAICR it's been that way ever since I've had it.

Yep. Your engine was overheated before you purchased your car.

As you can see in that first photo I posted, there is supposed to be a plastic screen in the oil filler cap. One of the things that Don Steger warned me about when purchasing a car was to specifically look for that screen. It's made out of a very soft translucent plastic. The first time an engine overheats that screen will turn white as it deforms and melts. So if you see an engine without that screen, it means that the engine has overheated previously. And once a car overheats, you're going to have internal problems with your engine. They may not be major right away, but at the very least the lifespan of the head gasket will be severely shortened.

Now I can't say that the person who sold you the car lied to you about it's condition and history. They may not have been a DeLorean expert to know about the screen. It's one of those little, hidden quirks. On the other hand, the question of overheating may not ever have come up.

In any case, I wouldn't blame yourself here. It's disappointing, I know. But it's not the end of the world. It is repairable.

[jamesrguk]

Yep. Your engine was overheated before you purchased your car.

As you can see in that first photo I posted, there is supposed to be a plastic screen in the oil filler cap. One of the things that Don Steger warned me about when purchasing a car was to specifically look for that screen. It's made out of a very soft translucent plastic. The first time an engine overheats that screen will turn white as it deforms and melts. So if you see an engine without that screen, it means that the engine has overheated previously...

I didn't have that screen on my stock DMC engine when I bought the car in '99, I did actually overheat that engine after about 9 years of ownership due to a split in the coolant jacket. But also I didn't have one on the B28E Volvo engine I installed a couple of years back and that was from a very tidy Volvo with a full dealer service history etc... and the internals looked amazing.

Presumably if it melts and goes inside the head it would get mushed up by the cams but surely even after 1000's of miles if you pulled the heads there would be some evidence of the remaining plastic?

I had the valve covers off my Volvo and original DMC engine with no evidence of any debris in there, which makes me strongly suspect that neither of these engines ever had the plastic gauze fitted.

It would be interesting to see how many DMC owners are missing this part.

James

[SamHill]

I am an obsessive temp gauge watcher. If it moves,I clinch. Any other car with an iron block... you can have a number of mess ups. When you see a D's needle climb past halfway, it's time to panic, cry and denounce the almighty. Which is to say I don't think overheating/immediate shut down is stressed enough in the community, much like the flammability of our underbodies.

[Bitsyncmaster]

My car has the plastic screen. I would not think anyone would remove the screen for any reason. But every car I've owned, the oil fill always is open to the valve cover without any screen.

[DaraSue]

I'd just had it in the shop a month ago and had the intake manifold taken off and the valve cover gasket replaced and some coolant pipe replacement. My mechanic didn't mention anything about the head gasket potentially being bad, and isn't that something you'd notice on a job like that? I'm 99% sure that screen thing was gone before then. I don't even remember seeing it right after I got the car, and I had it inspected at DMCMW and they seemed to think it was pretty solid. :confused0:

[David T]

I'd just had it in the shop a month ago and had the intake manifold taken off and the valve cover gasket replaced and some coolant pipe replacement. My mechanic didn't mention anything about the head gasket potentially being bad, and isn't that something you'd notice on a job like that? I'm 99% sure that screen thing was gone before then. I don't even remember seeing it right after I got the car, and I had it inspected at DMCMW and they seemed to think it was pretty solid. :confused0:

You would not remove the heads unless you suspected a problem. Sounds like the other work was just to fix some minor leaks. Did you tell him the car was overheating and you saw oil in the coolant?

[DaraSue]

You would not remove the heads unless you suspected a problem. Sounds like the other work was just to fix some minor leaks. Did you tell him the car was overheating and you saw oil in the coolant?

It was after the trip back from Wendover, when it had been leaking from the thermostat housing at a rest stop halfway back and I got it towed the rest of the way home. My temp and volt gauges were intermittently going dead so I can't be sure it didn't overheat that time, but as far as I could tell it only seemed to be leaking when I stopped (coolant wasn't noticeably low, no observed antifreeze trail leading up to my parking space, no smoke). I can't remember exactly what I told the mechanic but I'm sure I mentioned the possibility that it had overheated, if he couldn't figure it out on his own.

He had everything far enough apart to suggest I replace the valve seals and was trying to sell me on an overhaul that iirc would have involved taking the heads out, but Mike at MW didn't think it was really necessary right then since my car wasn't badly smoking or burning oil and he'd seen numerous cases of D engines being screwed up by shops that weren't experienced in working on them.

What exactly does oil in the coolant look like? I've never personally observed anything in there besides the previously mentioned rust.

[DMC5180]

Oil in coolant, think of it like pouring hot water in a frying pan after making bacon. Oily globules floating on the surface.




Sent from my iPhone using Tapatalk

[DMCVegas]

I didn't have that screen on my stock DMC engine when I bought the car in '99, I did actually overheat that engine after about 9 years of ownership due to a split in the coolant jacket. But also I didn't have one on the B28E Volvo engine I installed a couple of years back and that was from a very tidy Volvo with a full dealer service history etc... and the internals looked amazing.

Presumably if it melts and goes inside the head it would get mushed up by the cams but surely even after 1000's of miles if you pulled the heads there would be some evidence of the remaining plastic?

I had the valve covers off my Volvo and original DMC engine with no evidence of any debris in there, which makes me strongly suspect that neither of these engines ever had the plastic gauze fitted.

It would be interesting to see how many DMC owners are missing this part.

James

Every original DeLorean I've ever seen that has NOT overheated has that screen. Now perhaps the B28E had a revision by Renault for that screen, I don't know. But what I do know is that not only did a factory-trained DeLorean mechanic with decades of experience warn me about that piece, I've also seen it with my own eyes.

The engine on the left is the one that came with 6585. That engine when I got the car looked *exactly* like the one on the right. The one on the right is a spare engine I purchased from another DeLorean owner that came out of a low-mileage DMC-12 that was totaled and parted out. I had a really bad history of my car overheating when I first got it. The damn alternator blades were bent, so every time I went above 4,800 RPMs they would flex out and chew up the belt until it ripped apart.

It was at that point the translucent plastic turned white as it started to melt. It doesn't drip down, it just warps back and melts into the edges. I threw that piece of plastic away a long time ago, but I did witness the change first hand, just as Don said it would occur. The plastic is nasty, and if for no other reason that you're worried about it falling down the next time you do an oil change, it gets pulled. Otherwise there is never any reason that someone would have removed that screen.

[PJ Grady Inc.]

The white on my cap filter in the pictures isn't actually there - it's glare from the flash. But when I went back and looked down the filler neck, I found something odd:

47729

It doesn't even look like there was ever anything there, and AFAICR it's been that way ever since I've had it.

I had AAA tow it to Huntington Beach because the local shop didn't think they could fix it. Expect an update on Monday...

A missing screen normally means head gasket trouble provided you can see signs that the screen melted onto the oil splash plate below the filler tube. I don't see that here as the plate looks very clean. It is possible that your screen was simply pushed down too far into the neck, by an oil can filler or some other means, and fell onto the oil splash plate and is just out of view. I say that because there is no sign of the melted screen remains which would look like the first pic in post #15. Poke around the downward side of the baffle plate to see if you can retrieve the screen. If you find it check for deformation and if undamaged put it back into the filler tube. I've seen dislodged screens on a few PRV's before. That would be good news as then it is possible you don't need head gaskets but it's time for a cylinder leakdown test to determine your engines general internal condition and to pinpoint any internal cause of overheating.
Rob

[DaraSue]

I just heard back from Danny at DMCCA and he couldn't replicate the overheating issue but he thought it was sediment in the block and clogging the radiator. He wants to pull the heads off and clean it out. Mike had thought that might be a possibility too so I'm just going to have them do it. Guess as long as they're in there they might as well do the valve seals too.

Not exactly the outcome I was hoping for, but if it needed to be done, better now than in the summer, especially since I was hoping to drive it back east this spring.

[David T]

The radiator and heater core should be reverse flushed too. As long as the heads are off the valves should be "cleaned up" and lapped in.

[DaraSue]

A missing screen normally means head gasket trouble provided you can see signs that the screen melted onto the oil splash plate below the filler tube. I don't see that here as the plate looks very clean. It is possible that your screen was simply pushed down too far into the neck, by an oil can filler or some other means, and fell onto the oil splash plate and is just out of view. I say that because there is no sign of the melted screen remains which would look like the first pic in post #15. Poke around the downward side of the baffle plate to see if you can retrieve the screen. If you find it check for deformation and if undamaged put it back into the filler tube. I've seen dislodged screens on a few PRV's before. That would be good news as then it is possible you don't need head gaskets but it's time for a cylinder leakdown test to determine your engines general internal condition and to pinpoint any internal cause of overheating.
Rob

I didn't get a chance to look at it again after it went to the shop, but is that something they should find while doing the head and valve work?

(Edit: actually my local mechanic had the whole top of the engine off so it might be long gone.)


The radiator and heater core should be reverse flushed too. As long as the heads are off the valves should be "cleaned up" and lapped in.

They're probably just going to have to replace the radiator if it's as cruddy as it sounded like it was. Although it was supposedly new, so maybe it's still salvageable.

[iflights]

The radiator and heater core should be reverse flushed too. As long as the heads are off the valves should be "cleaned up" and lapped in.

Get the fans replaced at the same time they are replacing the radiator. Lesson learned.

[PJ Grady Inc.]

I didn't get a chance to look at it again after it went to the shop, but is that something they should find while doing the head and valve work?

(Edit: actually my local mechanic had the whole top of the engine off so it might be long gone.)



They're probably just going to have to replace the radiator if it's as cruddy as it sounded like it was. Although it was supposedly new, so maybe it's still salvageable.

They should check for a melted versus dislodged screen. I repeat "That would be good news as then it is possible you don't need head gaskets but it's time for a cylinder leakdown test to determine your engines general internal condition and to pinpoint any internal cause of overheating." I would not pull the heads before performing that test.
Rob

[DaraSue]

They should check for a melted versus dislodged screen. I repeat "That would be good news as then it is possible you don't need head gaskets but it's time for a cylinder leakdown test to determine your engines general internal condition and to pinpoint any internal cause of overheating." I would not pull the heads before performing that test.
Rob

I'll double check and see what kind of testing they've done, but the way he described it sounded like there was all that rusty sediment getting around the cylinders regardless of the condition of the head gasket and it would need to be cleaned out.

Maybe I should have had my local shop do all this when they already had the engine halfway apart...

[DaraSue]

Just talked to him again and yeah, he said the problem wasn't necessarily the head gasket but just all the rust and sediment getting around the cylinders and into the radiator preventing it from cooling properly. On straight aways it hasn't been any big deal but I kind of want to be able to drive my car uphill, and I was planning for a major road trip next year so hopefully this is the last major repair.

On the plus side I asked about the fans and he said those were new so they weren't likely to have been part of the problem.

[Chrisjohnsona4]

Thanks for this post, very informative for me at the moment, yet still am having some issues overheating. Maybe grab a cup of coffee before reading, I will try and go into as much detail as possible.

I recently went on vacation and experienced what I think was my car overheating. I drove to Pigeon Force from Charlotte, NC without having any issues, but noticed before I drove the car back home the car was very low on coolant so filled back up. Please note that I check the coolant level in my car before driving on long trips (and other times as well) as i've experienced this issue sporadically over the duration of time i've had the car (3 years).

A few days ago I was driving back from Pigeon Forge, TN on my way home to Charlotte, NC and after stopping at a gas station (which was about 30 minutes from my house), I noticed my temperature gauge very quickly started to increase past 220, and eventually topping out past the highest number. I immediately pulled over off the interstate and shut the car down, and you could hear what sounded like to be boiling water as well as coolant moving all throughout the hoses in the rear of the car, like swishing around in my engine compartment, didn't notice any smoking, and no signs of coolant anywhere, but the temperature gauge was off the charts. Keep in mind the temperature outside was a cool 44 degrees and rainy). After sitting for about 20 minutes, I cranked the car back up and the temperature gauge was sitting at 215-220. I proceeded to start driving again since the temp gauge seemed to start dropping some (the fans kicked on as the always do when increasing in temp)but after a 30 seconds or so it just increasing up again, but noticed the temp gauge this time was all over the place.. for example it would jump all the way up and then drop way back down to about 170-175 and then start to increase again, I ended up not wanting to gamble with it and decided to pull the car over and getting it towed home.

I checked the coolant the next morning, and noticed the bottle was completely empty. No signs of the coolant leaking onto the ground, or near the water pump. Also inspected the Oil Filter screen that you guys have been referring to, and mine is still intact. According to the invoices that the previous owner gave to me, the Delorean dealership in FL did close to $26K of work to the car, and the Head Gaskets were apart of the work done. This was work done late 2011 and 2012.

I drive the Delorean very frequently. I have noticed that this car will drive fine, through long trips, and short alone, but sometimes I get weird spikes on the temp gauge. Apart of my recent service (i'm at 50K miles) I recently did a coolant flush and purchased a new coolant bottle cap as the old one seemed to not hold 15 PSI as it used to. As a side note I have the auto-bleeder which was installed at the dealership according to the invoices I have.

Any ideas outside of what has been shared so far in this forum at what this could be? There is no coolant in the Oil, filter still is instact, no white smoking coming from tail pipes (no signs off a blown head gasket so far), i'm loosing coolant, but not sure where (it seems after driving long distances, whenever I turn the car off and back on, it looses coolant, perhaps as i'm driving it, because when it's stopped, there is no sign of coolant.. no idea where it's going). I've kept my car serviced regularly. I've followed the coolant flush procedures that were posted in the forums, the fans kick on each time the car starts spiking in temperature and no apparent signs of wear on the water pump. There is a little coolant under where the thermostat housing is, I did notice. The thermostat hasn't been changed since I owned the car. Also I don't believe the radiator has ever been replaced, but after inspecting seems to be in good condition and functioning.

Thanks in advance, and happy holidays to everyone. Hope someone can help point me in the right direction!

Chris

[PJ Grady Inc.]

Chris you obviously have an undetermined leak and are taking on air which will cause the symptoms you describe. The first area I would check would be to pressurize the cooling system and determine where the leak is. Most likely it is the two water pump hoses at the back of the pump that is causing your problem. If silicone hoses were not fitted there when the engine was rebuilt it is very likely the hoses have packed down and you will need to have someone enter the VOD and either tighten the clamps or better yet refit silicone hoses in that area. This problem is common and the valley holds a fair amount of coolant which gets spilled and burnt off as you drive the car and then the valley will fill back up on the cool down. If you can't get a pressure tester you could try jacking up the front end or park on a slope with the nose pointing up and let the engine cool down and see if coolant spills out the back as it cools down. The other cause of mysterious leaks is a bad coolant tank pressure cap which again will spill out as you drive the car but this time through the overflow hose. That would be a much simpler fix as you can just replace the cap. In either case your system will have to be bled at both the thermostat and the radiator once the leak is solved. If you have a self bleeder at the thermostat you will still have to bleed the radiator as it can trap air causing overheating as well.
Rob

I just caught this...."There is a little coolant under where the thermostat housing is, I did notice." You will be entering the "valley of death" in all likelyhood but try tightening all the accesable water pump and engine compt heater hoses first.

[Chrisjohnsona4]

Chris you obviously have an undetermined leak and are taking on air which will cause the symptoms you describe. The first area I would check would be to pressurize the cooling system and determine where the leak is. Most likely it is the two water pump hoses at the back of the pump that is causing your problem. If silicone hoses were not fitted there when the engine was rebuilt it is very likely the hoses have packed down and you will need to have someone enter the VOD and either tighten the clamps or better yet refit silicone hoses in that area. This problem is common and the valley holds a fair amount of coolant which gets spilled and burnt off as you drive the car and then the valley will fill back up on the cool down. If you can't get a pressure tester you could try jacking up the front end or park on a slope with the nose pointing up and let the engine cool down and see if coolant spills out the back as it cools down. The other cause of mysterious leaks is a bad coolant tank pressure cap which again will spill out as you drive the car but this time through the overflow hose. That would be a much simpler fix as you can just replace the cap. In either case your system will have to be bled at both the thermostat and the radiator once the leak is solved. If you have a self bleeder at the thermostat you will still have to bleed the radiator as it can trap air causing overheating as well.
Rob

I just caught this...."There is a little coolant under where the thermostat housing is, I did notice." You will be entering the "valley of death" in all likelyhood but try tightening all the accesable water pump and engine compt heater hoses first.

Thanks for the response. I am not under the impression that the engine was ever rebuilt. Could those silicone hoses crack, and cause the type of issue I am having? I plan on inspecting them this afternoon. I did notice that the cap that I was using wasn't holding proper 15 PSI pressure, so I found a cap off another vehicle that was holding about 16PSI and I put that on instead. Would that cause any issues, by installing a cap that is rated higher than 15 PSI?

Do you have the proper bleeding procedures for bleeding this car with the auto-bleeder installed? I am aware that the person that bled the car did not bleed it out from the radiator as well, so it sounds like I need to go through this process again.

I will also try and tighten all the accessible water pump and engine comps heater hoses first as you requested and will provide an update. This issue is just very sporadic, and mainly only happens on long trips. I went to check the coolant in the car the other day after my long trip and it took almost an entire gallon of coolant to get back to the half way mark in the coolant tank, which is pretty crazy.

[PJ Grady Inc.]

Thanks for the response. I am not under the impression that the engine was ever rebuilt. Could those silicone hoses crack, and cause the type of issue I am having? I plan on inspecting them this afternoon. I did notice that the cap that I was using wasn't holding proper 15 PSI pressure, so I found a cap off another vehicle that was holding about 16PSI and I put that on instead. Would that cause any issues, by installing a cap that is rated higher than 15 PSI?

Do you have the proper bleeding procedures for bleeding this car with the auto-bleeder installed? I am aware that the person that bled the car did not bleed it out from the radiator as well, so it sounds like I need to go through this process again.

I will also try and tighten all the accessible water pump and engine comps heater hoses first as you requested and will provide an update. This issue is just very sporadic, and mainly only happens on long trips. I went to check the coolant in the car the other day after my long trip and it took almost an entire gallon of coolant to get back to the half way mark in the coolant tank, which is pretty crazy.

Sorry about the rebuild reference...must have had that impression from another thread. Good quality silicone hoses don't normally fail. A 16 lb cap will not cause a problem. Did you test the cap with a pressure tester? If so how much pressure did it hold? You can lose a lot of coolant driving with a weak cap. Now that you have a good cap on it the increased holding pressure will amplify any other leaks you have so make sure you check all the hose clamps. To bleed the radiator you need either a pressure tester or you can simply warm the car up to operating temp and use the system pressure to facilitate the bleeding procedure. With the system pressurized simply loosen the small bleeder hose clamp at the top of the passenger side radiator tank and twist the hose around the nipple to break it free. Do not twist side to side, especially on an original radiator, lest you break off the bleeder nipple. If you do not see any coolant coming out you may have to back the hose partially off the bleeder to allow some coolant and any air to vent. If air is present the coolant will sputter and pop until all the air escapes. Even a small amount will make the car run hot as it disrupts the flow of coolant through the radiator. If your stars align you may solve all your issues with the new cap, tightening all clamps, and bleeding the radiator....a good way to start the new year!
Rob

[DaraSue]

Got my car back today, woohoo! So far so good. Stayed comfortably below 220 on the drive up the hill to my cousin's house, which was where I was having trouble last time. Cameron at DMCCA said that the sediment in the cooling system could have caused the radiator to stay cold if it wasn't circulating through the engine correctly. He said they hadn't found air in the lines, which was the same thing the shop in Rock Springs said when it was overheating on my way back from Chicago and I had the thermostat replaced. It's sounding like all that rust and crud in the system has been the root of most of my problems. They took it all apart and cleaned it out at DMCCA so crossing my fingers that this is my last massive repair for a while...