Cold/Warm start issues -- bad head gasket?

Greetings Oh-Knowledgeable-Ones!

I've had my D for almost 10 years. For the last couple it's had minor cold/warm start issues which have grown worse over time. Through troubleshooting I've checked out the thermotime switch / cold start valve, replaced the accumulator, replaced the ignition oil and checked electrical grounds / connections-- I'm sure that's not all but that's all I can think of at the moment. Still, after a few attempts it would always eventually start... until yesterday.

After trying to start it a few times yesterday, I got the car to idle at low RPMs as long as I held the accelerator just a tad. Then I noticed white smoke was pouring out of the exhaust.

Do you guys think this is a clear case of a bad head gasket? If that's the cause, then I guess it was making it hard to start in the past as it was a slow leak.

Thank you for the help here, I really appreciate it.

Bad head gasket..idk. Is the oil milky? How about light brown fluffy oil around filler cap? I don't think a bad head gasket would create hard starting like you are describing. I guess depending on how bad. Have you overheated the engine? That's the main cause for head gasket failure

Sent from my SM-G920R4 using Tapatalk

Quote:

---

Originally Posted by Ratrace427

Bad head gasket..idk. Is the oil milky? How about light brown fluffy oil around filler cap? I don't think a bad head gasket would create hard starting like you are describing. I guess depending on how bad. Have you overheated the engine? That's the main cause for head gasket failure

Sent from my SM-G920R4 using Tapatalk

---

The oil looked ok-- maybe a little bit thin. I didn't see any milkshake.

I have had to add coolant to the bottle from time to time.

The engine has not been overheated. I even added a second temp gauge to the car because I've been paranoid this might happen.

Having to add coolant could be a sign of a blown head gasket, or it could just mean that you have some leaks. Signs of blown head gaskets include:
Overheating
Blowing coolant out the overflow
Coolant in the oil
Signs of moisture in the oil fill

Your symptom doesn't sound like a blown head gasket, at least not yet. It is more indicative of the need for a tune-up. Worn spark plugs, bad ignition wires, worn dist cap/rotor, that kind of thing. The white smoke is troubling. That could be a problem. One test to confirm a blown head gasket is to test the coolant for combustion gasses. Or if it clears up quickly it might just mean you need a tune-up badly.

Quote:

---

Originally Posted by David T

Having to add coolant could be a sign of a blown head gasket, or it could just mean that you have some leaks. Signs of blown head gaskets include:
Overheating
Blowing coolant out the overflow
Coolant in the oil
Signs of moisture in the oil fill

Your symptom doesn't sound like a blown head gasket, at least not yet. It is more indicative of the need for a tune-up. Worn spark plugs, bad ignition wires, worn dist cap/rotor, that kind of thing. The white smoke is troubling. That could be a problem. One test to confirm a blown head gasket is to test the coolant for combustion gasses. Or if it clears up quickly it might just mean you need a tune-up badly.

---

Thank you for your help here.

In the last couple of years (and in the last 2,000 miles) I've replaced the spark plugs, distributor cap and rotor, spark plug wires, and had the injectors cleaned and personally tested their spray pattern. I've never checked / testing the timing...

So, two responses so far seem to me to say that the plume of white smoke coming from my tailpipe may NOT be a blown head gasket. Is that possible? I would assume there's not (within reasonable amounts) water in the tank as the car is garaged and only driven on nice days. What else could be going on?

I'm afraid to continue trying to start the car... I don't know what happening and I don't want to hydrolock the engine so at the moment I'm just information gathering. Do you know how I could "test the coolant for combustion gasses"?

Have you ever checked the mixture via a dwell reading?

How old is the gas?

Sent from my SM-G920R4 using Tapatalk

Running rich or lean will not produce white smoke. Crazy old varnish for gas might..

Sent from my SM-G920R4 using Tapatalk

I have not checked the mixture with a dwell meter. At this point I'm guessing I can't since it won't start up and run, right?

The car hasn't been driven enough, and the gas is a bit old. I don't think it's varnish yet though-- at least I hope not! I had about 4 gallons of.... 3 or 4 month old gas in it last time I drove it, and since I knew that was too old I had just filled it up a couple weeks ago with 4 more gallons of plus grade fuel. I know there might be more than one issue going on here at a time, but for what its worth the car still had trouble starting with fresher fuel.

It sounds a it counterintuitive but I've seen clouds of white smoke from the exhaust when the cat or muffler is full of raw gasoline. Which would be symptomatic of other fuel system problems. Shorted thermotime switch for example.

Quote:

---

Originally Posted by DMCMW Dave

It sounds a it counterintuitive but I've seen clouds of white smoke from the exhaust when the cat or muffler is full of raw gasoline. Which would be symptomatic of other fuel system problems. Shorted thermotime switch for example.

---

Interesting-- do you happen to know of the best way to test/check to see if this is a fuel system problem or a head gasket problem?

I've checked the resistances across the thermotime switch, and it checked out. Since it's warm outside now, I suppose I could disconnect it and try to start the car. I'm just worried about trying to start it if there's a lot of coolant or something in it and locking the engine up.

For what its worth, I've always had to periodically add coolant to the reservoir. I've also always known that if I fill it any more than 1/3 of the way full, it'll just blow out of the overflow-- never knew if that was normal.

I can drain the oil from the car and inspect it. If there's coolant in it, I wonder if I could notice if there's a separation of coolant and oil.

When I had a similar symptom (car would only stay running if I held the gas pedal down for the first few minutes) it was a combination of bad warm up regulator and flaky idle motor.

Maybe a dumb question, but what was the outside air temperature when you saw the smoke? I've never really idled the D at cold temperatures often/long enough to make a note of the quality/quantity of the exhaust but in my other car (87 CRX, carburated, ~280k miles), I've noticed the exhaust is definitely more visible when idling high in cold weather after a cold start. I'd always assumed that was standard car behavior? :confused:

Quote:

---

Originally Posted by DaraSue

When I had a similar symptom (car would only stay running if I held the gas pedal down for the first few minutes) it was a combination of bad warm up regulator and flaky idle motor.

Maybe a dumb question, but what was the outside air temperature when you saw the smoke? I've never really idled the D at cold temperatures often/long enough to make a note of the quality/quantity of the exhaust but in my other car (87 CRX, carburated, ~280k miles), I've noticed the exhaust is definitely more visible when idling high in cold weather after a cold start. I'd always assumed that was standard car behavior? :confused:

---

The WUR and the idle speed motor were next on my list to check out (when it was just a rough start issue)!

I'm in Texas so it wasn't cold... it was probably about 85 outside. When I say "white smoke" I don't mean like... a little. I mean... I couldn't see my neighbor's house. :jawdrop:

Quote:

---

Originally Posted by bluscreen

The WUR and the idle speed motor were next on my list to check out (when it was just a rough start issue)!

I'm in Texas so it wasn't cold... it was probably about 85 outside. When I say "white smoke" I don't mean like... a little. I mean... I couldn't see my neighbor's house. :jawdrop:

---

Yeesh, that definitely sounds like something is amiss. I don't remember that happening when I had my cold-start issues.:eek1:

Don't rule out the possibility that you're dealing with two separate problems that happened to occur at the same time, either. I've had that happen to me a time or two (coolant leak coincident with bad connector on temp & amp gauges was a big one).

Quote:

---

Originally Posted by bluscreen

Interesting-- do you happen to know of the best way to test/check to see if this is a fuel system problem or a head gasket problem?

---

Quick & Dirty: Pressure test the cooling system to see if there are any leaks. If there is something big, it'll show.

Slower but guaranteed: Send an oil sample off to Blackstone for analysis. They can tell you about the internal health of your engine, and if you are at the early stages of a coolant leak.

http://www.blackstone-labs.com/

Quote:

---

Originally Posted by bluscreen

I've checked the resistances across the thermotime switch, and it checked out. Since it's warm outside now, I suppose I could disconnect it and try to start the car. I'm just worried about trying to start it if there's a lot of coolant or something in it and locking the engine up.

---

You won't lock the engine up. Hydrolocking is when you submerge the engine and suck in liters of water at once that cannot be compressed. So it bends the connecting rods. Also, even with water in the oil, there is still oil lubricating the internal components. Granted you probably want to keep the driving to a minimal until sorted out.

Quote:

---

Originally Posted by bluscreen

For what its worth, I've always had to periodically add coolant to the reservoir. I've also always known that if I fill it any more than 1/3 of the way full, it'll just blow out of the overflow-- never knew if that was normal.

---

While that could be the symptom of a bad headgasket, it could also be the symptom of a bad radiator cap. If the spring or rubber on the cap has perished, it will squeak out tiny amounts of vapor as the engine is running, which will drain the coolant out. So the next question is how old is your radiator cap?

Quote:

---

Originally Posted by bluscreen

I can drain the oil from the car and inspect it. If there's coolant in it, I wonder if I could notice if there's a separation of coolant and oil.

---

The water may be emulsified in the oil, and will definitely be if you've warmed the engine up to temperature before the oil change. So it won't be like you see huge water droplets floating in the drained oil.

I will however give one word of advice: I don't know what kind of nasty chocolate milk, or milk shakes people grew up drinking, but oil from a blown headgasket looks nothing like that from my own experience. It definetely doesn't look normal, but it also doesn't look like a foodstuff. The color spectrum varies, so it may go from a dark brown, to a brownish/whitish pus color. If you have a bad headgasket, the one place you'll see it is your oil cap. There is a steel filter in the cap that filters the crankcase vapors before the enter into the intake manifold. That's where you'll really see sludge start to appear once it gets bad enough.

But to start, if you're concerned about a blown headgasket, do the oil analysis before you tear-ass into the engine so that you're not firing money blindly at this issue. Otherwise the other question is how old is your fuel? Because crap performance and white smoke seems to be the hallmark of sitting cars. For that, I'd dump a bottle of Techron in the tank, shake the car, and then burn through a couple of tanks of gas to see if you've got a change in performance.

Thank you Robert! These are good to know.

1) I'll look up how to pressure check the cooling system.

2) Good to know about locking up the engine. I knew it took a lot of water, but the smoke I was getting was... notable.

3) The radiator cap indeed was worn and didn't hold pressure. I replaced it about 6 months ago. I realize THAT change could prove to be problematic for the system which is used to a lower pressure.

4) So you can get white smoke (like in the amount I saw) from old fuel?


UPDATE: I added SeaFoam to the tank (as besides a cleaner, it's advertised as a stabilizer) and tried to start the car to give it a chance to work it's way around. To my astounding surprise, the car started right up from cold. The car hasn't started right up from cold in YEARS. I let it run for a bit in place, turned it off, and came out the next day and it started AGAIN without issue. So I drove it around a lot. Seems to feel a little laggy but was actually driving just fine. I didn't push it. I'm beside myself! I'd still like to check everything out though. Woohoo, today is a good day!

Quote:

---

Originally Posted by bluscreen

Thank you Robert! These are good to know.

---

No worries at all. It's not just that you're concerned about dealing with a potential headgasket issue here, but whenever you dealing with any problem you're having with a car, you just need to ensure that you go through the proper troubleshooting steps. For any single problem, there are always many different causes that could be responsible. Blindly wasting money on repairing what *might* be the culprit is the absolute worst thing that you can do.

Quote:

---

Originally Posted by bluscreen

1) I'll look up how to pressure check the cooling system.

---

The test gear is available from most any auto parts store through their tool loan programs, so you can borrow a set for free with a 100% refundable deposit. They also come with complete instructions as well. But long story short, you'll just screw the one end of the tester on to the overflow tank, and then just pump the whole thing up to around 14.5 PSI and then let it sit. A properly sealed system will maintain the pressure. You only need to test for about 5-10 minutes or so.

If the pressure holds, your cooling system is most likely fine. If you have a leak, the pressure will of course drop. If it's an external leak, you'll see it dribble on the ground (with the exception of the Y-Pipe in the VOD. Shine a flashlight down there to check), and if it's internal, then that's a sign that you've got a bad headgasket.

Anytime you perform a repair on the cooling system such as a water pump, new radiator, pipes, etc., it's a good idea to perform one of these tests before you start the vehicle up. That way you'll avoid any engine damage.

Quote:

---

Originally Posted by bluscreen

2) Good to know about locking up the engine. I knew it took a lot of water, but the smoke I was getting was... notable.

---

"Notable" is a subjective variable. For instance, in Vegas when I start my truck on a cold, 40°F morning, I get a puff of steam from my tailpipe that's about 4" or so before it rapidly dissipates thanks to the extremely low humidity. In Houston by contrast, because of the humidity I will see a steam trail of a couple feet shoot out.

Now when I finally fully blew my engine in Vegas on the DeLorean, yeah, I had a massive cloud that would just cover the entire back end of the car. Plus at that point I had other symptoms too like sludge and consuming almost a gallon of coolant a week as a daily driver.

Quote:

---

Originally Posted by bluscreen

3) The radiator cap indeed was worn and didn't hold pressure. I replaced it about 6 months ago. I realize THAT change could prove to be problematic for the system which is used to a lower pressure.

---

Nah, that shouldn't be a problem at all. The cooling system is designed to work under specific standards. Even if you had a lower pressure due to a bad radiator cap, that would not cause a long-term issue where the system suddenly became unable to cope with the higher, standard pressure. If there was a problem with leaks after you replaced the cap, that just means that the old cap was helping to hide an issue. The new cap would not have caused it.

Quote:

---

Originally Posted by bluscreen

4) So you can get white smoke (like in the amount I saw) from old fuel?

---

It's a possibility. Especially when it's a gray smoke due to an incomplete burn. Which is the other question still not answered: How old is the fuel in the tank? As fuel gets older, it starts to varnish, becomes thicker, and can gum moving parts up. Which helps to further cause a vehicle to run terribly, and can yes, potentially result in some smoke.

The other problem of course is that modern fuels have changed quite a bit over the past few years. For years MTBE was used as an oxygenator & octane booster (until idiot gas station owners helped cause it to be banned in several states by refusing to repair their storage tanks), and so now we rely upon Ethanol alcohol (despite it being less energy dense and decreasing performance). Now in the old days if you got some bad gas with water in it, you'd just dump in ethanol of some kind and it would get rid of the problem because it binds to water. That would help dilute the water through the entire tank, and you'd be fine. That's because gasoline is hydrophobic (rejects water), and ethanol is hydroscopic (absorbs as much as it can). But now we use ethyl as a way to oxygenate & cut petroleum fuel (up to 15% ethanol from the pump). That's (mostly) fine, but the problem now is that ethyl will just suck the water out of the humid air itself when exposed. That leads to phase separation that destroys the gasoline and won't let it run well.

But above all, know this: Ethanol blended fuels only have a shelf life of 3 months. After that, you need to dump the fuel and dispose of it accordingly. So you need to ensure that you're driving your car.

Quote:

---

Originally Posted by bluscreen

UPDATE: I added SeaFoam to the tank (as besides a cleaner, it's advertised as a stabilizer) and tried to start the car to give it a chance to work it's way around. To my astounding surprise, the car started right up from cold. The car hasn't started right up from cold in YEARS. I let it run for a bit in place, turned it off, and came out the next day and it started AGAIN without issue. So I drove it around a lot. Seems to feel a little laggy but was actually driving just fine. I didn't push it. I'm beside myself! I'd still like to check everything out though. Woohoo, today is a good day!

---

SeaFoam is alright. It and Techron are the ONLY two chemical additives I'd recommend pouring into the tank. Thanks to things like the rubber boot on the fuel pump and the O-Ring on the Primary Pressure Regulator back on the Fuel distributor, other chemicals (such as Chemtool) can actually do more damage than good. I found that out the hard way...

It sounds to me like you possibly had/have some gummed up components like the Cold Start Valve, and the SeaFoam helped clean them.

What I'd recommend next is to at least go ahead and burn through a couple tanks of fuel to get the old stuff out. Then see how it does. If you're still worried about a head gasket, or you see a loss of coolant, go ahead and do the following:

1. Pressure Test the Cooling System.
2. Run a compression test on each of the cylinders.
3. Send a sample of your engine oil off for analysis.

Even if you had just the tiniest of leaks that didn't show allot of steam, if any antifreeze is present in the engine oil, the analysis test of your oil will reveal it.

Good luck, and have fun enjoying your car! :)

Quote:

---

Originally Posted by DMCVegas

For any single problem, there are always many different causes that could be responsible. Blindly wasting money on repairing what *might* be the culprit is the absolute worst thing that you can do.

---

I wholeheartedly agree-- that's why I'm here. =)

Quote:

---

Originally Posted by DMCVegas

The test gear is available from most any auto parts store through their tool loan programs, so you can borrow a set for free with a 100% refundable deposit. They also come with complete instructions as well. But long story short, you'll just screw the one end of the tester on to the overflow tank, and then just pump the whole thing up to around 14.5 PSI and then let it sit. A properly sealed system will maintain the pressure. You only need to test for about 5-10 minutes or so.

If the pressure holds, your cooling system is most likely fine. If you have a leak, the pressure will of course drop. If it's an external leak, you'll see it dribble on the ground (with the exception of the Y-Pipe in the VOD. Shine a flashlight down there to check), and if it's internal, then that's a sign that you've got a bad headgasket.

---

Thank you for the write-up. I'll see if I can knock this one out this weekend!

Quote:

---

Originally Posted by DMCVegas

"Notable" is a subjective variable. For instance, in Vegas when I start my truck on a cold, 40°F morning, I get a puff of steam from my tailpipe that's about 4" or so before it rapidly dissipates thanks to the extremely low humidity. In Houston by contrast, because of the humidity I will see a steam trail of a couple feet shoot out.

---

"Notable" is used subjectively here in the same manner as "SeaFoam is alright." Like I said before, I'm not talking inches or feet of smoke-- I'm talking "can't see the neighbors house" kind of smoke. For something more precise it could described as a "billow approximately 20 feet wide by 20 feet tall by 10 feet deep at 85 F in around 40% humidity."

Quote:

---

Originally Posted by DMCVegas

It's a possibility. Especially when it's a gray smoke due to an incomplete burn. Which is the other question still not answered: How old is the fuel in the tank? As fuel gets older, it starts to varnish, becomes thicker, and can gum moving parts up. Which helps to further cause a vehicle to run terribly, and can yes, potentially result in some smoke.

---

If it's any help here-- I answered a couple posts back with "The car hasn't been driven enough, and the gas is a bit old. I don't think it's varnish yet though-- at least I hope not! I had about 4 gallons of.... 3 or 4 month old gas in it last time I drove it, and since I knew that was too old I had just filled it up a couple weeks ago with 4 more gallons of plus grade fuel. I know there might be more than one issue going on here at a time, but for what its worth the car still had trouble starting with fresher fuel. "

Quote:

---

Originally Posted by DMCVegas

It sounds to me like you possibly had/have some gummed up components like the Cold Start Valve, and the SeaFoam helped clean them.

---

Hoping that's the case! Still, the cold start valve was firing with a decent spray pattern, as were the injectors. Not to mention the car started up right after adding SeaFoam to the tank. I feel confident its a good product, but pretty amazing if it works before even making it through the system. =P Wondering if I just burned off all of whatever was "bad" the last time I tried (and failed) to start it.

Quote:

---

Originally Posted by DMCVegas

Good luck, and have fun enjoying your car! :)

---

Thank you; you too!


Will do some pressure testing and go from there! I'll post results~

Quote:

---

Originally Posted by bluscreen

"Notable" is used subjectively here in the same manner as "SeaFoam is alright." Like I said before, I'm not talking inches or feet of smoke-- I'm talking "can't see the neighbors house" kind of smoke. For something more precise it could described as a "billow approximately 20 feet wide by 20 feet tall by 10 feet deep at 85 F in around 40% humidity."

---

That is a rather large amount of smoke. Now if it is steam from a cracked head gasket, you're going to notice a sizable drop in your coolant level inside of the coolant bottle. In fact, it may even totally drain if you don't pay attention to it. But hey, at least that is a symptom with a measurable result that you can go by.

The other thing is that while steam is water boiling out, smoke is nothing more than unburned fuel. Just as an oil leak can lead to smoke (because the engine is trying to use it as a fuel), if your gasoline is bad resulting in an incomplete combustion for example, that can lead to smoke. Whenever you see someone in a diesel truck "rolling coal", you're actually watching diesel fuel just get dumped out of their exhaust pipe. Poking a hole in your fuel tank is the equivalent of rolling coal.

But getting back on track here...

Quote:

---

Originally Posted by bluscreen

If it's any help here-- I answered a couple posts back with "The car hasn't been driven enough, and the gas is a bit old. I don't think it's varnish yet though-- at least I hope not! I had about 4 gallons of.... 3 or 4 month old gas in it last time I drove it, and since I knew that was too old I had just filled it up a couple weeks ago with 4 more gallons of plus grade fuel. I know there might be more than one issue going on here at a time, but for what its worth the car still had trouble starting with fresher fuel.

---

Well, there are a few things to understand here before we go on. And I know this is going to be a read, but trust me, it's worth it.

Unless you are speaking specifically about a top-tier fuel that contains additional detergents or distillates to clean your fuel system (meaning name brand gasoline), there is no such thing as "plus" or "premium" grades when it comes to gasoline. They all meet the same minimal standards. Likewise, pure gasoline itself, no matter which pump nozzle it comes out of, always contains the same amount of energy. Octane ratings do not mean better fuel, nor does it mean more powerful fuel. All that Octane does is tell you the gasoline's resistance level to burning. High-performance engines with higher compression ratios will raise the temperature much higher on the compression stroke than ones used for economic driving. All so they can harvest as much power from the fuel as possible. But those higher temps can cause the gasoline to spontaneously combust before the spark plug fires. That's called pre-detonation, or pinging. So additives are introduced into the fuel to force it to resist catching fire like that. The measure of that flammability resistance is called Octane. So, the higher the Octane rating, the more difficult the fuel is to burn because it burns slower. That's because it now takes longer to heat all of the fuel up to that new, higher flash point temperature. So when you put a higher Octane fuel into a low compression engine like the DeLorean has, you can actually get decreased performance. Especially when dealing with gas that's already gone bad. It can also lead to an accelerated accumulation of carbon deposits in the combustion chambers.

I know, this problem gets especially confusing with the Owner's Manual. There are completely different measurement methods for calculating Octane ratings. The manual lists both RON for the UK (page 39), and what we have in the US, (R+M)/2 (page 40). Both methods deliver two different sets of numbers that pretty much mean the same thing. But with a stock DeLorean engine you ONLY want to use 87 Octane in North America.

The other problem is your fuel has probably gone bad. With pure gasoline, when it becomes exposed to air, it will deteriorate. Organic compounds will evaporate off, meaning that the fuel then becomes less potent, and doesn't burn completely. Then the fuel will also break down and become thick. Which is what people refer to as "gum" or "varnish". Even worse is how all this gets compounded with modern fuels utilizing Ethanol. Gasoline doesn't like water, but Ethanol LOVES it! (if you've ever had a cocktail, you know this) Where as gasoline really only gets water through condensation or direct contamination (flood water at the gas station for example), Ethanol will suck water right out of the humidity in the air. So if your fuel has been exposed to air resulting in it going stale, then you just know that it's also been sucking the water down.

That's when Phase Separation takes place. Here's a handy video:

https://www.youtube.com/watch?v=v1DPsNOCwaU
https://www.youtube.com/watch?v=v1DPsNOCwaU

As stated in the video, once the Ethanol separates from the Gasoline, you not only run the risk of stale fuel, but now you also have Gasoline with too low of an Octane rating. Which can cause pre-detonation, and a crappy running engine. Because before the gas varnishes, the Ethanol first separates from it and lowers it's Octane rating.

If I were to guess here, I'd say that the new fuel you put in probably helped absorb the existing water in the fuel to dilute the level of moisture and raise the octane a bit. From there the SeaFoam probably also added back in the volatile chemicals (what they refer to as "ignition vapors") to help increase the fuel's flammability, and helped emulsify the rest of the suspended water to help slowly boil it out. But with water, and SeaFoam in the tank, I'd say that with that you're still going to have some visible smoke. Vapor from the water, and also because SeaFoam is an oil that isn't going to burn completely.

Start with testing your Cooling System. If that passes, I'd go ahead and drain the gasoline out, and then run at least 2 tanks through. If the smoke still isn't gone, proceed with the compression test and see where you're at then.

Quote:

---

Originally Posted by DMCVegas

That is a rather large amount of smoke.

---

Indeed-- notable even! :)

Quote:

---

Originally Posted by DMCVegas

Now if it is steam from a cracked head gasket, you're going to notice a sizable drop in your coolant level inside of the coolant bottle. In fact, it may even totally drain if you don't pay attention to it. But hey, at least that is a symptom with a measurable result that you can go by.

---

Now that I think of it, the last time I filled the coolant reservoir was one of the first times I've filled the bottle up more than 1/3 of the way. It's back to 1/3 again, too. I wonder if filling it up past that point helps it to dump coolant into the engine somehow. Looking forward to the results of the pressure test.


Thanks for the write-up. I understand the meaning behind octane as well as the gas rating the DeLoreans typically prefer. I put a higher grade gasoline in for the last fill-up to help offset the lowered octane of the old (originally 87) gas in there. Coincidentally, the older gas may have been ethanol-free. There's a station a little out of the way that I try to frequent as often as possible that markets its gasoline as ethanol-free.

No, overfilling wouldn't cause an issue with damage the the cylinder heads, or the cooling system itself. Water isn't compressible, but air is. So the empty space of air inside of the cooling bottle can shrink and expand as the coolant expands and retracts with the heat cycles. If by chance you were to overfill the bottle and didn't give enough space for the coolant to expand, or even no space at all, it wouldn't hurt the system. That's because the Radiator Cap acts as a fusible link to prevent damage. As the pressure built up and pressed against the cap, it would slowly vent out coolant steam until the pressure went back down. Given that it's a closed circuit system with an external expansion tank (not an external overflow reservoir), you'd probably have to burp it after that to let some air in. But the fluid level should never change. We have an '07 F150 still running it's original coolant (I plan on flushing the system later this year), and for the 7 years of which we've owned it, the coolant level hasn't once dropped below it's cold level.

But when you say ⅓ of the way, are you saying that the coolant level dropped below ⅓ of it's capacity? Or that you simply keep adding ⅓ of coolant each time? As long as you keep the coolant about ⅗ full inside to cover the bottom, and to let the bleeder return pour in unobstructed, you'll be fine.

Quick question: Does your windshield ever get really greasy on it's own?

I didn't think "overfilling" it would hurt the engine. I'm just wondering if there's a correlation to this smoking-not-starting issue and the fact that I filled the tank more than usual.

As for 1/3 capacity question-- basically I'm trying to say that the bottle seems to stay at 1/3 capacity. If I fill it with more, it'll be back down to 1/3 the next time I check it. However, I've not seen it go lower than this.

Windshield greasy? No. Are you thinking of gas vapors from the filler? I've had my filler refurbished somewhat recently (well after any issues here) and I know it's not a perfect seal but I think it's OK. I have a locking gas cap that I will replace with the standard DeLorean non-locking and better-sealing at some point soon too.

You could wait and see if the fluid level drops more, but I'd for go for the compression test & oil analysis instead.

The reason I ask about the windshield is because of the heater core. It is possible to have a tiny leak there with the vapor escaping, but not dropping out. That too could be the cause of a leak. But the tell-tale sign of that would be a greasy windscreen on the inside. The water just evaporates, but the glycol sticks to the glass.

Results are in! When I pumped the DeLorean's coolant system up to 14 psi, it dropped 1 psi after 15 minutes, 2 more at 30 minutes, and 4 more at the 90 minute mark.

Thoughts? I think this sounds reasonable.

Even better, when I first pressurized it there was a small leak at the line that connects to the bottle. This might explain where the coolant has been going. A few turns of the worm clamp fixed the leak.

I also tried running the car with the pressure system attached (and not artificially pressurized). The car started with just a little bit of white "smoke" (smelled a bit like fuel) and after idling for about 5-10 minutes the pressure has risen to 2 psi. I don't know the norm, but I didn't want to leave it idling all day so I stopped there. I would imagine a head gasket issue could also drive the pressure up in this case too-- which thankfully didn't happen.

Upon doing some quick research on the internet about how long a car should be able to keep cooling system pressure, I did find an article about hydro-locking an engine and the warnings involved with it. If indeed you're leaking into a cylinder, it's not unheard of to compromise an engine this way.


At this point I'll need to do some serious driving to run this gas through the car. Then it looks like the task will be to see if it's still having trouble starting. If so, it must be the WUR or something like that. I should probably change the fuel filter and take a dwell meter to it as well.