Help.. Car all over the place after cleaning the VOD

[flux3d]

Hopefully you guys can help. Following stripping down the engine to reveal the VOD, and putting every back together after what turned into a far bigger job than I thought it would be (loads of "while in there" tasks") the engine is running all over the place, not to mention potentially overheating!

I stripped of everything to get to the VOD, only to find a coolant leak, and a water pump which was well past its best. Therefore I decided to do a few extra jobs while in there. They included:

paint the VOD after cleaning.
New water pump.
New cap, rotor and HT leads
New silicone hoses and Silicone Vacuum hoses.
Two new sensors in the Y pipe, just not the thermotime switch (none available).
New gaskets and o rings throughout.
Generally cleaned everything and gave quite a few parts a coat of high temperature paint.
New stainless bolts for everything.
Adjusted the valve clearances as well.

You'd think after all that turning the key should have resulted in a purring engine, but no. Instead after quite a few cranks of the engine it started, but the idle shot up to 2000 rpm and stayed there! The engine seemed to get VERY HOT very quickly, especially the exhaust. The exhaust seemed louder as well, and there was a smell of unburnt fuel.

In a bit of a panic move I decided to mess with the idle screw setting, which did bring the rpm down a little, but not to where it should be or was before I started the job. After that I did the worst thing possible and moved the screw back and forth without really taking note. Yeah I know, bad idea, stupid, you name it. Now it's probably way off.

Attaching a dwell meter as I did last year to set it up just produced a very odd reading. The needle just plants itself right to the right hand side and doesn't move at all. I'm not sure the frequency valve is functioning as it should as well. I can't seem to hear it at all except for one time when it seemed to be running all the time. I've checked the ground point for this on the manifold and that checks out.

I can't see where there would be any vacuum leaks. The injectors went back in ok, and everything else checks out. I'm pretty sure I put all the vac pipes correctly.

Also, even after burping the radiator and bleeding the water pump at the top the radiator stays fairly cold, while the engine seems very hot.

The car was running perfectly before I started and had never had an overheating problem. The rpm was spot on, as was everything else other than the major coolant leak in the VOD.

I really need some ideas. I'm moving out of this house on the 28th, and need the car to run so it can move as well! At this rate it'll become a permanent fixture.

Any ideas?

[David T]

Sounds like you have 2 principal problems, one is the overheating and the other is running way too rich.

Make sure you installed the thermostat correctly and that it is opening. Rebleed the air out of the housing and the radiator.

For the over-rich condition, make sure the cold start valve is not staying on. Recheck the hoses to the CPR. If necessary adjust the mixture screw, it may not have been right to compensate for vacuum leaks which you fixed while doing all of this work. Make sure the vacuum advance is working correctly. Check the spray pattern on the injectors.

[Totally 80s]

Probably worth asking if you got the "pipe of agony" all the way in. That could definitely cause a 2000 rpm idle.

[flux3d]

Hmmmm, that's a good point about the pipe of agony, although I did put a new washer in there and it was very tight fit to get it back in. Maybe it dislodged the rubber washer when I put it back in.

Yes David, I did wonder about the thermostat. Looking at the diagram on the delorean.eu site it seems fairly obvious how it goes together into water pump, but is there a nack, or an obvious thing I might have done wrong? Cracking open the bleed point on top of the pump fluid flows fairly well, just not a jet of water, more of a drain down the front of the pump. Is this an indication that the thermostat isn't opening correctly?

What about the lack of a correct reading on the dwell meter? Can it be THAT far out?

[Totally 80s]

Hmmmm, that's a good point about the pipe of agony, although I did put a new washer in there and it was very tight fit to get it back in. Maybe it dislodged the rubber washer when I put it back in.

Yes David, I did wonder about the thermostat. Looking at the diagram on the delorean.eu site it seems fairly obvious how it goes together into water pump, but is there a nack, or an obvious thing I might have done wrong? Cracking open the bleed point on top of the pump fluid flows fairly well, just not a jet of water, more of a drain down the front of the pump. Is this an indication that the thermostat isn't opening correctly?

What about the lack of a correct reading on the dwell meter? Can it be THAT far out?

Without knowing how much your cracking it open it's hard to say but it should definitely stream out, not dribble.

[flux3d]

Hmmm, I'm thinking there's something wrong with that thermostat maybe. I'm not sure the flow out is as strong as it should be.

[Mike F]

Sounds like you may not have gotten all of the air out of the system. Often times you have to bleed both locations a few times before all of the air makes it out. You can have a pocket of air in just the right spot to cause the water pump to be essentially ineffective. Here's a way to check that: once the engine is cool enough to remove the header bottle cap, start it up and observe the coolant inside. It should be obviously flowing. If not, you've still got air trapped in the system (assuming your water pump is functioning!). If that's the case, keep bleeding and filling; it should eventually work all of the air out. A similar situation happened to me when I did my VOD job. A few cycles of bleeding eventually took care of it.

[mluder]

I would definitely check the pipe of agony... If you remove and re-install it, put some silicone grease all over it to help ease insertion.

Here's something no one mentioned... You said you gave everything a couple coats of high temp paint... Have you checked your ground locations for continuity? There are several points where the various components come together that need to be bare metal to metal contact. There are also a few ground bolt locations that also need to touch bare metal. An interrupted ground loop could cause the car to idle high AND might also explain your dwell meetings.

I would start testing continuity between various locations. Start with a lead on the battery ground under the water bottle and start touching the other probe to various bolts around the engine especially the mass of ground wires on the back of the intake manifold.

Cheers
Steven

[mluder]

Sounds like you may not have gotten all of the air out of the system. Often times you have to bleed both locations a few times before all of the air makes it out. You can have a pocket of air in just the right spot to cause the water pump to be essentially ineffective. Here's a way to check that: once the engine is cool enough to remove the header bottle cap, start it up and observe the coolant inside. It should be obviously flowing. If not, you've still got air trapped in the system (assuming your water pump is functioning!). If that's the case, keep bleeding and filling; it should eventually work all of the air out. A similar situation happened to me when I did my VOD job. A few cycles of bleeding eventually took care of it.

Agreed... It can take a couple of cycles of bleeding to get all the air out. Ask me how I know.

Cheers
Steven

[Bitsyncmaster]

Agreed... It can take a couple of cycles of bleeding to get all the air out. Ask me how I know.

Cheers
Steven

+1
Many of my daily drivers are the same and require two or three bleeds.

[NightFlyer]

http://www.dmctoday.com/showthread.php?682-Coolant-Flush-and-Refill-Procedure-To-Avoid-Bleeding

[AugustneverEnds]

Sorry to hear about your troubles!

For your overheating problem, get a coolant system pressure tester. I've written this before but it's worth repeating because it makes things so much easier. No worrying about overheating the car before all of the air is bled out or the coolant level falls too low and you can test and see that all of your coolant hoses are leak free before you put everything back together. Again repeating myself but Autozone will loan you one for free so cost is not an issue :biggrin:

When you removed the intake manifold did you replace the O-ring seals? When you put your engine back together was the intake torqued down enough? As others have pointed out the pipe of agony is a good place to check.

[krs09]

I had to same issue when I went through my VOD. After I was done I fired it back up and my idle shot to about 2000rpms and stayed there. Nothing like rebuilding an engine and racing it to 2000rpms right off the bat. It turned out my thermister (in the Y pipe) got disconnected or I got a bad switch out of the box (purchased it brand new) and being disconnected the idle will scream. I had to jump 2 pins behind the driver seat to take the switch out of the system. As soon as I jumped the switch the idle came right back down to normal. I still have it jumped to this day.

[DMCMW Dave]

Great comment. We've seen one or two where you plug the thermistor in and the pin backs out of the connector shell. Acts just the same as you mentioned here. Very high idle, and if you try to pull the idle down mechanically it is very unstable.

[flux3d]

Thanks for all the advice guys. I'll try to answer each in turn:

Yep, I think I need to try and bleed the system better. I've rigged up a Y connector and tap at the small pipe coming off the radiator on the passenger side. Should allow me to bleed everything better.

The pipe of agony. Hmmm, something to check. I did put some grease on it before insertion, but maybe its pushed the new seal out somehow..... something to check for sure.

On the continuity and earth points, I made sure to mask off all of the mating parts of the engine, and for the two earth points on the manifold I I did file things down, but it wouldn't hurt to check these out. Am I right in thinking that the one on the right hand side is for the frequency valve, which might explain some problems.

Good point about the manifold being torqued down. I did it by hand to as tight as I could get it, mainly because the bolts are hard to get to. Does it need a high level of torque? Yes, I replaced the O rings as well. Maybe something to look at as well.

Now, the whole thing about the thermistor sound right on the money. It was the only sensor I didn't replace as I couldn't find one anywhere. Could this be the problem area? The other sensors came out of the Y pipe, but this one stayed in. What's more my helpful mate put it in the oven with the other parts to "bake" the paint without removing the sensor. could this have "baked" the sensor as well? If so, does it make much difference? I've read its supposed to create a temporary "high idle" on a cold start, which it rarely does. Does it matter, and can I just jumper it like you said?

Sounds like some excellent advice guys. Plenty to try out. I might strip it down to the vally at the weekend and try these out.

Mark

[Totally 80s]

Yeah, I'd say putting any electronics in a 350 degree oven would pretty much destroy them.

[Tillsy]

I'd say it's toasted - pun intended ;)

[krs09]

Thanks for all the advice guys. I'll try to answer each in turn:

Yep, I think I need to try and bleed the system better. I've rigged up a Y connector and tap at the small pipe coming off the radiator on the passenger side. Should allow me to bleed everything better.

The pipe of agony. Hmmm, something to check. I did put some grease on it before insertion, but maybe its pushed the new seal out somehow..... something to check for sure.

On the continuity and earth points, I made sure to mask off all of the mating parts of the engine, and for the two earth points on the manifold I I did file things down, but it wouldn't hurt to check these out. Am I right in thinking that the one on the right hand side is for the frequency valve, which might explain some problems.

Good point about the manifold being torqued down. I did it by hand to as tight as I could get it, mainly because the bolts are hard to get to. Does it need a high level of torque? Yes, I replaced the O rings as well. Maybe something to look at as well.

Now, the whole thing about the thermistor sound right on the money. It was the only sensor I didn't replace as I couldn't find one anywhere. Could this be the problem area? The other sensors came out of the Y pipe, but this one stayed in. What's more my helpful mate put it in the oven with the other parts to "bake" the paint without removing the sensor. could this have "baked" the sensor as well? If so, does it make much difference? I've read its supposed to create a temporary "high idle" on a cold start, which it rarely does. Does it matter, and can I just jumper it like you said?

Sounds like some excellent advice guys. Plenty to try out. I might strip it down to the vally at the weekend and try these out.

Mark

I would say its worth a shot. Just fire the car up like it is now and as soon as you make contact with the jumper it should come right down and settle in. I just used aligator clips and grabbed the pins while still in the connector (minimal mod) if that makes sense. If you make contact and nothing happens then you know you can move on and try something else. I just left it connected because I dont plan driving the car in ice cold weather and I havent had a chance to get back into the VOD just yet.