Starting Problems, Grey Smoke

[JabberWalkie]

So, I have a 1990 Subaru Legacy. It has problems starting when it has sat around for a day or two. When I try and start it the engine stalls when I let it idle and it blows a bunch of gray smoke. After I warm it up for a while it now starts perfectly, like nothing was wrong.

These are the following test I have done:

Compression test: Checked out. Nothing seems to be wrong.

Coolant levels are fine, they have not been going down.

Oil was really high, did an oil change and put the correct amount of oil in. Problem persists. Checked the oil for signs of coolant leakage, there were none.

Checked the plugs for anything odd, they seemed fine.

Checked transmission oil levels (some people suggested to me they might be burning) they were fine.

Did a fuel pressure test. Failed to hold fuel pressure after ignition was turned off. Problem was a faulty regulator, replaced it. It holds pressure now. The problem seemed to get worse after this......

So, after all this I think it is a problem with the fuel system...but I'm not sure what to do in order to pin it down. Any help would be appreciated.

Additionally, Here is a video that shows the symptoms....

http://www.youtube.com/watch?v=GRtfHi0G5xo

[evolutionmovement]

Looks like coolant to me. Doesn't look like it's running rich and it doesn't look like oil. Doesn't act like oil either. My GUESS is someone put too much oil in (you said it was high) and the pressure blew out some gaskets (probably head gasket). When the engine is cold, the coolant gets in, but when it heats up the gasket reseals and cuts off the coolant from entering the combustion chamber. It doesn't take much to put out a plume. Just Sea Foaming an engine can leave a smoke screen behind. That also might explain the low idle since the coolant doesn't like to burn as well as gas.

[Herm99]

Oil was really high, did an oil change and put the correct amount of oil in. Problem persists. Checked the oil for signs of coolant leakage, there were none.

If it was overfilled, you most likely dumped some oil down into the cats, if you're lucky they may dry out and be ok, but its possible they are already damaged beyond saving. And they will certainly blow some smoke out for some time, until it burns out at least.

Get a CEL yet??

[JabberWalkie]

Get a CEL yet??

No, not yet.

Looks like coolant to me.

Ok, well how can it be a head gasket if it passed a compression test? Also, if it is a small leak, how long would i have to run the car to notice the coolant level going down appreciably?

[evolutionmovement]

As above: it reseals at temp. It doesn't take much coolant to smoke. I've had head gaskets that pass compression tests often. In this case, it's a little different as it must be getting past the fire ring to get coolant in there, but the usual failure mode is to show no sign until the car starts to mysteriously overheat. What happens is combustion gases collect in the pocket for the water pump impeller until there's enough to deprive it of coolant. There will likely be no oil in the coolant and no coolant in the oil either. However, they don't smoke either. Doesn't mean there couldn't be a less common failure mode that does the opposite exchange when caused by a different source (high oil pressure).

Doesn't have to be a head gasket to cause it either, all that has to happen is for SOME gasket to have been compromised a little and reseal under heat. Head gasket's the only one I can think of where that would be likely. A cracked head could also do it, but you don't mention any overheating.

Oil smoke tends to be blue. That's way too much for valve seals and goes away like rings wouldn't. A bad HG could maybe do the same thing with oil or might be getting into the intake manifold, but that seems much less likely.

Overfueling could cause the same problems, but that tends to look black and has a very distinctive smell that you don't mention having. However, this is the other likely culprit as it also explains your idle and only happens under open loop conditions. But then overfilled oil wouldn't probably have anything to do with it. Check your O2 sensor.

[JabberWalkie]

Ok, so hopefully this will help narrow it down. I did a test to try and figure out which cylinder it was smoking out of. I started the engine for a few seconds, just so it smoked, then I turned it off and pulled the spark plugs to look for smoke. First two tries at this smoke came out of the left cylinders, but I continued doing this and was able to get smoke coming out of all of the cylinders (not at the same time). Can someone tell me what this could mean?

Thanks for the help guys.

[JabberWalkie]

Well, this is an update for anyone that cares to read it.

I started seeing bubbles in the coolant, that combined with the smoke I guessed there was a coolant leak into the combustion chamber. So, after much labor I took the engine out and replaced the head gaskets after i noted some possible leakage around the cylinders:

http://freenodephysics.googlepages.com/IMG_0311.JPG

Note the green deposits on the left lower region, around the cylinder. So, I thought that must be where the leak is, burnt coolant reside most likely. My dad suggested i get the heads resurfaced, so I did ( professional shop did it). These are the resulting heads:


http://freenodephysics.googlepages.com/IMG_0321.JPG

http://freenodephysics.googlepages.com/IMG_0322.JPG

I inspected the surface quite thoroughly and couldn't find any visible cracks or holes. I then installed the new gaskets, as per the factory service manual, and put everything back together. I started it up and ran it till I was sure I burnt away all the stuff that collected inside. I left is sit for a day and started it up, same problem .

I guess my diagnostic skills need some work, but this is how we learn. Any advice would be great. Thanks in advance!

[ericem]

Maybe it is just the CAT drying up? If it is not loosing any fluid, and there is no overheating I guess leave it? Do a full tune up and that should be fine for a while.

[JabberWalkie]

No there is way too much smoke for it to be a bit of water stuck in the CAT that and it is having quite a lot of trouble starting.

I also preformed another test to help narrow it down:

I detached the exhaust manifold, cranked it over, and checked which cylinder the smoke is coming from. Apparently there is smoke coming from all cylinders! So, either both new gaskets I installed have failed, or I have cracks in both sides?

On a possibly related note, there is coolant running through my throttle body. Does anyone know if a leak there could cause this problem?

Thanks.

[strawman]

Did you recently replace the oxygen sensor with a universal, cut-n-splice unit? I mis-spliced two wires a while back when shoehorning a Suby EJ22 into a Vanagon, and the result was a lot of black smoke but no CEL. Pulled my hair out checking out EVERYTHING until in desperation I unplugged the O2 sensor plug, and the smoke quit. Correctly spliced the wires (the two white wires, if memory serves) and it ran like a champ.

[ericem]

That sucks. Are you loosing a noticeable amount of coolant? There is coolant lines going through the IAC and the throttle body. Maybe the IAC is leaking. I doubt BOTH heads would have cracked.

[JabberWalkie]

Did you recently replace the oxygen sensor with a universal, cut-n-splice unit?

No, the oxygen sensor is the one that has always been in there. Besides, I'm fairly sure this is a coolant leak problem. There are bubbles in the coolant when the car is running, lots of white smoke for about 15 min, engine is very hard to start. Eventually the smoke goes away. This part has me puzzled, if the heads were cracked the smoke shouldn't just disappear like that.

I'm thinking I should get one of those kits that tests for combustion gasses in the coolant. Do you guys think that test would be worthwhile?

Maybe the IAC is leaking.

Yeah, I think this might be the problem, but could a little leak really make it hard to start?

[ericem]

i mean it could be leaking coolant not sure exactly how it is designed but i do know there is a special spring which is sensitive to coolant temperature in order to affect the iac operation.i suggest you pull the iac and possibly replace it. Your car being non turbo it should be pretty easy to access.