Foul plugs and oil leak I cant trace

[kikkegek]

guys,

I had the heads replaced couple months ago...car ran superweet for some week....dirty nr2 sparkplug stayed clean....so I was happy.

last few days started running rough...so tonight I pulled the plugs, finding this.

any ideas? I have no clue where this oil is coming from and how external oil can clog the plug so much?

nr 1








nr3









the glossy black makes it a pain in the ass to see where it is leaking. The shop decided on that color...never again glossy black on my engine parts...

any ideas guys?

[1981Sturgis]

I had this happen on my 87 TBI. It was a loose intake manifold. Sucked the oil from the inside.

[1981Sturgis]

Originally Posted by 1981Sturgis

I had this happen on my 87 TBI. It was a loose intake manifold. Sucked the oil from the inside.

My plugs looked EXACTLY like that. The Chevy dealer didn't retorque the intake after they put a new shortblock in it under warranty.

Since you say you replaced the heads I'd check that. Put a wrench on it and see if it will tighten up any. Mine tightend up 1/2 turn.

[kikkegek]

thats what I am hoping, something simpel.

I read something about failing PCV? how can one check that?

[andrewmp6]

Take the pcv off and shake it if it rattles its fine if it don't make a sound its clogged up and needs replacing.

[kikkegek]

Originally Posted by andrewmp6

Take the pcv off and shake it if it rattles its fine if it don't make a sound its clogged up and needs replacing.

thanks will try that later today and report back....man I hope this is something simple, because we just had a 160 euro repair in this engine...dont want another big bill

[Corts60]

There is no fouling on the tip, which is a good sign. Whatever your leak is, it is external and will be cheaper than repairing anything internal. As stated above, check your PCV to make sure it is working properly. If it is fine, I would pull that valve cover and look to see if that gasket has failed.

[kikkegek]

Originally Posted by Corts60

There is no fouling on the tip, which is a good sign. Whatever your leak is, it is external and will be cheaper than repairing anything internal. As stated above, check your PCV to make sure it is working properly. If it is fine, I would pull that valve cover and look to see if that gasket has failed.

hi Corts60: what do you mean by there is no fouling on the tip? isnt the thing covered in it? can you explain please?

but how would then the fouling inside the cilinder take place, if the oil leakage is external? hope you can help me on this?

[kikkegek]

checked the PCV tonight and it works fine. puled it out, rattles when shaken and when the engine runs it sucks pretty good...so no problem there.

I did find oil in it, should it just suck vapor? and not oil?

also took out the plug again and found a small trail of oil laying in the thread in the head. plug looks like this.pretty strange that it has a black spot on just one side?

[Firebirdjones]

If the heads were rebuilt properly (meaning valve guide clearance set correctly, no guld up valve guides) and good positive seals were used (not cheap 0-rings or umbrellas) Then I would lean towards oil consumption either through a leaking intake manifold sucking oil from the valley, or the PCV.

Since you mentioned your PCV was wet with oil inside that's the first thing I'd change. Either make sure the baffle in the valve cover is there and working, or install an oil catch can before it enters the carb, or remove the PCV all together and use a breather.
Oil through the PCV is coating the entire inside of the intake, all your intake valves and will foul plugs if it's bad enough.

[kikkegek]

Originally Posted by Firebirdjones

If the heads were rebuilt properly (meaning valve guide clearance set correctly, no guld up valve guides) and good positive seals were used (not cheap 0-rings or umbrellas) Then I would lean towards oil consumption either through a leaking intake manifold sucking oil from the valley, or the PCV.

Since you mentioned your PCV was wet with oil inside that's the first thing I'd change. Either make sure the baffle in the valve cover is there and working, or install an oil catch can before it enters the carb, or remove the PCV all together and use a breather.
Oil through the PCV is coating the entire inside of the intake, all your intake valves and will foul plugs if it's bad enough.

thanks, but that stil doesnt explain the oil on my threads and under the car?

[Firebirdjones]

Originally Posted by kikkegek

thanks, but that stil doesnt explain the oil on my threads and under the car?

That's just an oil leak somewhere. Could be that if the intake wasn't sealed properly and is sucking oil through the valley (fouling the plugs) then it's quite possible it could be leaking out the back too. Hard to say. But the plug fouling should be easy to narrow down and that (to me) is a bigger issue at the moment.

[1981Sturgis]

Originally Posted by Firebirdjones

If the heads were rebuilt properly (meaning valve guide clearance set correctly, no guld up valve guides) and good positive seals were used (not cheap 0-rings or umbrellas) Then I would lean towards oil consumption either through a leaking intake manifold sucking oil from the valley, or the PCV.

Since you mentioned your PCV was wet with oil inside that's the first thing I'd change. Either make sure the baffle in the valve cover is there and working, or install an oil catch can before it enters the carb, or remove the PCV all together and use a breather.
Oil through the PCV is coating the entire inside of the intake, all your intake valves and will foul plugs if it's bad enough.

...

[kikkegek]

did some testdriving just now:

- serious downshifting and easy downshifting: no blue smook
- started the car after it had sat for a couple of hours, no white or blue smoke
- no blue smoke during easy and hard acceleration

made a picture of the nr7 cilinder (nr3 in my previous posts, the worst of the two) and what shows is that its only black on the top left (or top right looking at the head of the engine)...bottom is clean and white:




I cleaned the engine on the bottom with brake cleaner and after a little driving there is no oil I can find on the outside.

I did indeed find oil all over the thread of the plug again when I took it out, so took some pics of the plug-hole (is that what you call it?):

With the spark in it, it look dry from the outside:




something I have noticed the last few days is that when I turn off the engine, I hear a dark hum come from under the hood. Jumped out of the car, popped the hood and tried to find it...but it was already allmost gone and couldnt locate it...WTF? it sounds like something has build up pressure and is now releasing it when I turn of the engine...

[Firebirdjones]

Originally Posted by kikkegek

something I have noticed the last few days is that when I turn off the engine, I hear a dark hum come from under the hood. Jumped out of the car, popped the hood and tried to find it...but it was already allmost gone and couldnt locate it...WTF? it sounds like something has build up pressure and is now releasing it when I turn of the engine...

This sounds like no crank case ventilation to me, which will also cause oil leaks. I've had the same thing before. After shutting engine off you hear a light hum or even a whistle. After about 5-10 seconds it stops.

Turned out (for me) there wasn't enough crank case ventilation for the engine.

[kikkegek]

Originally Posted by Firebirdjones

This sounds like no crank case ventilation to me, which will also cause oil leaks. I've had the same thing before. After shutting engine off you hear a light hum or even a whistle. After about 5-10 seconds it stops.

Turned out (for me) there wasn't enough crank case ventilation for the engine.

I did take the PCV out, shook it, it rattles...turned on the engine, felt if it sucked air (vacuum) and it suck my finger very firmly against the PCV...and when it does, I hear a click...dont know what that means.

can I check crank case ventilation by taking of the filter on the other other cover and feel if it sucks air in? or is there another procedure?

[kikkegek]

ok, just started the engine and felt at the other side and I can feel it sucking in air. not as hard as on the PCV valve side, but it suck air in...so there is crank case ventilation.

[Firebirdjones]

If the PCV is working, and you have a breather on the other side to allow air into the crankcase, that should be sufficient crank case ventilation for most any stock or mild engine.

[kikkegek]

Originally Posted by Firebirdjones

If the PCV is working, and you have a breather on the other side to allow air into the crankcase, that should be sufficient crank case ventilation for most any stock or mild engine.

any other ideas what can cause the oil on the threads and the hum when I turn of the engine?

[Firebirdjones]

Without actually being there,,,not really. Just best guesses.

[kikkegek]

Originally Posted by Firebirdjones

Without actually being there,,,not really. Just best guesses.

guess please? any help or tips are welcome

[kikkegek]

looked at the engine yesterday and pulled the plugs after a night of letting it sit.

nr1 cilinder
bottom

topview




driverside front corner near nr1 cilinder



nr5 cilinder
bottom

topview








how can it leak oil at the gasket, when there isnt any oil near?



something I did now notice is that both foul plugs have oil leaks on the outside of the heads...

[grs]

Clean the oil off the engine then start it up and see of you can locate the leak.

[kikkegek]

Originally Posted by grs

Clean the oil off the engine then start it up and see of you can locate the leak.

tried that. thanks, but it leaks to slow to find it like that

[wyattglock]

I dont want to sound like I am picking anyone's work apart, but are there washers under the head bolts? I know that a washer helps spread the torque load evenly and it also helps in the proper pre-load on the bolt. I have seen at the factory I work at, where during assembly if someone leaves a washer out it can affect the flatness desired on the part. This applies to everything from bearing caps to cylinder heads. Just curious about your situation and if the heads arent properly seated due to this.