Compression loss?

[19Cutlass94]

Its either the intake/exhaust valve seals that are leaking, or its the rings. But would either one of these cause a loss in compress? Its leaking in all 6 cylinders so if it would cause a loss, I would think it would be somewhat noticable. Because oil is getting past one of the two and leaving oil ash on the plugs, therefore fouling the plugs after a while (more like a shorter time) but with all of that combined, would that cause a compression loss? Or would the easiest thing to do, do a compression test? (which I duno how to do)

[1990lumina]

If either one of the valves are leaking, then yes, you will be having a loss in compression I think....on the compression stroke both valves will be closed before ignition, and if one or both are leaking, then you'll lose compression. I think anyway

[94CutlassXtreme]

Both valves are closed at top dead center compression

[joey b]

did you do the test with engine at operating temperature? To be leaking at all 6 cylinders and just now be noticed is kinda wierd.

[19Cutlass94]

Well I didnt do a compression test. Ive known for a little bit that its either been the seals or the rings that are leaking cause my plugs keep getting fouled with oil. But either the seals or rings are leaking in all 6 cylinders.

[joey b]

to test the rings you need it to be at operating temp and fill the cylinder with a bit of oil. If you get considerably boosted compression by doing this, then it is the rings, which I have been told are definately not infallible on these engines. Do you have blowby?

[GutlessSupreme]

did you do the test with engine at operating temperature?

 

BAD IDEA ALERT!

 

DON'T PULL THE SPARK PLUGS IF THE HEADS ARE AT OPERATING TEMP!

[joey b]

compression tests are not supposed to be done when the engine is cold.

[19902drlumina]

:withstupid: plugs +heat =bad/stripped threds and a bigger headache

[joey b]

http://www.w-body.com/forum/viewtopic.php?t=29640&highlight=compression

[19902drlumina]

well in ase class it needs to be warm to do a compression check. but with our alum heads it would cause damage just taking the plugs out. (my step dads car has that prob now because of a tuneup he stripped all the threds) so if u have to do a cc id do it cold just my.02cents

[mfewtrail]

You can do a "cold" compression test, cold readings will be slightly lower than if you did a hot test.....but that's the way it has to be done with aluminum heads unless you want to risk having your plugs not thread back in them.

 

I really don't think you have oil on your spark plugs, it's likely fuel. Take of picture of them next time you pull them. Do you ever see any oil smoke(blue in color) from your exhaust? EDIT: Also, how much oil do you lose(if any) between oil changes?

[jeremy]

I've always heard compression tests should be done on warm engine, I just don't have the balls to try it

[joey b]

I've pulled plugs on warm engines more than once and haven't had any problem. Make sure that the plugs aren't rusted in there you heat it up.

[19Cutlass94]

You can do a "cold" compression test, cold readings will be slightly lower than if you did a hot test.....but that's the way it has to be done with aluminum heads unless you want to risk having your plugs not thread back in them.

 

I really don't think you have oil on your spark plugs, it's likely fuel. Take of picture of them next time you pull them. Do you ever see any oil smoke(blue in color) from your exhaust? EDIT: Also, how much oil do you lose(if any) between oil changes?

 

I duno how it would be fuel fouling the plugs since its oil ash on them? Next time I have em out Ill take some pictures. I dont see any smoke at all, but means its not a massive oil leak, but I put about a quart in it every 2 weeks or so depending on how much I drive. (Well I have the oil pump o-ring leaking, leaking gaskets and either leaking valve seals or rings)