GM 3800 Series II Oil in Engine

[Steven Cummings]

Hello,

I have been removing my transmission to get to the rear oil seal (leaking :angry: ). I looked through the intake manifold to admire a successful job from when I replaced my intake gaskets which had been leaking coolant/oil previously. To my chagrin I noticed oil sitting on the upper manifold :ohmy: . The good news is that I am not seeing coolant (I have to take the air intake off first to be sure, but it looks only like oil to me). The intake and valve cover gaskets all appear fine on the outside.

I did a cold compression test (don’t hate! the transmission was half-way out) and the numbers all were good (first stroke was between 85-95 PSI and by the third stroke all shown between 145-155 PSI). There does appear to be oil on only ONE side of EVERY sparkplug (I am assuming that this may be oil carried in from the oil sitting on the upper manifold). The PCV is new less than 10K miles. While I can replace this, the amount of oil appears to be above and beyond the PCV system. What else should I look into for sources of oil into the engine? Is a leak down test necessary considering it’s doing well on the compression test, or am I misunderstanding previous videos/guides.

Best, Steven

Topic

[Kevin Criswell]

Can you post a pic of the oil? Some oil in a 3800 Series II engine intake is normal, due to the crankcase ventilation system some oil will get pulled into the intake naturally, but it should not be much.

[Steven Cummings]

Here is a crude picture; I didn’t get your message until this morning and didn’t take the manifold off since I was late for work. Here are two pictures showing both sides of the upper manifold with one clearly showing quite the puddle of oil.

I did not get a picture, but after removing the exhaust crossover pipe last night, it looks like I may have a small oil leak out of the rear head-gasket. Could the excess oil in the engine be related or no considering I saw no ill compression?

Attachments:

• Intakemanifold-front.jpg
• Intakemanifold-rear.jpg

[Steven Cummings]

Update: Finally had a few hours to begin removing the wires/fuel rail/intake. I feel this is too much oil on the manifold and am suspecting a leak from somewhere. I am going to replace the intake manifold gaskets and PCV assembly. What else should I be looking at?

Attachments:

• UpperManifold-Nointake.jpg

[Kevin Criswell]

I agree that is a bit too much oil

what’s the year of the vehicle?

[Kevin Criswell]

Looks like a issue in the PCV system, have you tried swapping out the valve?

[Steven Cummings]

Hi,

Just to follow up on this job. I completed it about a week ago and have put on roughly 400 miles since then.

The following leaks/issues were seen during top-end deconstruction:
1) Both head gaskets (just slight on the front, substantial on the rear)
2) Solid (not soft/squishy) valve seals on cylinder 4
3) HUGE/thick Carbon build ups on the rear cylinders (lesser on the front)
4) Bad rear-main seal (taking off the cover resulted in lots of little pieces
5) Pieces of almost saran-wrap like material on the lifter guides for cylinder 3/5 (I suspect this material is what made the engine smell bad once it was hot as it had the same smell when cold…I can’t help but smell anything anomalous)

The good news was that a straightedge shown no detectable warping in the heads and the cylinder walls were pristine and no scratches/marks

The PCV system all had nice looking O-rings still and the PCV valve wasn’t that old (maybe 10K). The PCV valve could have been defective accounting for the excess oil pooling on the lower manifold.

The following jobs were completed (some not related, but problems found in the meantime
1) Cleaned and polished carbon buildup for heads and cylinders
2) reseated valve-stems
3) New head, exhaust valve cover gaskets (re-used my metal intake gaskets as they were in excellent condition and no oil leaks were seen here)
4) aluminum coolant elbows added
5) new rear main gasket and oil seal
6) new flexplate (old one was warped…possibly from oil leaking onto the hot plate?)
7) new driveaxle seal and updated car to DexVI (It now shifts like a knife through butter!)
9) New hub assembly (it fell apart on me! That explains the ABS light coming on now)
10) New intake manifold and PCV valves/plenums (likely not necessary, but the stories of failing intakes have scared me even though I believe this was fixed for the 2004 model year)

So far all has been good and the engine feels more solid again.

I now hear new noises/concerns that I vaguely recall hearing before, but couldn’t distinguish over the squealing of the warped flexplate. I will post these in another thread though.

I guess I will follow up with this question: Could bad valve stem seals/head gaskets lead to oil on the upper manifold? I wouldn’t think so based on the way the air flows into the cylinders, but am not sure.

[Author]

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