Oil Leak

[zerovandez]

Ive only started to drive my 02 TB LTZ frequently this year. She now has 135k on the odometer. I noticed engine oil disappering rather quickly. Ive done 2 oil changes and used different brands all 5w30. Recently, i put 3k miles on her and the oil level dropped down to half on the dipstick.

So i crawled under and removed the skid plate. It was really wet where the differential met the oil pan. There doesnt seem to be any visible leaks from the differentials seal, drain, and fill plugs. I dont notice any fluid running from the head to the block, or the block to the oil pan. So from the wet area previously mentioned, the drain plug on oil pan seems to be wet as well. The drain plug is not oem but one from Dorman which had a new seal when I replaced it.

Again, not where its leaking engine oil - cant see any evidence from head to block and/or from block to oil pan. Any suggestions out there?

[rScherzer]

Sounds like there could be a few things going on. 1st is what do you call a leak. Dripping on the ground or a film? 2nd there is a seal on the right side of the diff that is recessed into the engine oil pan that you cant physically see unless the diff is pulled out. 3rd is the engine my be using the oil. I did a Search and found a few GM documents that might point you in the right direction also. On rare occasions, an engine oil leak may be noted just below the PCV port between the number 3 and number 4 intake manifold runners. This may be due to oil that settles in the bottom of the intake manifold due to an internal porosity concern with the cylinder head that can cause oil to enter the PCV system. PIP3590 On rare occasions, an engine oil leak may be noted just below the PCV port between the number 3 and number 4 intake manifold runners. This may be due to oil that settles in the bottom of the intake manifold due to an internal porosity concern with the cylinder head that can cause oil to enter the PCV system
02-06-01-033
Some customers may comment about oil spots on the driveway or an apparent oil leak. Upon investigation, the technician may find that the leak is coming from the area of the oil pressure switch (The switch is on the left side of the engine block I believe.

There are a few places to look. Mine uses a little bit of oil but not more than a quart in 3k. Also how its operated like high speed for long time (Interstate speed) Hard acceleration and high RPM. The things gotta stay lubed lol. Hope that helps. If you have access to engine oil dye and a black light it makes it real easy to find exactly where its coming from.

[zerovandez]

Hey thanks for the info!

I will check the intake runners this weekend. The leak is more than a film. Its actually dripping on and somewhat pooling on the factory skid cover. Most notable drops are coming from the mating area of oil pan and front differential. I cant tell if its engine oil leaking from the pan area and collecting in this mating section, or if its diff fluid from the inner seal. I will clean it up and drop dye in the engine oil.

My worst fear is that the inner diff seal is leaking as well. Im reading that even the brightest of wrenchers and ortb'ers dread having to drop that diff. Sucks!

Edit: i replaced the oil pressure switch not too long ago and yes, at that time it was leaking from this area but i dont notice anything from there since I replaced the part.

[rScherzer]

I don't mind pulling the front diff, then again I work at a GM shop so its expected of me to know how. Plus having a lift makes life so much easier.

[zerovandez]

Well lucky you lol. Any tips, suggestions, or links that you recommend to tackle this task should I actually need to remove this front differential?

[rScherzer]

if ya look around this forum there is a thread on how to remove the diff from the top. I believe its like remove the alternator, ecm and a few other things on the left side of the engine. I personally Undo the fan to water pump. ( I leave the fan in) I unbolt the engine mounts and lift the engine. I then roll the diff assembly backwards and it normally falls out.