Strange oil leak

[Josephbnowak]

Hello everyone, long time browser, first time user. I haven't found anyone with this leak before so I'm posting it here.

Today I've been temporarily banned from my indoor storage facility as the manager informed me that my oil leak has now progressed to "dripping as I'm leaving" and it's dropping everywhere. Before this, I laid a piece of cardboard down under the engine area because I have a minor real main leak that I intend to get fixed once I get the money, but as far as I know it's never leaked as I'm driving.

Out of sheer curiosity, I noticed this new leak. It seems to be leaking across the support bar near the transfer case. I can't see anything above it. Does anyone know what could possibly cause this leak to go this far? It's all new to me. Thank you in advance.

 

[strutaeng]

The seal between the transmission and the transfer case?

 

[Fless]

Year, make, and model? What 4x4 system (2 speed, AWD)?

Are you certain that it's engine oil?

 

[frank1]

Check the transfer case/ trans adaptor. Mine had stress cracks and leaking from the top, then down the side.

 

[justirv]

Check the transfer case/ trans adaptor. Mine had stress cracks and leaking from the top, then down the side.

The transfer case can also leak due to pump/case wear causing a pinhole leak. There is a case-saver available if needed after a spot-weld repair, or case replacement.

 

[Mudsport96]

As much oil as is burnt onto the y pipe and on the transmission pan, I'm going to wager that engine oil is collecting in the cross member and no coming out when the truck moves

 

[wjburken]

The leak is upstream of the y-pipe as evidenced by the coating on the leading edge of that pipe. I would look at everything in front of that. Oil cooler lines, oil pan gasket, etc.

 

[89Suburban]

Man I don't miss that sh*t

 

[Doubeleive]

Hello everyone, long time browser, first time user. I haven't found anyone with this leak before so I'm posting it here.

Today I've been temporarily banned from my indoor storage facility as the manager informed me that my oil leak has now progressed to "dripping as I'm leaving" and it's dropping everywhere. Before this, I laid a piece of cardboard down under the engine area because I have a minor real main leak that I intend to get fixed once I get the money, but as far as I know it's never leaked as I'm driving.

Out of sheer curiosity, I noticed this new leak. It seems to be leaking across the support bar near the transfer case. I can't see anything above it. Does anyone know what could possibly cause this leak to go this far? It's all new to me. Thank you in advance.

your primary suspects are
1. valve cover gaskets
2. oil cooler line adapter plate (above oil filter)
3. oil pan gasket
4. rear main
5.. oil pressure sensor
I would go buy a couple large spray bottles of degreaser such as purple power or anything industrial strength, then go to a self car wash with the high pressure sprayers, park in the stall and pop the hood and start spraying the degreaser all over the engine and up under the engine as much as possible. then pressure wash it, you can do this safely without harm just do not spray directly into the alternator or visible electrical connectors. you will want to concentrate on getting any visible oil cleaned off everywhere you can. Then right after drive it up on some stands or use a jack and get under there with some rags and start cleaning off anything else you can see that the pressure washing did not get.
then drive it for 1 day and again get under it with a flashlight and starting looking around for FRESH oil.
my bet is most if not all the things I mentioned above are leaking, it's just how it goes.

 

[Josephbnowak]

your primary suspects are
1. valve cover gaskets
2. oil cooler line adapter plate (above oil filter)
3. oil pan gasket
4. rear main
5.. oil pressure sensor
I would go buy a couple large spray bottles of degreaser such as purple power or anything industrial strength, then go to a self car wash with the high pressure sprayers, park in the stall and pop the hood and start spraying the degreaser all over the engine and up under the engine as much as possible. then pressure wash it, you can do this safely without harm just do not spray directly into the alternator or visible electrical connectors. you will want to concentrate on getting any visible oil cleaned off everywhere you can. Then right after drive it up on some stands or use a jack and get under there with some rags and start cleaning off anything else you can see that the pressure washing did not get.
then drive it for 1 day and again get under it with a flashlight and starting looking around for FRESH oil.
my bet is most if not all the things I mentioned above are leaking, it's just how it goes.

Thank you so much for your detailed response. The oil pressure sensor and valve cover gaskets were all replaced last year. We replaced I think it was called an oil cooler gasket as well... tiny little diamond shaped thing. I wonder if it's simply possible that my rear main leak has gotten worse. Either way, I'll try that and get the truck up on a lift soon and report my findings.

 

[Doubeleive]

Thank you so much for your detailed response. The oil pressure sensor and valve cover gaskets were all replaced last year. We replaced I think it was called an oil cooler gasket as well... tiny little diamond shaped thing. I wonder if it's simply possible that my rear main leak has gotten worse. Either way, I'll try that and get the truck up on a lift soon and report my findings.

the bottom line is your going to have to clean it up real good first then look for fresh oil after driving it a bit.
for the rear main there is a inspection plate on the transmission bell housing, you can pop that plate off and look inside there with a flashlight and small tilting mirror that you can get at any autoparts store.
this video goes over some things to look for I would say the front seal they show leaking in the video is less common but also possible

 

[89Suburban]

valley cover

 

[Doubeleive]

valley cover

Meh, not likely

 

[mjpeterson]

Has the water pump been replaced at anytime? my 2005 started to slightly leak at the timing seal about 6 months after the wtr pmp replacement, probably due to over tightening the wtr pmp bolts?

 

[KC 2013 Tahoe]

Rear main seal leaks don't typically remain static, nor improve... would guess that's your culprit given the other repairs you've had done.

 

[Josephbnowak]

I appreciate everyone's replies. My mechanic buddy who really knows his stuff and these trucks is gonna come over at the end of the week (presumably) and take a look. Definitely still leaning towards rear main seal. It hasn't leaked as much oil towards the back these days which is just odd. But still the same drops directly under the engine as it always has.

 

[Josephbnowak]

Has the water pump been replaced at anytime? my 2005 started to slightly leak at the timing seal about 6 months after the wtr pmp replacement, probably due to over tightening the wtr pmp bolts?

Nope not in the several years I've owned this truck.

 

[Josephbnowak]

Year, make, and model? What 4x4 system (2 speed, AWD)?

Are you certain that it's engine oil?

2001 Yukon Denali AWD. Yes I am pretty certain. Could maybe be gear oil but I doubt it. But I also can't really tell from ground level.