Oil Leak Near Transmission Pan

[Billydunwoody]

So a while back I posted that I had some oil drops in the driveway and when I looked under the Tahoe it was seeping near the transmission pan. About 3 weeks ago I finally had my mechanic replace the oil cooler gasket as suggested. On Friday, I noticed 2 oil drops back on the driveway so I went under and cleaned the whole underside with engine cleaner and wiped it dry with a paper towel. Today, I went under and 2 days later, (picture taken 2 days after cleaning the underside) it appears to be seeping from the same spot by the transmission pan. I checked everywhere else and it is dry. It is not transmission fluid, it is oil. I am not losing anything on the dipstick however I do not like having a car that leaks, so does anyone have any ideas? Picture attached. 08 Tahoe 5.3L V8, 4WD, 108K miles.
1st picture is where the oil is seeping from (this area was cleaned well 2 days before and the second picture is the oil cooler gasket that was replaced and it is dry).
Thanks!

 

[strutaeng]

It could be the engine rear main seal. Is there any oil on the engine oil pan? If it's rear main seal it tends to leak and run back down to the engine oil pan on the rear.

Can you take a peek through the transmission bellhousing inspection port? Adding a dye with a UV light will help you pinpoint it.

 

[Billydunwoody]

It could be the engine rear main seal. Is there any oil on the engine oil pan? If it's rear main seal it tends to leak and run back down to the engine oil pan on the rear.

Can you take a peek through the transmission bellhousing inspection port? Adding a dye with a UV light will help you pinpoint it.

I checked the pan and there was no active oil / seeping. My mechanic only noted that the oil pan gasket was probably replaced in the past because there was old sludge but nothing active.
Where exactly is the inspection port if you don't mind telling me?
Thanks

 

[Dustin Jackson]

Your oil cooler gasket doesn’t look like it’s leaking but it also doesn’t look like it was changed…

 

[Geotrash]

Your oil cooler gasket doesn’t look like it’s leaking but it also doesn’t look like it was changed…

Good eye. I thought the same thing. If that thing had been changed, those bolts would show signs of having had a socket on there.

To the OP, you don't have an oil cooler on that truck, but you do have a block-off plate in that spot by the oil filter. Super common leak spot. I would change that gasket out and use an OEM or Dorman one (uses the OEM design). The aftermarket ones don't seal well because they require too much clamping force. Torque spec is 108 *inch* pounds. Be careful because those bolts are small and the threads are aluminum.

More Information for GM GENUINE 12611384

 

[Meathead16]

^x3

Looking closely, it looks like the engine side is dry, while the cover plate has that 'moist' look to it. Also, if it was off recenty, the gunk circled with blue would have been disturbed and not line up so perfectly, or at the very least have a slight crack between the cover and engine from being broken apart, but they seem to be one and intact:

 

[donjetman]

^x3

Looking closely, it looks like the engine side is dry, while the cover plate has that 'moist' look to it. Also, if it was off recenty, the gunk circled with blue would have been disturbed and not line up so perfectly, or at the very least have a slight crack between the cover and engine from being broken apart, but they seem to be one and intact:

View attachment 412633

No it hasn't been off.
I replaced the rear main seal 5 yrs ago. Still dry as a bone 60k miles later.
https://www.tahoeyukonforum.com/threads/rear-main-seal-job-pan-etc-07-yukon-denali-6-2.108334/