Help with an Oil Leak Diagnosis

[Keoder]

I've searched this forum, so I apologize if I'm contributing to the bludgeoning of a dead horse but I need the expertise of you all.

I have a 2007 Yukon Denali with 96,000 miles and recently noticed the oil leak that seems to be prevalent with these engines. In order to gauge how much money I need to save, which will drive how quickly its repaired, I was wanting to know where the leak is originating.

From underneath, looking at the rear main seal on the passenger side it starts at the starter bolts on the oil pan and the next oil pan bolt towards the front has a small amount. I removed the inspection plate on the bell housing and didn't feel any oil there. How do I know if it is the crank seal or if it is in fact the rear main seal? Am I going to have to buy the oil dye? If so, how in the world will I be able to see if it's not coming from the top and running down the rear main cover plate? In other words, could the dye lead me wrong?

Appreciate the guidance.

 

[992dr]

From what I've read, the most common problem is the oil cooler block off plate.

The flow of fluids will go towards the back regardless. Its not the quickest process, clean up everything as best as possible from the front of your engine to the back and see if you an find the source.

I'd start there.

 

[ivin74]

Its the rearmain seal, be ready to cough up about a grand. if u do replace the rear main seal go ahead and do the oil pan gasket as well while u are already there thats also a common oil leak spot.

 

[Keoder]

Any way for me to diagnose it's a rear main seal on my own or is this a dealership thing? No way it can be a crank seal, right?

I've replace the oil cooler gasket.

 

[ccapehartusarmyINF.(ret)]

its the rear main seal its always the rear main seal
i had it replaced in my tahoe at about 120k miles and goin thru the maintenance records of this suburban i bought the guy i bopught it from had it replaced about 30k miles ago

 

[t76turbo]

Bad thing is it may be the plate the rear main seal rides in. You would never be able to tell for sure until you pulled the trans.

Another thing to look at is the oil sending unit which is at the very back of motor above the trans. Oil in these areas gets blown around and pulled by gravity and can look like it is coming from one place and really coming from another.

I had a similar leak. Luckily a buddy of mine is a pro and has a lift and we pulled it all and resealed everything. Including front cover and did a water pump, oil pump, oil pan gasket, rear main, that rear cover seal that the main seal sits in, among a number of other things.

 

[992dr]

Bad thing is it may be the plate the rear main seal rides in. You would never be able to tell for sure until you pulled the trans.

Another thing to look at is the oil sending unit which is at the very back of motor above the trans. Oil in these areas gets blown around and pulled by gravity and can look like it is coming from one place and really coming from another.

I had a similar leak. Luckily a buddy of mine is a pro and has a lift and we pulled it all and resealed everything. Including front cover and did a water pump, oil pump, oil pan gasket, rear main, that rear cover seal that the main seal sits in, among a number of other things.

THAT'S what I was thinking of earlier.
Another common leaker.
Like I said and t76 has mentioned the fluids move around.
What may seem like one thing could be another.
Cleaner up and start from there.

 

[jagi0966]

Or just drive it. Is it that big a deal?

 

[Keoder]

Just had a shadetree mechanic fix the leak for me. (I'll caveat by saying it's only been a day since the repair, so I'm driving it in order for me to look again later to verify that there are no leaks.) All along I thought it was the rear main given the discussion on here and even finding some threads that had pictures of my exact same oil drip (just off the inspection plate on the bell housing and the passenger starter bolt on the oil pan). Anyway, in my case, the oil pan gasket was bad. He showed it to me along with the old rear main seal and the old rear cover gasket, both of which were in good shape, but the oil pan gasket had torn on the driver side where the oil coolant lines would run if I had them in my Yukon. I suppose this was running to the opposite side of the engine and then gravity was doing its thing. When I cleaned it off late last year, I saw the problem developing on the passenger starter bolt first, which was why I thought it was the rear main.

All this is to say, if you have a similar occurrence, go ahead and replace the rear main seal, rear cover gasket and the oil pan gasket. The mechanic said it was a pretty tough job that takes a couple of people as he had to drop the transmission and take out the transfer case to get to the oil pan gasket since these vehicles are AWD.

 

[992dr]

Did you happen to remove the inspection plate and look inside?
That is where the oil would have come from if it were a rear main seal leaking. Problem would've been solved and you would've saved yourself a lot of dough. Especially since the oil pan gasket was the culprit.
Regardless, its fixed and now you don't have to worry about it for a very long time.