Oil leak. Discovered hole in transmission housing?

[dammad]

I noticed some oil drips from my 2008 Yukon Denali over the weekend. Crawling underneath I noticed oil coming from the seal between what looks like the engine and transmission. Then I looked again and noticed what looks like a small chunk of the housing missing. I can shine light in this hole so it is definitely a hole. See the red circled parts on the attached pics.

Is it serious?





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[Doubeleive]

I noticed some oil drips from my 2008 Yukon Denali over the weekend. Crawling underneath I noticed oil coming from the seal between what looks like the engine and transmission. Then I looked again and noticed what looks like a small chunk of the housing missing. I can shine light in this hole so it is definitely a hole. See the red circled parts on the attached pics.

Is it serious?

View attachment 245227
View attachment 245228


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that little chunk out of the bellhousing isn't hurting anything, take that little metal round puck cover (inspection plate) off just to the side of that chunk and look in there with a flashlight, it might be the rear seal leaking or it could be coming from above from either the valve covers or oil pressure sensor

 

[PG01]

Those are cast into block/transmission and not a hole.... there is no sealing gasket in there.
That said there is whats called a rear main seal that is on the back of the engine block that is leaking and dripping down the back through those ‘holes’.
Is it serious... yes and no....its common issue as the engine gets older and rolls more miles and the transmission needs to be removed to fix it and there are specialized tools to install (although not really needed but recommend) How much oil are you losing, have you checked the dipstick? Are there drips on the floor? Etc. Once it starts it will just get worse over time/miles. Do you have to get it done tomorrow, no, you can shop around to diff mechanic/dealers to get a few quotes but I personally would stay away from the dealership. Cost will vary in different areas of the country and from dealer to private mechanic and if you have 2wd vs 4wd(awd) etc. You are going to spend a MINIMUM of $600 and that’s because it is labor intensive yet the seal is relatively cheap...hope this helps

 

[donjetman]

Probably your rear main seal. I replaced mine 17 mths ago. Here is a thread w/pics I did back then.
https://www.tahoeyukonforum.com/threads/rear-main-seal-job-pan-etc-07-yukon-denali-6-2.108334/

 

[dammad]

Many thanks for all the feedback. I’ve been looking at other sources of the oil leak and agree it is probably the rear main seal. A minor drip at this point but will keep an eye on it.


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[Rocket Man]

Many thanks for all the feedback. I’ve been looking at other sources of the oil leak and agree it is probably the rear main seal. A minor drip at this point but will keep an eye on it.


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If it is indeed the rear main be sure to keep an eye on oil loss since it will get worse over time.