2003 Yukon losing ~3 quarts oil over 3k miles

[DonnieBrasco]

Yukon has about 225K miles on it. Lately I've been noticing a "check oil level" message on the dash that usually pops up near the end of an oil cycle (around 2800-3000 miles) but when I check the dip stick everything seems fine. Moreover, I never notice a pool of oil under my car in the driveway or anything.

I know I am losing a tiny bit from the oil plug because it needs replacing and I just haven't gotten to it. When I changed my oil last week I finally took note of exactly how much oil I am draining out. I only drained out about 2 quarts of oil. So I'm losing/burning/vanishing about 3 quarts of oil over the course of an oil cycle. My exhaust isn't blowing black smoke. I never smell oil burning.

When I was underneath it changing the oil, I did notice a lot of areas around the engine block, particularly around joints/gaskets, with a lot of oily gunk and residue. I'm not exactly sure what areas I noticed it but it looked like all around the intake manifold or exhaust and all around the underneath areas of the block. However, I didn't notice much (or any) around the oil pan (thus indicating an oil pan gasket issue).

What are my first steps to tracking this down? What seals/gaskets do I need to check and is this a DIY issue? I've done TPS replacements, water pumps, brakes, oil changes, etc. But if it involves pulling the whole damn engine out or worse, I think that's over my abilities. Thanks.

 

[TheAutumnWind]

Going to have to narrow it down.

If its mostly towards the rear of the block and the front of the trans its likely a rear main seal which is a big job. Requires trans removal and costs a decent amount of labor.

 

[DonnieBrasco]

Going to have to narrow it down.

If its mostly towards the rear of the block and the front of the trans its likely a rear main seal which is a big job. Requires trans removal and costs a decent amount of labor.

Yeah...I was worried about that. I'll try and get back under it this weekend and hopefully get some good pictures to try and narrow it down.

 

[95escahoe]

Get under there clean up the oily spots, then keep an eye on it and see where it leaks from and go from there


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[DonnieBrasco]

Get under there clean up the oily spots, then keep an eye on it and see where it leaks from and go from there


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You know, I feel like a dumbass because I hadn't even thought of doing that. Anything I should (or should not) be using with shop rags to make it easier to remove the gunk?

 

[Z28TWITCH]

Before you go panicking over a rear main seal job, check you oil pressure sender at the back of the intake manifold...lots of guys have gotten the trans out only to realize that their weekend was wasted because of a $25 part...I replaced 2 on my truck...and about 40 on other tahoes/yukons. the way I stopped it was I used the blue devil brand teflon tape because the stuff they use to "seal" the thread from factory is crap....just my .02
A lot of 5.3s do actually need a rear main seal though, definitely want to be 100% before you tackle that job.

 

[DonnieBrasco]

Before you go panicking over a rear main seal job, check you oil pressure sender at the back of the intake manifold...lots of guys have gotten the trans out only to realize that their weekend was wasted because of a $25 part...I replaced 2 on my truck...and about 40 on other tahoes/yukons. the way I stopped it was I used the blue devil brand teflon tape because the stuff they use to "seal" the thread from factory is crap....just my .02
A lot of 5.3s do actually need a rear main seal though, definitely want to be 100% before you tackle that job.

That's an excellent point. Not to mention, my oil pressure gauge has been a little wonky lately. Nothing crazy, but it fluctuates more than usual. I might go ahead and change that guy. Is it easy to access, i.e., how much shit do I need to pull out to get to it? Thanks for the heads up.

 

[TheAutumnWind]

Before you go panicking over a rear main seal job, check you oil pressure sender at the back of the intake manifold...lots of guys have gotten the trans out only to realize that their weekend was wasted because of a $25 part...I replaced 2 on my truck...and about 40 on other tahoes/yukons. the way I stopped it was I used the blue devil brand teflon tape because the stuff they use to "seal" the thread from factory is crap....just my .02
A lot of 5.3s do actually need a rear main seal though, definitely want to be 100% before you tackle that job.

That's good info. If i ever get my nali back from the body shop im going to look in to that, since i've got a leak in that area.

 

[95escahoe]

You know, I feel like a dumbass because I hadn't even thought of doing that. Anything I should (or should not) be using with shop rags to make it easier to remove the gunk?

I'd used brake clean on a rag don't go spraying it, or use degreaser etc. whatever does a good job cleaning it and doesn't harm anything, I tend to stay away from the red shop rags, leaves nothing but red fibers all over white rags or old shirts work better imo


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[95escahoe]

That's an excellent point. Not to mention, my oil pressure gauge has been a little wonky lately. Nothing crazy, but it fluctuates more than usual. I might go ahead and change that guy. Is it easy to access, i.e., how much shit do I need to pull out to get to it? Thanks for the heads up.

YouTube it there are a few vids on how to get to it, it's on the back of the block, can reach down and get to it maybe use a mirror so u see where your going, gonna need a deep well socket to remove it


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