07 Yukon Denali - Passenger Side Top/Rear Oil Leak

[89Suburban]

OP nice work and investigation, determination and repairing. I am very critical of the valley cover leak blowing oil on top of the coils, that makes no sense to me. I have been here before and mine was worse than yours, but I did not have that issue. hopefully I m wrong in your case.

As I was reading through these posts I started to think the same thing as @Foggy , possible trans tube leak at the dipstick seal. Mine is very worn and hardened and loose. I made a thin aluminum shim to stick under the lever lock to snug it up a little.

I was also told to use GM seals on the valve covers. I replaced mine with the blue fel pro's and they only lasted a few years and started leaking again on the driver's side. I am being told my a local reputable mechanic that is a known issue om the fel pros for these motors.

It's also my experience every time I track down an oil leak and fix it it starts leaking somewhere else. But my motor is near 350K and has major blowby so it is to be expected.

I am really enjoying watching your posts and pics, thanks for sharing and wish you well on your task.

 

[zissou]

OP nice work and investigation, determination and repairing. I am very critical of the valley cover leak blowing oil on top of the coils, that makes no sense to me. I have been here before and mine was worse than yours, but I did not have that issue. hopefully I m wrong in your case.

As I was reading through these posts I started to think the same thing as @Foggy , possible trans tube leak at the dipstick seal. Mine is very worn and hardened and loose. I made a thin aluminum shim to stick under the lever lock to snug it up a little.

I was also told to use GM seals on the valve covers. I replaced mine with the blue fel pro's and they only lasted a few years and started leaking again on the driver's side. I am being told my a local reputable mechanic that is a known issue om the fel pros for these motors.

It's also my experience every time I track down an oil leak and fix it it starts leaking somewhere else. But my motor is near 350K and has major blowby so it is to be expected.

I am really enjoying watching your posts and pics, thanks for sharing and wish you well on your task.

About 300 miles logged now and it has been trouble free since the valley cover gasket. No more oil smell in the cabin, no more smoking, no oil on the coils. I think the valley gasket was so bad that lots of oil was getting out and it was just spraying in the wind all over on the interstate (80mph speed limits out here). I also picked up some oil pressure with the new gasket.

I ran into a problem with the VVT magnet and had to put the old one back in. The harness changed slightly so I had to order the updated harness to fit the new 12653140 magnet. The original harness does not click and lock on the new magnet. The replacement harness is 12663001 (I think... we'll see).

Also have a ton of front suspension showing up this weekend too (upper & lower control arms, inner and outer tie rods, end links, sway bar bushings, an axle).

 

[89Suburban]

About 300 miles logged now and it has been trouble free since the valley cover gasket. No more oil smell in the cabin, no more smoking, no oil on the coils. I think the valley gasket was so bad that lots of oil was getting out and it was just spraying in the wind all over on the interstate (80mph speed limits out here). I also picked up some oil pressure with the new gasket.

I ran into a problem with the VVT magnet and had to put the old one back in. The harness changed slightly so I had to order the updated harness to fit the new 12653140 magnet. The original harness does not click and lock on the new magnet. The replacement harness is 12663001 (I think... we'll see).

Also have a ton of front suspension showing up this weekend too (upper & lower control arms, inner and outer tie rods, end links, sway bar bushings, an axle).

That's good to hear. Wow man lots of front end work to come, nice!!!! Try to get us pics if you can.

 

[zissou]

Front suspension is all refreshed. New upper and lower control arms, inner and out tie rods, new axles, sway bar end links, and sway bar bushings and had it aligned. Rides a million times better now.

 

[zissou]

Transmission cooler lines have now been replaced too. These were more of a PITA than I anticipated but got it done this afternoon. I had a leak at both the mating gasket to the side of the transmission as well as one of the crimps.

However my oil leak saga is beginning to look pretty clear as it nears the end. I've eliminated so many leaks but one still remains... There is definitely some oil flung around inside the bell housing and I continue to get 2-3 small drops on the garage floor each night. Looks like a rear main seal and rear cover gasket are in my future. I've gone 90% the way replacing everything else, I'll just need to bite the bullet and do the rear seal. Might take a week or 2 off from working on this truck, but I'll follow back up.

 

[donjetman]

Looks like a rear main seal and rear cover gasket are in my future. I've gone 90% the way replacing everything else, I'll just need to bite the bullet and do the rear seal. Might take a week or 2 off from working on this truck, but I'll follow back up.

I did the rear main engine seal on our 07 6.2L awd Denali 4 yrs and 45k miles ago. All is good still. It has 185k miles now. Here's the link: https://www.tahoeyukonforum.com/threads/rear-main-seal-job-pan-etc-07-yukon-denali-6-2.108334/

 

[zissou]

I did the rear main engine seal on our 07 6.2L awd Denali 4 yrs and 45k miles ago. All is good still. It has 185k miles now. Here's the link: https://www.tahoeyukonforum.com/threads/rear-main-seal-job-pan-etc-07-yukon-denali-6-2.108334/

Good to know. Thankfully I have hoists as well, so like you it seems less daunting. It's just nuts and bolts after all. Part of me thinks I'm a little crazy doing all this on a 230k mile truck that I've only driven about 800 miles~ since purchasing, but it's one of those cars that you just know is a good one and worth saving.

 

[89Suburban]

I did the rear main engine seal on our 07 6.2L awd Denali 4 yrs and 45k miles ago. All is good still. It has 185k miles now. Here's the link: https://www.tahoeyukonforum.com/threads/rear-main-seal-job-pan-etc-07-yukon-denali-6-2.108334/

Awesome stuff in there thanks.

 

[zissou]

A lot going on this weekend, VVT delete and a cam going in, plus I decided to bite the bullet and drop the oil pan again to put in a Melling M295 oil pump while I'm at it.

Doing some prep work tonight, pulled the front diff off, 2nd time around it came off in about 30-45 minutes.

Previous owner messed up the drain plug on the pan and sick of dealing with it. Either going to rethread it or just order in a new pan... we'll see.

Had some snow today and should have washed the truck before I started, but oh well.

 

[Geotrash]

A lot going on this weekend, VVT delete and a cam going in, plus I decided to bite the bullet and drop the oil pan again to put in a Melling M295 oil pump while I'm at it.

Doing some prep work tonight, pulled the front diff off, 2nd time around it came off in about 30-45 minutes.

Previous owner messed up the drain plug on the pan and sick of dealing with it. Either going to rethread it or just order in a new pan... we'll see.

Had some snow today and should have washed the truck before I started, but oh well.

What's the deal with the transmission pan? Looks like it was high-centered on a rock or somethin'.