Help Diagnosing Oil leak

[lspann3525]

Well im back again with another oil leak after a couple of oil pan gasket changes,rear mail seal replacement and valve cover gasket replacement.

Lately ive noticed my 08 tahoe has been drinking oil so I decided to check the oil pan area and I discovered the front area of the oil pan is covered in oil. I doubt its the oil pan gasket. I replaced it maybe 10 months. Im trying to pin point this im thinking maybe timing cover seal or crankshaft seal??? Anything else in this area that can cause this mess. Heres a video.. any suggestions will help.

 

[donjetman]

Well im back again with another oil leak after a couple of oil pan gasket changes,rear mail seal replacement and valve cover gasket replacement.

Lately ive noticed my 08 tahoe has been drinking oil so I decided to check the oil pan area and I discovered the front area of the oil pan is covered in oil. I doubt its the oil pan gasket. I replaced it maybe 10 months. Im trying to pin point this im thinking maybe timing cover seal or crankshaft seal??? Anything else in this area that can cause this mess. Heres a video.. any suggestions will help.

Oil consumption:
Install a catch can and have you or a PO installed the improved driver side valve cover per GM TSB# 10-06-01-008M? https://f01.justanswer.com/ebrock63...il+Consumption,+MIL+ON,+Engine+Runs+Rough.pdf

When you had the pan off, I hope you installed a new oil pump to pickup tube o-ring? Also, a dab of rtv is needed where the parting line of the front & rear covers meet the oil pan gasket.

Last summer I changed the timing cover gasket, pulley, seal, o-ring, VLOM, etc, etc, etc:
https://www.tahoeyukonforum.com/threads/valley-cover-crank-pulley-etc.149036/

 

[lspann3525]

I havnt installed the updated valve cover yet. I installed new gm pick up tube o-ring and put 4 dabs of rtv where the block meets the covers.

I want to assure its the timing cover gasket sort of hard for me to tell where its coming from. I cleaned that area up during the last oil change so where the leak is coming from its getting worser.

What made you change your timing cover gasket?

 

[donjetman]

I havnt installed the updated valve cover yet.

In 2018 at 130k miles when we bought our road hard and hungup wet Yukon, the piston rings were stuck from sucking & burning oil because of the the poor original valve cover pcv design. Poor pcv performance/vacuum can cause crankcase gaskets to leak due to too much positive crankcase pressure. Today it has 199k miles and does NOT use any oil.

I installed new gm pick up tube o-ring and put 4 dabs of rtv where the block meets the covers.

thats good

What made you change your timing cover gasket?

It had a small oil leak from ?somewhere? on the front of the engine.
The 2 piece pulley balancer is held together with rubber and we all know rubber doesn't last forever so I changed it and the seal.

 

[donjetman]

In 2018, when I had the oil pan off, I also installed the afm valve deflector shield GM# 12639759 ($8) per the TSB instructions, even though my engine is NOT afm equipped.

 

[lspann3525]

Is there an updated aftermarket driver side valve cover?? I was quoted 146 locally..

 

[rdezs]

Here's a link to a set I bought on Amazon for my Hummer H2:

Updated valve covers

Quality was awesome, unbelievable for the price. And they look really good.

 

[lspann3525]

Thanks! Thats a pretty good deal. I will consider this for my gen 3 rebuild. Im going to try to find the cheapest driver side valve cover thats updated to see if that slows down the oil consumption. My oil pan /timing cover seems to be leaking. So ill start with the valve cover

Are all the valve covers with the part number 12570427 updated??

Ebay and Amazon are full of 12570427 aftermarkets that are half the price

Left Driver Side 12570427 Valve Cover For 1999-2008 Cadillac Chevy GMC Pontiac | eBay

Replaces part number: 12570427. 2006-2007 Cadillac CTS V8 6.0L Left Valve Cover. 2004-2005 Cadillac CTS V8 5.7L Left Valve Cover. 2002-2008 Cadillac Escalade Left Valve Cover. 2007-2008 Chevy Avalanche V8 6.0L Left Valve Cover.

www.ebay.com

https://www.amazon.com/JDMSPEED-Replacement-Cadillac-1999-2008-12570427/dp/B09B3N465V/ref=sr_1_1?crid=36DSA0D5DKQ1H&dib=eyJ2IjoiMSJ9.ZJAllszU-vSHHKWAzPoV-6y8__axjp3kYjaCAuqSCEn-S8ysh6k9UVkBXJpE8rhCm1jCmsdKzGTK9buS2ybZZP155C3aUtvVAONozpq0S8csX52tuBqDRT-nYvEQF1XlUzbesOWx3sexNrbfsW6WFQSc6t_tZQJFbcbILexwA1wSfvu0Ew4azWZOTyqgL31aPT2nhrolSzmmjB1Hv0uwCQXHDQISTlG3zHOw6GgEs7kIhEiGrwPIL5p0wB74T_K3a6kL9uKSHpYWSceIapqasjBYoOnYSkQWj6wPmaWKjq93ko8qZ5hQ8w23iT1ZoxK4x2wu-OQTv4XMSfD8bknqc8sabrIjSchqxgUAjPvntAc.zKZeHBLMs0uy85iz2ned4eEvHXxcFgM1yzthcw3g3L0&dib_tag=se&keywords=12570427&qid=1734746235&s=automotive&sprefix=12570427+%2Cautomotive%2C199&sr=1-1

 

[lspann3525]

They all seem to have the rectangle opening instead of the round opening as well.

 

[rdezs]

Did you use the proper tool to center the timing cover when you had it off for the seal? Sort of necessary for the front and rear main seal on LS engines....

Front and Rear Cover Billet Alignment Tool

https://a.co/d/6BYWsUm

 

[rdezs]

.... Also, you'll know that your crank bolt has a rubber coating under the flange to prevent oil seeping out between the harmonic balancer and the crankshaft. If you reused your crankshaft bolt, that could be the culprit as well. It's also worth inspecting your oil cooler lines. They usually start seeping at the factory crimp about the area underneath your power steering pump. Other than that, you have the valley cover gasket and the timing cover gasket itself as well as valve cover gaskets. Don't be surprised if you find your valley cover bolts loose. Pretty common for them to loosen up. New gasket, and I use the blue loctite on the bolts.

 

[lspann3525]

No I didnt use the tool couldnt find one locally and needed to get the truck back on the road. The rear of the pan is dry. I am only seeing the oil build up near the front. sht fck it I went ahead and bought the aftermarket 12570427 seems to be identical to the GM version. Hopefully this will slow my oil consumption down some. Last time I opened the throttle door it was pretty oily so I think my engine had been sucking in oil.

Next time I drop the pan Im going to install the AFM oil deflector. I was hoping I didnt have to change the oil pan gasket again its a challenge changing it on the 4WD trucks but even more extensive dropping the transfer case then the transmission to get at the rear seal.

 

[lspann3525]

.... Also, you'll know that your crank bolt has a rubber coating under the flange to prevent oil seeping out between the harmonic balancer and the crankshaft. If you reused your crankshaft bolt, that could be the culprit as well. It's also worth inspecting your oil cooler lines. They usually start seeping at the factory crimp about the area underneath your power steering pump. Other than that, you have the valley cover gasket and the timing cover gasket itself as well as valve cover gaskets. Don't be surprised if you find your valley cover bolts loose. Pretty common for them to loosen up. New gasket, and I use the blue loctite on the bolts.

The crankshaft bolt has never been removed that I know of but ill give it a look inside the harmonic balancer to see if I can see something. There is no oil cooler there is a block plate on the side of oil pan.

The valve covers have been replaced. They are not leaking at all. Im unable to see the valley gasket. Im leaning towards a timing cover gasket. seeing that around the timing cover crankshaft area its sort of clean but all the outer area is covered.

Is the crank bolt re-usable and if I use a puller to remove the harmonic balancer more than likely its going to seperate so harmonic balancer cant be reused?

Just in case I have a crankcase issue due to the pcv system im going to try that aftermarket cover before I change the gaskets again.

 

[rdezs]

It shouldn't separate. Make sure you're using the correct puller for an LS engine. You want to pull on the center part of the balancer, never on the outer.

I use one of these:

Crankshaft bolt is a torque to yield, and yes you're supposed to use a new one each time.

 

[rdezs]

Most auto parts stores like Amazon have them in there loaner tool collection. They're not that expensive on Amazon.

 

[rdezs]

AutoZone, not Amazon. Damn Google voice

 

[donjetman]

@lspann3525
https://www.tahoeyukonforum.com/threads/crankshaft-pulley-seal-bolt-replace.145675/

 

[lspann3525]

Received the new valve cover and gasket yesterday. I went ahead and changed the oil last night and installed the new valve cover.

Time to put some miles on the truck I'll report back.

 

[rdezs]

Judging from your old valve cover, you have a lot of engine blow by either past the rings or valve seals. Or simply a plugged PCV hose. Should look sort of golden inside. Below picture is an LS 6.0 at 120,000 miles, oil changes every 4,000 miles.

Had another set of heads on the shelf ready to go, and since I was pulling these off to change minor head gasket leak.... Put the other set of heads on with updated valve covers

 

[j91z28d1]

I agree that's a bit ugly inside. feels like it might be a good one to try the ring cleaning donjetman did to his?

or atleast might be a good candidate to test that new restore and protect cleaning oil on?