oil leak - Crankshaft Front Seal

ubejd · Oct 7, 2024

hi
my 2004 yukon denali with nearly 200000 miles started a oil leak from the seal.
i think it came after i had an engine overheat to around 240-250.

what i did trying to fix it:
1. changed the seal ( gm seal) - still leaking
2. changed the seal again just to make sure the first seal wasnt damaged - still leaking
3. changed the front cover and Harmonic Balancer with new seals and gaskets - still leaking

the engine has low pressure oil, when cold 40 psi but it will drop to around 10 psi when idling and hot, when accelerating it goes up again.
i changed the pick up tube o ring but still the same.

i did some research and i might have bad cam bearing but fix it not in the budged right now, so my question is there anything else i can try to fix this issue before tearing the engine apart.

strutaeng · Oct 7, 2024

Did you check the harmonic balancer snout (the part that rides inside the seal) for any wear? I'm not sure if those wear like on the old SBC, but maybe that's your issue? I tore down my LQ4 for a refresh a few months ago and it was fine on mine, with 260k miles.

As far as low oil pressure, just switch to 40 or 50 weight oil and keep on truckin'. If you don't have any knocking or rattling, that will increase your oil pressure a few psi. Just keep running it...

justirv · Oct 7, 2024

ubejd said:
hi
my 2004 yukon denali with nearly 200000 miles started a oil leak from the seal.
i think it came after i had an engine overheat to around 240-250.

what i did trying to fix it:
1. changed the seal ( gm seal) - still leaking
2. changed the seal again just to make sure the first seal wasnt damaged - still leaking
3. changed the front cover and Harmonic Balancer with new seals and gaskets - still leaking

the engine has low pressure oil, when cold 40 psi but it will drop to around 10 psi when idling and hot, when accelerating it goes up again.
i changed the pick up tube o ring but still the same.

i did some research and i might have bad cam bearing but fix it not in the budged right now, so my question is there anything else i can try to fix this issue before tearing the engine apart.

By chance did you use a timing cover alignment tool? LS's are sensitive that way on both the front and rear main seals.

ubejd · Oct 7, 2024

1. no i didnt check it, i will if i have to pull it out again.
i mentioned the issue with low oil pressure because it might be related to cam bearings too, even thought it might be the oil pump, no knocking or ticking noises until now.

2. nope, i dodnt have that tool, i did use the oil pan method some youtubers i saw doing it.

Fless · Oct 7, 2024

For the oil pressure issue, has the oil pickup tube o-ring ever been replaced?

rockola1971 · Oct 7, 2024

I would expect lots of glitter in your oil if your cam bearings were bad and also lots of valvetrain noise. Did you verify that you have no coolant in your oil? Could have blown a head gasket from the overheat incident. Verify you dont have an unusually large amount of bubbles/air come into your overflow tank upon engine startup. Does your engine warmup unusually fast now as witnessed by the temp gauge?

ubejd · Oct 8, 2024

I did change the oil pickup tube o-ring, and i will change the oil pressure sensor too in a couple days just to rule it out.

the oil has now 3k miles it has the color of an used oil.
the coolant is level didnt drop but i will check for bubbles.
i live in a hot climate region so i bit difficult to pinpoint .

thanks for your inputs.

update: no bubbles - checked the car 2-3 times, cold start and hot too.
update 2: changed the engine oil, no foaming or color changing.

oil leak - Crankshaft Front Seal

ubejd

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strutaeng

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justirv

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ubejd

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Fless

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