5.3 very persistent oil leak

[Oskar Häggdahl]

Hey there guys. New to this forum...

Before you say this is a rear main leak, please read below!

 

Having an annoying issue with a persistent oil leak on a 2002 Suburban 5.3 with 220k miles.

It was initially diagnosed as a rear main leak, but when taking it into the mechanic he says it’s not. We’ve changed the oil pan gasket twice, and the gasket to the block off for oil cooler lines, new valve cover gaskets, new oil pressure sensor, checked crank sensor and cam sensor. 

The flywheel and back rear plate is dry.

 

The truck won’t leak if I drive. The more I drive, the less it leaks. If I drive for 4-5 hours and park it it won’t leak. But if I don’t drive for a few days it’ll start leaking immediately upon startup, and then stop after driving for a few hours. 

If when I’m away I park the truck for a week or two, it’ll leak a lot immediately upon startup.

It’s not burning oil and won’t need to be filled up if I drive a lot, but if it sits I’ll have to refill 0.25 quarts if it sits for a week. Or if all I do is do short drives around town. 

 

I’ve looked into valley pan, but it doesn’t seem to come from up top. 

It’s wet by the bottom of the pan and the rear pan bolts, and starter bolts. By the bottom of the bell housing. Seems like it’s dripping from the rear pan bolts.

 

Got a brand new (OEM) oil pressure sensor and a new o-ring for the oil pickup tube. At cold idle oil pressure is 65psi, warm idle is about 45psi.

 

This is driving me nuts... and my mechanic is at a loss. We don’t want to pull the transmission and do the rear main since it doesn’t seem to be coming from there...

 

Any thoughts??

 

Much appreciated! Thanks!

[Jglew82]

The rear cover that houses the rear main seal has been updated. Mine was leaking from the same spot. https://www.amazon.com/Genuine-GM-12639250-Crankshaft-Housing/dp/B00F677EHE/ref=pd_cp_263_2?pd_rd_w=cnVFm&pf_rd_p=ef4dc990-a9ca-4945-ae0b-f8d549198ed6&pf_rd_r=RPQN8R9QN3KTWMXNKAT6&pd_rd_r=68a6ccda-e334-4af6-a784-17b5ca4be777&pd_rd_wg=bVEqb&pd_rd_i=B00F677EHE&psc=1&refRID=RPQN8R9QN3KTWMXNKAT6 

[sefiroxx]

Try some florescent dye

[txab]

Did you check the crank sensor that is mounted above the starter. It can leak. Results show up in the area you referenced.

Oh, as noted above, dye would be good to use