In your opinion....oil pan gasket or rear main seal

[DetroitIron]

Finally identified the area of my oil leak...pulled the trans flex plate and wiped oil pan and everything down....then watched the garage floor for couple days. I have small oil drip EITHER from the rear main OR the rear oil pan lip/gasket area(just below the rear main seal). Before going any further dropping the oil pan or even more fun sliding trans/transfer case back, I thought I would check with the experts on here for any visual tips in determining the source. btw I have check oil sending and rear intake gasket area. The pan and one piece gasket was replaced just recently...so I'm leaning towards rear main, but it's such a small leak (fifty cent piece size spot on garage floor after two days...i thought rear main seal would leak much more when they go) I don't know if the rear main seal is the culprit or whether oil pan gasket at the rear hump isn't sealing 100%....Any suggestions? Thanks Guys!!

[moneyeater]

Hey detroitiron,
i´m facing the same problem + leaking valvecovers + intakebolts!
I´ll just watch what the experts say! I think changing the rear main seal is no walk in the park, right? I have all the seals and gaskets laying in my shelf but to change all them it would be best to pull the motor out!
Volker

[78 Chevyrado]

I'd buy one of those 1 piece oil pan gaskets and change that only. then if it still leaks from the main seal, you'll know about it and the new oil pan gasket it re-usable so then you can remove it to fix the main and not lose money on yet another pan gasket.

You can change a rear main in the truck. you just remove the pan and take off the rear main bearing (carefully so as not to upset the way the bearings are in there.

If the pan wont come off because it hits the crankshaft, youll have to rotate the crank by hand until you get it to a spot where the pan clears.

[DetroitIron]

Thanks Guys! I needed to get my plow moved to the shop for a pre-season check....so I guess the oil leak fix will wait for now...plus I may pull the engine in the Spring to update a few things. Thanks Again!

[moneyeater]

Talked to a specialist today and he told me that it is nearly impossible to get the two piece rear main seal dry because of its design! when an engine stands still a longer time the seal adheres to the crank and when the crank turns material is ripped of the seal and it´ll leak!
He also said that the onepiece Oilpangaskets are expensive but worth the price!
I´ll get my motor out the truck later the year and make him change all the seals and gaskets. Spending a little more on quality parts is the way here!
Volker

[turner16]

I disagree, mine sat for 18 years and it was the oil pan. The 1 piece oil pan gasket is amazing, pricey but what a fit. Even got new bolts with it.