oil pan gasket headaches - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Tom · 02-13-2020, 06:59 PM

My trucks been leaking oil for a while. A few months ago, I changed the pan gasket. Leak continued and I realized it was the timing cover. So I changed the cover the other day and did the pan gasket again since I had to drop it to do the cover. It would leak around the rear main area once I turned the truck off. Thought I must have messed something up, so I did it again. Gasket broke coming off so yet another brand new one went on. And its leaking from the rear main area with the truck off yet again. What in the world could I be getting wrong? I used RTV at the corners per the instructions.

**Palf70Step** · 02-14-2020, 08:35 AM

I don't think I have ever had an older 350 that would not leak some there. But, with that said I have never changed one with the newer one piece main seals. I wonder if you need to change that also?

Tom · 02-14-2020, 05:26 PM

You have to remove the trans to do the rear main seal. Its not leaking from there from what I can tell, and the oil pan gasket doesn't have anything to do with the rear main seal. It also didn't start until I changed the pan gasket a couple days ago. Its not leaking a little, its leaking a large puddle when I turn the truck off.

vht · 02-15-2020, 07:05 PM

If it is the rear main seal, it's most likely getting in the flywheel shield or cover and then leaking out from there when you shut it off.

02-13-2020, 06:59 PM	#1
Tom driving is in my blood Join Date: Dec 1999 Location: Mesa AZ Posts: 5,692	oil pan gasket headaches My trucks been leaking oil for a while. A few months ago, I changed the pan gasket. Leak continued and I realized it was the timing cover. So I changed the cover the other day and did the pan gasket again since I had to drop it to do the cover. It would leak around the rear main area once I turned the truck off. Thought I must have messed something up, so I did it again. Gasket broke coming off so yet another brand new one went on. And its leaking from the rear main area with the truck off yet again. What in the world could I be getting wrong? I used RTV at the corners per the instructions. __________________ -78 c10 short/step: 388cid, M20, 5/5 drop, lots more. Playtoy and first vehicle. -98 c1500 x-cab: 5.7L, 17" rims, 5/6 drop, flowmaster, helper bags,NBS rear disk brakes. -02 Suburban 4x4: leveled front -CBR600F4i, CBR600RR, CBR1000RR, and standup skis DISCLAIMER: I cant spell for the life of me.

02-14-2020, 08:35 AM	#2
Palf70Step State of Confusion! Join Date: Jul 2002 Location: Gulfport, MS USA Posts: 46,643	Re: oil pan gasket headaches I don't think I have ever had an older 350 that would not leak some there. But, with that said I have never changed one with the newer one piece main seals. I wonder if you need to change that also? __________________ Bill 1970 Chevy Custom/10 LWB Fleetside 2010 Toyota Tacoma PreRunner SR5 Double Cab - DD Member of Louisiana Classic Truck Club (LCTC) Bill's Gallery Life isn't tied with a bow, but it's still a gift. Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God!

02-14-2020, 05:26 PM	#3
Tom driving is in my blood Join Date: Dec 1999 Location: Mesa AZ Posts: 5,692	Re: oil pan gasket headaches You have to remove the trans to do the rear main seal. Its not leaking from there from what I can tell, and the oil pan gasket doesn't have anything to do with the rear main seal. It also didn't start until I changed the pan gasket a couple days ago. Its not leaking a little, its leaking a large puddle when I turn the truck off. __________________ -78 c10 short/step: 388cid, M20, 5/5 drop, lots more. Playtoy and first vehicle. -98 c1500 x-cab: 5.7L, 17" rims, 5/6 drop, flowmaster, helper bags,NBS rear disk brakes. -02 Suburban 4x4: leveled front -CBR600F4i, CBR600RR, CBR1000RR, and standup skis DISCLAIMER: I cant spell for the life of me.

02-15-2020, 07:05 PM	#4
vht Registered User Join Date: Jun 2013 Location: Brooksville Ky Posts: 531	Re: oil pan gasket headaches If it is the rear main seal, it's most likely getting in the flywheel shield or cover and then leaking out from there when you shut it off.



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