Bad Oil Leak - The 1947 - Present Chevrolet & GMC Truck Message Board Network

1984Silverado4x4 · 05-20-2008, 04:49 AM

My brother has a 1984 C10 with the 305 and we've replaced the rear main seal twice now because it leaks oil so badly out of the little hole in the bottom of the torque convertor cover.

We made sure to RTV everything good and we put a one piece rubber gasket on the oil pan and it still leaks like crazy. As soon as you stop a puddle starts to form under the truck. We used a 2 piece rear main seal.

Did we do something wrong when we replaced the seal or could it be something else thats leaking?

bowtiecb · 05-20-2008, 06:53 AM

did you make sure the pan wasnt bent or not making a good seal

89 crew · 05-20-2008, 06:57 AM

There are two possibilities. first the mains are loose and because of the crank jumping around it is beating the new seal out. The second possibility is the surface the seal rides on is damaged. I don't know about for cranks, but for axles there are metal sleeves that you can press on to make the surface like new.

piecesparts · 05-20-2008, 04:22 PM

ALSO check the oil galley plugs in the block above the crank seal. Are you sure it is not leaking out of the valve cover or the intake manifold and running down th eblock to the starter opening and thenout of the hole inthe bottom of the flywheel cover. I had one do that before.

mhicks · 05-20-2008, 04:35 PM

That is what I had on mine, it was leaking from the back of the intake.

babyJay · 05-20-2008, 07:03 PM

Also, check the oil pressure sending unit right behind the dissy at back of the intake. Usually when those leak they leak really bad. Just not sure if it would come out your dust cover tho, usually it'll drip off something else.

1984Silverado4x4 · 05-20-2008, 08:18 PM

I will have to take a closer look but I pretty sure the oil is only coming out of the Torque convertor cover

slugish · 05-21-2008, 06:15 AM

Ditto , Same problem for me for years. oil coming out of dust pan cover . havent seen any leaks anywhere else. Those damn 2 pc seals (Iguess)

us111 · 05-22-2008, 02:34 AM

a lot of other oil leaks like mentioned above will
run straight into that cover and out the hole.mine
was an intake leaking in the rear.good luck

Damien · 05-23-2008, 05:41 AM

The oil pressure sender on my truck was leaking and running down the outside of the dust cover and dripping at the hole in the dust cover. Good luck.

05-20-2008, 04:49 AM	#1
1984Silverado4x4 Registered User Join Date: Jul 2007 Location: Mount Horeb WI Posts: 179	Bad Oil Leak My brother has a 1984 C10 with the 305 and we've replaced the rear main seal twice now because it leaks oil so badly out of the little hole in the bottom of the torque convertor cover. We made sure to RTV everything good and we put a one piece rubber gasket on the oil pan and it still leaks like crazy. As soon as you stop a puddle starts to form under the truck. We used a 2 piece rear main seal. Did we do something wrong when we replaced the seal or could it be something else thats leaking? __________________ Its no disgrace being poor. Its just inconvenient.

05-20-2008, 06:53 AM	#2
bowtiecb Registered User Join Date: Oct 2006 Location: alabama Posts: 79	Re: Bad Oil Leak did you make sure the pan wasnt bent or not making a good seal

05-20-2008, 06:57 AM	#3
89 crew Registered User Join Date: Mar 2006 Location: Kansas Posts: 865	Re: Bad Oil Leak There are two possibilities. first the mains are loose and because of the crank jumping around it is beating the new seal out. The second possibility is the surface the seal rides on is damaged. I don't know about for cranks, but for axles there are metal sleeves that you can press on to make the surface like new.

05-20-2008, 04:22 PM	#4
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	Re: Bad Oil Leak ALSO check the oil galley plugs in the block above the crank seal. Are you sure it is not leaking out of the valve cover or the intake manifold and running down th eblock to the starter opening and thenout of the hole inthe bottom of the flywheel cover. I had one do that before.

05-20-2008, 04:35 PM	#5
mhicks Registered User Join Date: Jan 2004 Location: Weatherford,Tx Posts: 747	Re: Bad Oil Leak That is what I had on mine, it was leaking from the back of the intake.

05-20-2008, 07:03 PM	#6
babyJay Arrived on a Pale Horse Join Date: Mar 2007 Location: SnagTown Indiana Posts: 2,524	Re: Bad Oil Leak Also, check the oil pressure sending unit right behind the dissy at back of the intake. Usually when those leak they leak really bad. Just not sure if it would come out your dust cover tho, usually it'll drip off something else. __________________ Jason 87 V30 350TBI/400 White w/Boss V-plow 89 R3500 CC SRW Last edited by babyJay; 05-20-2008 at 07:04 PM.

05-20-2008, 08:18 PM	#7
1984Silverado4x4 Registered User Join Date: Jul 2007 Location: Mount Horeb WI Posts: 179	Re: Bad Oil Leak I will have to take a closer look but I pretty sure the oil is only coming out of the Torque convertor cover __________________ Its no disgrace being poor. Its just inconvenient.

05-21-2008, 06:15 AM	#8
slugish Slugish Join Date: Jan 2005 Location: Earlysville, Va. Posts: 1,024	Re: Bad Oil Leak Ditto , Same problem for me for years. oil coming out of dust pan cover . havent seen any leaks anywhere else. Those damn 2 pc seals (Iguess)

05-22-2008, 02:34 AM	#9
us111 Registered User Join Date: Jul 2004 Location: ashland oh Posts: 660	Re: Bad Oil Leak a lot of other oil leaks like mentioned above will run straight into that cover and out the hole.mine was an intake leaking in the rear.good luck

05-23-2008, 05:41 AM	#10
Damien Registered User Join Date: Mar 2007 Location: Farmington, MN Posts: 928	Re: Bad Oil Leak The oil pressure sender on my truck was leaking and running down the outside of the dust cover and dripping at the hole in the dust cover. Good luck. __________________ I can still count my vehicles on two... wait three hands.



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