Rear Main seal replacement on 72 Chevy - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Momboy007 · 01-06-2009, 05:28 PM

Hello All,
It seems the rear main seal is leaking pretty badly on the 72 Chevy Pick up, 1/2 ton with 350 motor and 350 Turbo transmission. What is the best way to replace this, is there a best known method for replacing this seal?
Thanks all in advance,
Rick

Tx Firefighter · 01-06-2009, 06:58 PM

Drop the oil pan and oil pump, remove the rear main bearing cap, fish the old seal half out and spin the new one in place.

Sounds easy when you say it like that doesn't it ?

Basically, you have to use a blunt curved tool to slide the upper seal half out of the block and the new one into place. It can be a bear if it's old and stuck.

Momboy007 · 01-06-2009, 07:27 PM

Hey TX,
Can I drop the pan without removing cross members etc...?
Thanks for your help
Rick

Sinister · 01-06-2009, 07:35 PM

Yes, you have to undo your motor mounts, jack or lift the motor, then put some 2 x 4's where the motor mounts are. You might have to turn the crank to clear the pan.

C20_Paul · 01-06-2009, 07:56 PM

If you have a one-piece seal you'll have to separate the engine and trans to get it out. If yours is a two-piece do what TX_Firefighter said.

If you have the two-piece you may have to jackup the engine in order to slide the oil pan out from between the engine and the crossmember. Just unbolt the motor mounts and pick the engine up by something other than the oil pan and you are in business.

I'd also recommend switching to a one piece oil pan seal while you have it all apart.

Tx Firefighter · 01-06-2009, 08:20 PM

If you wind up having to jack the engine up off of the mounts, do two things, trust me here. One, unbolt the fan shroud from the radiator. Two, remove the distributor cap and lay it aside somewhere.

You will break one or both of them if you don't.

01-06-2009, 05:28 PM	#1
Momboy007 Registered User Join Date: Mar 2008 Location: Southern California Posts: 82	Rear Main seal replacement on 72 Chevy Hello All, It seems the rear main seal is leaking pretty badly on the 72 Chevy Pick up, 1/2 ton with 350 motor and 350 Turbo transmission. What is the best way to replace this, is there a best known method for replacing this seal? Thanks all in advance, Rick

01-06-2009, 06:58 PM	#2
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	Re: Rear Main seal replacement on 72 Chevy Drop the oil pan and oil pump, remove the rear main bearing cap, fish the old seal half out and spin the new one in place. Sounds easy when you say it like that doesn't it ? Basically, you have to use a blunt curved tool to slide the upper seal half out of the block and the new one into place. It can be a bear if it's old and stuck. __________________ I'm on the Instagram- @Gearhead_Kevin

01-06-2009, 07:27 PM	#3
Momboy007 Registered User Join Date: Mar 2008 Location: Southern California Posts: 82	Re: Rear Main seal replacement on 72 Chevy Hey TX, Can I drop the pan without removing cross members etc...? Thanks for your help Rick

01-06-2009, 07:35 PM	#4
Sinister Between Trucks... Join Date: Mar 2002 Location: Los Angeles, CA. Posts: 3,830	Re: Rear Main seal replacement on 72 Chevy Yes, you have to undo your motor mounts, jack or lift the motor, then put some 2 x 4's where the motor mounts are. You might have to turn the crank to clear the pan. __________________ Beat it to fit, Paint it to match...

01-06-2009, 07:56 PM	#5
C20_Paul Registered User Join Date: Jul 2007 Location: Portland, OR Posts: 35	Re: Rear Main seal replacement on 72 Chevy If you have a one-piece seal you'll have to separate the engine and trans to get it out. If yours is a two-piece do what TX_Firefighter said. If you have the two-piece you may have to jackup the engine in order to slide the oil pan out from between the engine and the crossmember. Just unbolt the motor mounts and pick the engine up by something other than the oil pan and you are in business. I'd also recommend switching to a one piece oil pan seal while you have it all apart.

01-06-2009, 08:20 PM	#6
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	Re: Rear Main seal replacement on 72 Chevy If you wind up having to jack the engine up off of the mounts, do two things, trust me here. One, unbolt the fan shroud from the radiator. Two, remove the distributor cap and lay it aside somewhere. You will break one or both of them if you don't. __________________ I'm on the Instagram- @Gearhead_Kevin



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