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73-87 Chevy _ GMC Trucks => 4 Wheel Drives => Topic started by: Silver78ado on May 26, 2005, 09:06:00 pm

Title: Rear main seal?
Post by: Silver78ado on May 26, 2005, 09:06:00 pm
I took the beast for a drive today after work..my 78 K10..i took it to the store i came back out and just happen to look under the truck ..oil was leaking out between the back of the block and trans..it was dripping pretty fast..has any one ever changed there rear main whith the block still in the truck..its a 400 is this a one peice seal or two ..any help would be great..thanks yall.

Title: Re: Rear main seal?
Post by: roundedline on May 26, 2005, 11:10:00 pm
400 SBC's were 2 piece seals.  I have changed mine in the truck before.  Heck, I replaced a rod and piston with it in the truck before.

Chris Lucas
www.73-87chevytrucks.com
www.captkaoscustoms.com
Project Su
Jimmy 2WD Project

Title: rear main seal
Post by: Lt.Del on May 27, 2005, 10:59:00 am
It is not as hard as you may believe it to be.  I did one about a month ago.  The hardest part is dealing w/ the oil pan...even that isn't hard if you take your time.  

I didn't have to remove starter either.  Just take the pan off, all one thousand little bolts.  That is after you drain the oil!!

Take the oil pump off to get access to the rear main.  You will be getting splatted w/ lots of oil because the oil never stops dripping.  Wear old clothes!

Take the rear main off.  Slide the old seal out of the rear main cap.  Gingerly take the old seal out of the block.  I used needle nose pliers and a screwdriver, but be sure not to scratch the crank or you'll be sorry.  PUsh up on one side, then grap the other side when enough comes thru and pull it out.  

Take the new seal and coat it w/ oil.  Be sure the lip groove faces front of engine.  Easily slide it up into the block around the crank.  There is no need to loosen up the other bearing caps.  I didn't have to.  

Place the bottom seal in the rear cap and reattach.  I torqued my  bolts to 65 foot lbs.  You may want to replace your oil pump ...they are cheap.

when reinstalling the oil pump, ensure the rod from distributor goes in correctly.   While the pan is off, check torque on all other bearing caps...65 ft lbs.

Now the frustrating part, put that pan back on w/ out moving the gasket!  i use fishing string to tie a few bolt holes to the gasket so it wont move.  Ensure you have gasket sealer at the corners of the gasket where the bends wrap around the crank.  

Your starter cable should be connected to one of these pan bolts as well as a bracket holding the transmission lines together if you have an automatic.  

It really isn't hard to do, just take your time and do not scratch your crank when removing / installing the seal.  

Andy
www.delbridge.net


 

Title: Re: rear main seal
Post by: roundedline on May 27, 2005, 11:03:00 am
Is the pan gasket leaking or the rear seal?

I usually push the crank seal out with its matching pair.

For the gasket problem, I use a very thin skim of silicone on the block and stick the gasket to the block.

Chris Lucas
www.73-87chevytrucks.com
www.captkaoscustoms.com
Project Su
Jimmy 2WD Project

Title: Re: rear main seal
Post by: VileZambonie on May 27, 2005, 04:28:00 pm
3M weatherstripping adhesive is the best stuff to use. It'll hold your gasket in place while you put the pan up. RTV in the 4 corners is a good idea too. Before you do all of this make sure the back of the intake or base of the distributor isn't wet.

Title: Re: rear main seal
Post by: Silver78ado on May 27, 2005, 04:58:00 pm
i guess i need to remove the dust cover ,to see if it is the pan or the main seal..looking at it from top side the back top of the intake appears to be ok but i will check it out better..i did have the intake off last winter when it blew a head gasket maybe the gasket on there is out of whack.but it hasnt leaked untill now..thanks yall..i will keep you posted.

Title: Re: rear main seal
Post by: Blazin on May 28, 2005, 06:13:00 pm
The 3M weatherstrip adhesive trick works great I learned that a long time ago. You can also my Fel Pro reusable gaskets they are bright blue and have a nice lip that fits onto the pan so you can put it up in and the gasket wont fall off. I used one in my 86.

Title: Re: Rear main seal?
Post by: David Hall on December 15, 2008, 05:38:17 am
The seal ends should be staggered and not flush with the block or rear bearing cap.
Title: Re: Rear main seal?
Post by: bigkountry on December 15, 2008, 10:05:05 am
It's been 3 1/2 years..I hope he's gotten it fixed by now...lol
Title: Re: Rear main seal?
Post by: VileZambonie on December 15, 2008, 10:08:51 am
Right.  :o
Title: Re: Rear main seal?
Post by: Captkaos on December 15, 2008, 11:01:09 am
There is a reminder that pops up for all old post I really don't see HOW/Why these are brought up...
Title: Re: Rear main seal?
Post by: ccz145a on December 15, 2008, 11:05:58 am
Have mercy on the newbies. A gentle kick in the gut will do ;D