Small Block Rear Seal Replacement
Thread Starter
Racer
Joined: Mar 2005
Posts: 294
Likes: 1
From: Racine Wisconsin
Small Block Rear Seal Replacement
Someone suggested to me that the rear oil seal could be replaced without removing the engine from the vehicle. This seems a little too easy to me. The particular oil leak is the only engine problem I have right now and I would like to avoid pulling the engine just for this. I am willing to tackle the job. What is involved? Should I use the stock GM part or is there a better after-market part?
Thanks,
Ken
Thanks,
Ken
Burning Brakes
Joined: Sep 2001
Posts: 1,166
Likes: 0
From: Tulsa Ok
I've done it once on a Ford truck with the engine in. Not a big deal for a wrencher. You'll have to pull the tranny of course and oil pan which means dropping the steering arm to get it out of the way. Once you've pulled the clutch and flywheel you'll need to loosen the bearing caps enough to drop the crank about 3/8" to provide clearance to the seal. the top seal needs to be inserted veeery carefully to avoid sculling the edge and rendering all this work in vain. I offset the top seal about 1/8" and used a little RTV on the mating surfaces. Now is also a good time to inspect your rod and main bearings and replace if they show wear.
Stock replacement part is fine.
Stock replacement part is fine.
Safety Car
Joined: Oct 2000
Posts: 3,547
Likes: 12
From: Carbondale Pa.
are you sure?
Hi, I did this job quite a while back and I dont remember pulling anything but the oil pan, I was thinking it was very close quarters to work in but I know I didnt pull the trans or the bell housing, this was on a '71 LT-! conv that I once had. As suggested I did offset the mating surface of the seal when I put it back together etc. Good luck Peace,,,Craig 
Burning Brakes
Joined: Sep 2001
Posts: 1,166
Likes: 0
From: Tulsa Ok
Good to know its possible with the flywheel in place. I imagine the PITA factor of pulling all those parts would be offset by the tight space you'd have to deal with. Ain't a easy chore either way, but do-able. 
Race Director
Joined: Feb 2005
Posts: 16,100
Likes: 17
A friend just did this on his Cherokee,along side the hwy in Yuma...he had to pull tranny back a little...used rocks to prop tranny in place..and used a coat hanger to feed seal in ...
He had an automatic...
He had an automatic...
Le Mans Master
Joined: Jul 2005
Posts: 5,752
Likes: 4
From: Austin Texas
Originally Posted by 7T3C3TTZ07
Someone suggested to me that the rear oil seal could be replaced without removing the engine from the vehicle. This seems a little too easy to me. The particular oil leak is the only engine problem I have right now and I would like to avoid pulling the engine just for this. I am willing to tackle the job. What is involved? Should I use the stock GM part or is there a better after-market part?
Thanks,
Ken
Thanks,
Ken
Pro
Joined: Mar 2005
Posts: 559
Likes: 0
From: James Island South Carolina
I just dropped the pan to replace my rear seal. Didn't have to pull anything else. It's been a little while and I can't quite remember if I had to loosen the mounts, and lift the engine a little to clear the pan. (It seems like I've done that so many times for so many tasks). It's not a horrible job, but it takes a bit of time. A helpful friend always makes a big difference with any job. Good luck.
Safety Car
Joined: Jul 2001
Posts: 3,921
Likes: 2
From: York PA
I've done it. Just drop the pan and remove the bearing cap. Be careful installing the new seal. I had to do it 2 times. The first one came with a gasket set and didn't come with plastic tabs to protect it when I pushed it in. Needless to say it leaked worse than to old one. I got another seal from the local parts store and it came with a plastic tab that protects the seal as you install it. Also don't over tighten the oil pan as you put it back on 
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Melting Slicks
Joined: Mar 2005
Posts: 2,093
Likes: 297
From: Midlothian VA
Just did this two weeks ago. Drop the steering (easiest to do if you simply unbolt the idler arm from the frame) so the oil pan can be removed. Pull the oil pump, and the rear main cap. Once the cap is off the lower cap seal is no problem. Hardest part is getting the upper seal to slide around the crank. I used a very small screwdriver (an old oil dipstick works well too) to loosen the seal as far up as I could without damaging the crank journal. Then tap on one side of the upper seal using a brass drift and the seal should roll around the crank enough for you to pull it out with needle nose pliers. Sliding the new one in is cake (make sure you have it facing the correct way). Then reverse the rest of the parts and you're in business. Don't forget to lightly lube the seal lip and get yourself a one piece pan gasket if you can (search other posts on this topic), it will make you life easier in the long run.
Last edited by Hammerhead Fred; Aug 8, 2005 at 11:21 AM.
Drifting
Joined: Aug 2004
Posts: 1,327
Likes: 5
From: 2010 C6 Grand Sport Convertible
Originally Posted by rihwoods
A friend just did this on his Cherokee,along side the hwy in Yuma...he had to pull tranny back a little...used rocks to prop tranny in place..and used a coat hanger to feed seal in ...
He had an automatic...
He had an automatic...
Mike
Race Director
Joined: Feb 2005
Posts: 16,100
Likes: 17
Originally Posted by 78pacer
Gheeesh! I thought replacing wiper blades in an AutoZone parking Lot was the pits! He musta been dumping out oil like he had a rock thrown threw his pan.
Mike
Mike
Le Mans Master
Joined: Oct 2001
Posts: 5,943
Likes: 3
From: Wildwood IL
Originally Posted by Hammerhead Fred
Just did this two weeks ago. Drop the steering (easiest to do if you simply unbolt the idler arm from the frame) so the oil pan can be removed. Pull the oil pump, and the rear main cap. Once the cap is off the lower cap seal is no problem. Hardest part is getting the upper seal to slide around the crank. I used a very small screwdriver (an old oil dipstick works well too) to loosen the seal as far up as I could without damaging the crank journal. Then tap on one side of the upper seal using a brass drift and the seal should roll around the crank enough for you to pull it out with needle nose pliers. Sliding the new one in is cake (make sure you have it facing the correct way). Then reverse the rest of the parts and you're in business. Don't forget to lightly lube the seal lip and get yourself a one piece pan gasket if you can (search other posts on this topic), it will make you life easier in the long run.
Exactly how it's done on an older small block. Just be sure to torque the bearing cap & oil pump to specs. You might consider replacing the $1.00 plastic oil pump shaft connector while your in there.... Carefull of the oil pump pick up so ya don't bend, twist, or damage it.Eddie
Burning Brakes
Joined: May 2004
Posts: 1,100
Likes: 3
From: belle plaine ks
Rear main seal
Being an old line mechanic [over thirty years ago] the drill is that most oil pans come off and you service the seal in the car. Exception was the Chevelle. You had to pull the motor. That being said we were required on Warranty work to plastigage the rear main. If the clearance was too great you put in .001, .002, or.003 rear main bearings along with the rear main seal. This tightened the bearing clearance and helped to control oil leaks as well. These different sized rear mains were available from GM, but I don't know if they still are. But once again you have to pick the bearing size based on the plastigage reading. Also we used silicone spray and or lubriplate to coat seal. Where you lose most seals is from not lubricating the lip. On start up against a dry seal you will "burn the lip" [glaze actually] the seal and you are no better off than before you decided to fix the leak. The reason I know all this, is a lot of customers would not put up with an oil spot in their driveway when a car was under warranty. So you learned fast what worked and what didn't 
