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Oil Pan gasket or rear main seal

minifridge1138

Well-known member
Joined
Feb 2, 2007
Messages
908
Location
USA
Corvette
1982 Black Fastback
Hey everyone,

My car has an oil leak.
The oil is dripping down through the hole in the flex plate cover.

I assume, that a leaky oil pan gasket could cause this, but could I also have a leaky ream main seal?

Is there a way to test the rear main seal and find out?

No matter what, I need to drop the oil pan to replace that gasket. But should I also replace the rear main seal? If it is leaking a little, wouldn't that just drip into the oil pan?
 
Hey everyone,

My car has an oil leak.
The oil is dripping down through the hole in the flex plate cover.

I assume, that a leaky oil pan gasket could cause this, but could I also have a leaky ream main seal?

Is there a way to test the rear main seal and find out?

No matter what, I need to drop the oil pan to replace that gasket. But should I also replace the rear main seal? If it is leaking a little, wouldn't that just drip into the oil pan?
You can take the fly wheel cover off and look and maybe see if it's comeing from the back of the pan but my guess is the main seal needs replaced!! If I went to the trouble to change the pan gasket I'd change the seal and check a couple bearings with plasta-gauge anyway!:thumb:thumb:thumb
 
I'm with the Junkster....probably a rear main seal but also, if the stuff is redish-brown, it might be the trans front seal.
 
I also have the exact same oil drip as you described. Pretty sure it is the rear main seal as the pan gasket seems to be okay. It is just a small regular oil drip. Not looking forward to replacing!! good luck with yours
 
Mine was dripping where yours is as well as a couple of other places underneath. I had 2 problems: (1) passenger side valve cover gasket, and (2) oil pan gasket. Also, the oil pan's gasket flange area had a small dent just in front of the oil filter. I very carefully worked the dent out of the oil pan gasket flange and replaced the leaking gaskets. I now have no oil leaks. Used a Fel-Pro 1-piece rubber oil pan gasket and Fel-Pro Premium Molded Rubber valve cover gaskets.

Good luck!
Jerry
 
. Used a Fel-Pro 1-piece rubber oil pan gasket and Fel-Pro Premium Molded Rubber valve cover gaskets.

Good luck!
Jerry

I have used a few of these Fel-Pro one piece gaskets and will never use anything else again. They even come with 4 plastic do dads that hold the gasket in place while you are installing the pan if you are working overhead (engine in the car). There is also a rear main seal available from NAPA (Victor I think) that has an offset sealing lip in case your crank journal has a slight groove worn in it. The new seal will seal against unworn journal surface.

Tom
 
I also use Felpro and haven't had a problem. It's also time for me to change rear main seal ,,,,can't wait :puke
 
I did this write up a while back and posted it on another Corvette web forum. One of the members there complained that he was actually the one that took the pictures I used so I deleted it from that forum.
Anyway, I've changed a large pile of rear seals over the years- this works.


Basic, easy to follow, do it once rear main seal change.

Once you have the pan down, remove the oil pump and pickup. Remove the rear main cap. The lower half of the seal is right there. Don't scratch the bearing. Take a small screwdriver and pop the lower half out of the cap, then use the screwdriver, (I have one that I did a little bit of grinding on so it's got a better flat end) and push on the exposed end of the upper half of the seal. You may hve to tap it a little bit to break the upper seal loose. Drive it out until you can get a good grip on it and then just walk it on out. Now the old seal is out, clean the block and the seal groove with something like brake cleaner, just hose it out really well.

The trick part is next. GM and the aftermarket have 3 different widths of rear seals. The difference in them is from the dust lip on the back to the wiper lip on the forward side of the seal. The best (and widest one) is the one you need to find. The biggest distance between the two lips. You may have to hunt for it. GM had them all under the same part number, but there are different ones. The side of the seal that is "UP" in this picture is the "FRONT"
3442904_L.jpg



Take the rear main cap to your bench grinder and use the wire wheel on the mating surfaces adjacent to the seal. Look at the second picture. Where you want to buff the cap is where the sealant is applied. Don't get so far forward to catch the bearing. Buff the cap, get it really clean. Then hose it down with the brake cleaner too. Let it dry while you install the upper half of the seal.

rearmainseal1.jpg




In the package there is a little plastic "spoon". Use it to install BOTH the upper and lower halves. Put a little bit of grease on the lips of the upper seal. If you don't, the rib on the inside of the seal gets sliced off and will seep underneath the seal.

Once you have the lower seal in place, wipe a little bit of grease on the lips of that seal too. Apply a very thin coat of form-a-gasket or an anerobic sealer or something like that on the cap next to the seal. Just above the pan gasket groove. Install the cap, torque to specs and install the oil pump, and pan. Use a dab of RTV at the corners where the gasket turns to go over the cap or timing cover. Do this on both the old style 4 piece gaskets AND the new one piece..
rearmainseal2.jpg


I've done lots of rear main seals over 15+ years of working for Chevy dealers and NEVER had to do the same one twice.

I hope this helps and I also hope I didn't confuse the issue for you. If you have any questions, just drop me a note..
 
It dosen't get any better than that explaination.....Nice!....I'm filing that one.
 
Any wonderful hints about changing out a 1 piece rear main seal easily?:eek:hnoes
 
The one piece seal leaves very few options. You have to pull the trans and flexplate/flywheel. The tool GM has to install the new seal is out there, but not too many people outside dealers have one. Put a thin coat of anerobic sealer around the outside diameter of the seal, lube the seal lips and press it in. Just make sure you don't fold the seal lips and it goes in straight. I find that packing the cavity on the inside of the seal helps.
 

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