Thread: Rear Main Seal

Tweet

Have a 1968 Chevy C-10 Pick-up 327-400 auto Tranmission. It,s leaking oil into the dust cover pan. So I belive the rear main seal is leaking. My question is, Is there a good way to replace the seal without takeing motor out of truck? Thanks, John.

You need to remove the oil pan. I'd check valve covers, Rear intake,Oil sender and distributor gasket first!!

It might only be your rear pan seal; new pan gasket set will cure that.
If it is the main seal, you need to drop the pan, remove the rear main cap, push the top half of the seal (the part in the block) out with a punch - a brass punch is better than a steel one, and be real careful not to bugger the seal channel - until you can get hold of it with a pair of pliers and pull it the rest of the way out. There are several different ways to get a new upper half in place: 1)Find a "seal puller" ( I prefer this) - a braided wire sleeve, sort of like those old "chinese finger handcuff" toys;
2)Loosen all of the other main bearing caps a little bit and let the crank drop a little, and carefullypush the new seal half into the groove, then re-torque the crank. This is chancier, because of the possibility of messing up other bearings, or the timing chain.
There may be some newer techniques, but these are the only ones I have used, and this is with the "rope" style seal.

Instead of removing the upper half of the rope seal you can tap the two ends in about 1/8 inch then using a new piece of seal cut
two 1/4 inch pieces press carefully into place,trim with a sharp blade. Install new lower piece and your go to go!
This is how I was taught by Chevrolet. Don't pack to tight! seal the bearing cap and properly torque!

The rear pan gasket. Did not think about it. Now I did this. I took off the dust cover which was filled with oil. I crank up engine and layed up under truck with a flaslight and wacth the spot at back of motor where seal is while engine was running. I could see no leak. But I did not look at pan at all. Really don,t know if I can see it. At that time, I felt like the main seal was not leaking. But when I drove truck to work today. After work I looked up under truck and seen a big spot of oil. checking further, I seen it was driping from the little hole in the dust cover. That when I detrunon it was indeed the rear main seal. If you drive the truck 50 miles you could loose about 1/4 to 1/2 qut of oil I drive about 80 miles a day so I,m loosing about 2/3 to 1 qut. a day. Thanks, John.