350 chevy rear seal

I have a 350 s/b chevy motor, the rear seal is leaking. Is it possible to change the seal without tearing the engine completely apart? I had the engine in my A it ran fine just leaked. I am in the process of building a 27 T coupe and plan on installing this motor in the T. I built a new motor for the A. I am just trying to save some money. Machine work is expensive. What is the best way.............PINCHER Thanks

 

You need to know what year the block is. I think its like up to 87 had a 2 peice seal which is an easy fix. But if its a 1 peice then its pretty much a tear down. Hope this helps.

 

thru 86 was two piece, 87 up was one piece, although a few engines switched earlier. Crate (Hecho en Mexico) engines used the two piece a lot longer.

You can change both in the car, usually. Two piece you need to pull the pan. To do the one piece you need to pull the trans or the engine, pry out the seal, and put in a new one with a special tool. you can do it without the tool if you pull the pan and seal adapter too.

t

 

Up to 1985 SBC V8 was two-piece. Some GM crates are still built with this.
1986-up SBC is one-piece.
One-piece is easy to tap in carefully with the trans. out of the way IME.

I'll take a less-leaking 86-up rear main seal, factory roller cam 87-up, longer wearing cylinder walls, drilled for either starter pattern late model block over an old one every time.

 

The easy way to tell is that if the crank has a flange on it it's a two piece and if the back end is round with no flange it's a one piece. It's almost impossible to confuse the two as the one piece seal has to slip over the end of the crank.

To change the two piece seal you obviously have to remove the pan and then take the rear main cap off and loosen the other main caps to let the crank drop a little so you can get the top half of the seal out. Make sure that you put the new one back in with the lips facing in.

Torque all of the main bolts and put the pan back on with a new gasket. Felpro makes a one piece gasket that seems to work pretty well.
While I had the pan off and the main bolts loose I'd take a look at a couple of the bearings and if they looked suspect i'd change them out as the aren't all that expensive. Same for the rod bearings.

 

You do not need to loosen the rear mains to replace a 2-piece seal, do some searching , w/a simple tool , you just roll out the old & in , the new!!
dave

 

Thank's to all who responded to this. The motor is out pan is off. it is a 2 piece seal. I think the engine is 80/ 84 Dip stick is on passenger side of car. I am going to give it a whirl. Thanks again..........PINCHER