I am swapping out a bad 3.4 motor on a 95 Camaro with a used one I got from a junk yard. I am planning to change the water pump, thermostat, trans seal. Is it difficult to change the rear main seal? My old engine was leaking like a siv there and I'd rather change it before I put the new one in. Any advice would be appreciated! Thanks, Sid

 

http://www.autozone.com/autozone/par...7252_166719_0_

if you have an old used engine that you are going to install, why not at least put in a new gasket set in addition to the seals?

 

^^ I second that, regasket and seal the whole motor. It cant hurt. Just remember to get new head bolts since they are torque-to-yield.

Massey

 

And re-do the timing cover gasket too!

 

It's a pain to change that seal. I think there's a special tool to do it that makes it easier. The seal is big and has a thin metal shell. It's easy to distort it. Take a close look at the seal area and if everything looks dry I'd leave well enough alone. But that's just me, having had bad experience with those seals.
Look also at the triangular seal at the back of the camshaft. That leaks and it is very easy to fix.
Here's a shot of the back of the used engine I bought to put in my 94. While the cranks seal looks good the cam seal is a mess. And the back of the intake manifold was improperly sealed by someone who worked on the engine. They replaced the RH cylinder head and weren't very good.
This engine turned out to be junk, having water in two cylinders. I ended up rebuilding the original engine from my car.

 

Thanks for the info! I will leave that seal alone, then. I am changing the seal above the rear main seal that you mentioned. My old motor leaked there also, so I figured I should change it while I have the replacement motor out. I'm also changing the water pump, as I've read the Camaros have problems with blocked lines if not flushed regularly. And I found some of the lines 1/2 blocked and the line where the thermostat goes is really blocked.
Sid

 

Buying/installing a used engine is usually a crap shoot. Most of the time I've had very good luck but once or twice I've been hosed. I try to buy only engines I've heard run but that can be tough and once backfired on me. It was Ford Focus engine out of a wreck with front end damage and a ruined radiator. The engine started and ran fine so I bought it. Upon installing it it had a terrible dead miss. Turns out that two head bolts were rusted and snapped off in the block and the head gasket was blown. The engine ran fine in the donor car because the cooling system was dry! Doh, I didn't think of that at the time. Live and learn.
So when you buy a used engine you have to decide how much time and money you want to put into it before you see how it performs.
On the one hand it'll never be easier to change all the gaskets and seals while the engine is out. But then you may find that you bought a turd and you just spent a couple hundred on gaskets, seals, coolant pump, etc. Bummer.
On the other hand you can install a used engine that turns out to be a real winner, performance-wise, but it's a leaker. Or it takes a coolant pump in 2 months and now you're bending over a fender to replace it.
With the used 3.4 I got hosed on, I didn't hear it run but the low miles seduced me. Mistake. The seller lied, which I discovered after pulling the VIN from the block and running CarFax on it. I decided to pull the heads to install new gaskets because I did *not* want to do that in the car. Two cylinders had bad corrosion damage and the motor was junk. At least I didn't discover that after installing it.

As for the leaking cam bore gasket, I strongly recommend Permatex "Brush-Tack" adhesive and *not* any silicone sealer. The Brush-Tack is really sticky (like contact cement) and won't allow gasket squish out. Just about all the silicone sealers Ive used were too slippery and didn't seal very well. The exceptions were Manufacturer-branded small tubes that were very expensive. You get what you pay for. Usually.