Changing rear main seal - who can assist or help ?
 

Hi guys, I need to renew the rear main seal of my FE390. Is anyone out there who can assist or help ? Is there maybe a tutorial how to do ? Whats the best way to do it ? Best regards from germany, Stephan

1. check the back of the intake and heads to be sure that any leak on the bottom of the engine is not actually coming from there and not the rear seal.
2. remove oil pan - all bolts. when removing pan, i use a wide flat screwdriver which i gently hit into the gasket all around. this slowly wedges the pan off. you should not lever with the screwdriver so you dont mess up the sealing surface.
3. can be done with the engine in the car. original style frames will have a crossmember just below but in front of the rear main cap
4. remove the rear main cap bolts. need to pull the cap loose. it is a tight fit and this is not easy, especially in the car. I used long threaded rods into the oil pan bolt holes and pulled it down and also back and forth. you could use a sliding hammer if not under the car (no room if under the car on jackstands) i put a metal plate across the 2 long threaded rods and levered that plate against the frame crossmember and even the block plate with a long bar. getting the cap off is hard to do. it took me several hours over a couple of days. just keep working it
5. the bottom half of the rear main comes off easily, usually with the cap. the top of the rear seal may be able to be just pushed out around the crank. if it has been in there a long time, might be difficult. there are special curved tools that can help. do NOT scratch the crankshaft in any way.
6. install the new top half of the rear seal. make sure the ends of the seal are clocked slightly so the seam between the top and bottom of the seal is not aligned with the seam of the main cap - the rear seal should be slightly off to decrease the chance for a leak. i put a tiny drop of silicone sealer on the ends of the seal but most don't. i think i put the bottom half of the seal in the cap and then installed the rear cap.
7. reinstall the cap. i used a bit of silicone sealer on the top ends of the cap. getting the sides to seal is a bit of an art - whether using the rubber seals and nails or just a thick bead of silicone or The Right Stuff sealer. there are a few vdeos on youtube that show this. torque the bolts correctly. i was told not to use the rubber side seals at all, but i think if I had to do it again, i might just really coat them in silicone and slide them in, then the nails.
8. i also put some sealer on the inside seams of the cap, deep inside the block behind the crankshaft, but I dont think these are helpful
9. clean off the oil pan surfaces and install with new gasket. i like to put a bit of sealer where the seams are on the front and back (the seams of the rear cap and I think there are similar seams in front)

I would add if you are using the nails with the side seals make sure they are flush or slightly recessed. Sometimes they need a little shortening.

JKG gave you a pretty good rundown on the procedure but I have never had to fight getting the rear main cap loose. Definitely check for the leak elsewhere because they all (valve covers, intake manifold, distributor, oil filter adaptor, etc.) drip off the back of the motor. Good luck!!

John

FE motors, being a 1950's design leak some oil. Most leak a lot of oil. If you're going for a leak free FE, it's going to be a frustrating experience for you. Just sayin'.

+1 on checking the back of your heads and intake manifold. I got an old 352 4V in my replica, it just poured out oil on my garage floor. After replacing three rear main seals with no improvement, I checked the back of the heads and intake manifold and found oil all the way across, I cleaned up the surface and placed some silicone and to my surprise I only see a few drops under the car.

You may well have a bad seal. Another possible consideration, do you have excess/severe pressure in the engine putting undue force on whatever seals you have in place.

My engine is not an FE, but a 460, yet the same dynamic may apply. When I bought my car it was leaking notably at the rear seal. I had the inspecting mechanic replace the rear seal. It really had no effect, it continued to leak considerably all over the garage, etc.

I did my own research, and added a PCV valve system on the engine, which was not in place when I bought the car. From that day forward, never a drop from the real seal.

The PCV valve also significantly improved the operating characteristics of the induction/engine. It starts better, idles much smoother/better, and the crackling/popping/backfiring upon deceleration that I was experiencing, stopped.

Seemed like a little miracle drug! The improvements that system touted were impressive, and it didn't disappoint. I can only assume soemone removed it thinking it was emission control device that was bad thing for a performance car, maybe? At any rate, seems to have been what resolved the leaking issue on mine.

Brent