I have a '78 Ford 302 that was rebuilt 120,000 miles ago.
The rear main seal is leaking about a quart a week. I've heard that the rear main seal can be replaced on some of these 302's without pulling the motor. Is this right and if so tell me more about it.. The truck runs great other wise. Thanks,

Bob

 

[updated:LAST EDITED ON 25-Nov-02 AT 11:17 PM (EST)]Yea, you can do it. Pull the bottom nuts off each motor mount, pull the fan shroud and disconnect the cooler lines if you have an automatic. Jack up the truck enough to crawl under it to work, and put GOOD jackstands under the frame rails! I mean no offense, but if it falls on ya, you may not be around anymore! Put the truck in neutral and emergency brake on hard. Jack the engine up enough to put at least 2" wooden blocks between the mounts and frame, and lower the engine onto them.. Pull all the pan bolts and lower the pan to the crossmember. Before moving the pan out, disconnect the oil pickup tube and let it fall in the pan. Now the pan should come out with a little maneuvering. You may have to move the crank a bit to clear all the counter weights. Clean out the pan well, and the pickup tube screen. Engine degreaser works good here, so does gasoline but be carefull. Now remove the rear main bearing cap. Set it aside. Loosen all the remaining main caps so the crank drops down about 1/32" (no more!) This gets the crank pressure off the upper part of the seal. Okay, if you have a rubber seal you can use a blunt instrument to push the upper part around the crank and out, or sometimes you can get a grip on it with needle nose pliers and pull it out. Whatever you do, DON'T scratch the main journal on the crank. If you have the original rope seal, you can run a sheet metal screw into it and pull on that. Again, watch that journal.

When the old seal is out of the top, pull the seal half out of the cap. If it was the rope seal, you'll see a little pin in the center of the cap. Tap it out as you won't need it with the new rubber seal. Work a new half of the seal up into the upper slot leaving about 3/8ths of it extending from one end of the slot. The rubber blade of the seal should be pointing in towards the rest of the engine. I don't use any sealer in these things but if you want to just put a little on the back of the seal (not the blade side). Now put the other half in the cap also extending 3/8" beyond-on the OPPOSITE side from the block half. The idea here is to get the mating ends of the seal halfs IN the metal and not even with the split of the cap and block. This helps keep that joint from leaking. Put the cap back on. Soak the side seals in oil and put them on without any sealer. Tighten the caps back up to torque. Put the new pan gasket and seals on the block using a quick setting sealer (sometimes I use little dabs of superglue if things are clean). Put the pan back on in reverse; place the pan on the crossmember and while it's under the engine bolt the pickup tube back on. This can be a bitch if there's not much room. Once on, raise the engine a tad, pull the wood blocks, and lower the engine SLOWLY so you can shove it around if the mount studs don't want to line up correctly. Tighten the mounts, put on the shroud, and connect the cooler lines. Fire it up and run it up to normal temp. Check for leaks. These are the basics for changing the rear seal in-truck for the 302 and other small blocks circa '73-'79. Should work for ya! Polkat