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karl1 10-12-2007 10:11 PM

rear main seal
i want to replace the 2 pc rear main seal in my 350 without removing the crank. how do i do this? what kind of seal works best? thanks

scholman 10-13-2007 12:01 AM


I have done this many times, back in the day.

Pull the pan off and take the oil pump off of the rear main cap. Watch out for the oil pump drive shaft. I put the pump in the pan for safe keeping.

Now take the two bolts out of the rear main cap and remove the cap. Taking the old seal out of the cap side is a snap, it is the engine side that gives people head-aches.

If the old seal is a rope seal then you will need to screw in a very thin and long eye bolt for wood. Then grab the eye bolt with a screwdriver through the eye and as you pull the seal have a friend rotate the crankshaft in the same direction. It may want to fight you but just remember it is just rope so you will win the battle.

If the seal is one of the new neoprene seals do the same steps but just look out for the metal in the seal and you will get this one out too.

Replace the old seal with the newer style neoprene style they are much easier to install than the rope. Be sure the lip faces toward the engine so it will not leak.

When I replace the main bearing cap I spray the mating surfaces with some 3M High Tac spray. Then re-torque the bolts to 65 pounds feet. Install the oil pump making sure the oil drive ligns up with the bottom of the distributor. Then tighten that bolt to 40 pounds feet of torque I think. Check these specs to be sure I am correct, it has been a long time you know.

Have Fun

artsman 10-13-2007 12:11 AM


Originally Posted by karl1
i want to replace the 2 pc rear main seal in my 350 without removing the crank. how do i do this? what kind of seal works best? thanks

You did say if the engine is in the car. If it is and the cross member is in the way of dropping the pan, you will need to remove the thru bolts from the motor mounts, the trans mount bolt and jack up the engine about 3-1/2 inches using a piece of 2X6 or other block of wood between the jack and pan, after raising the engine, put the thru bolts back in the mounts and it will hold the engine up.
You will probably need to remove the fan or shroud. Rotate the damper so the timing mark is at the bottom, this will allow the pan to clear the crank. Remove starter, pan bolts, oil pump and rear main cap. The top half of the seal can be removed by tapping the end of it with a soft punch and grabbing the other end with plyers. The new seal should come with a thin piece of plastic to insert part way into the top half of the seal recess so the new seal can slide past it to avoid damaging it on the sharp metal edge. There is a flat spot on the cap next to the seal that requires a thin amount of sealer. Oil the new seal and install it so the ends don't line up with the main cap split, about 1/4 inch should work. Don't know if one brand of seal is better than the other. I would recommend a Felpro one-piece pan gasket. You really should get a shop or repair manual of some kind that covers this job. Torque spec for the main cap is 70-85 ft lbs and 60-70 ft lbs for the oil pump.....Doug

DHMag 10-13-2007 12:22 AM

to avoid a leak, dont install the seal ends flush with the block/cap. an 1/8" offset is all you need.

Notorious 10-13-2007 06:14 AM

Not to worry, a 350 will not have a rope seal.

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