Rear main seal question

[jimbob78cj]

The rear main seal on my 304 is leaking badly. I am wondering whether I can replace the rear main seal without pulling the crank? If so are there any special tricks I can use to pull the cap and fish/push/whatever the block half of the seal around the crank main journal? I have got a 360 to eventually replace it as the 304 is pretty worn and don't want to put a whole lot of time/effort/money in the 304.


Thanks,

-jim


"Jeeps don't leak, they just mark their territory."

[JERSEJO]

Yes! Absolutely the seal is a 2 piece seal. Drop the pan, remove the rear main cap and the lower seal is housed in it. The upper seal can be pushed out after you loosen the remaining main caps to get some of the tension off the upper seal. Don't back the remaining main cap bolts off too much. You just want the crank to drop a small amount. When installing the upper seal half make sure it is pointing the right way, compare the seal lip to the lower seal ( which can only be installed the correct way). Carefully push the upper seal in. The most inportant part of this job, and the part that will result in a leak if not doen properly is the application of sealer to the lower seal and main cap. FOLLOW THE INSTRUCTIONS THAT COME WITH THE SEAL.

Do not forget to retorque the remaining main cap bolts.

[jimbob78cj]

Loosening all the caps means that the tranny, clutch and flywheel are going to have to come off too right? If that's the case, then I'm leaning toward putting more effort on getting the 360 going and installed sooner.

[tufcj]

I've done it without loosening the mains. Remove the rear main cap. Use a SMALL punch to move the seal to one side. Once it's protruding, grab it with a pair of pliers and have a helper turn the crank to walk it out. You can use a socket on the harmonic bolt, removing the plugs helps.

To get it back in, soak it in oil. Just use your fingers to walk it in while a friend turns the crank. The lip faces the front of the motor, be sure to get it facing the right direction. Add a TINY dab of black or gray RTV to the cap right around the bolt before tightening it down to help it seal.

If you're working under the truck, stick the pan gasket to the block with some weatherstrip adhesive. You don't need to coat the gasket, just enough to stick it to the block. Add a dab of the same RTV where the end gaskets meet the side gaskets. You never want to coat cork gaskets with RTV.

Bob
tufcj

[JERSEJO]

No just back off the mains a couple of turns. it is much easier to install the upper seal half with some extra space. I don't doubt that Bob has done it without removing the pressure off the main caps but it is a lot easier and not a lot of extra time. it is much easier to damage the new seal by not doing it the way I explained.