rear main seal replacement 73 Dart 318 V8

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Lasalle

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Anybody out there done this before? It doesn't seem too hard according to the shop manual. No need to lift engine. Drop the pan. Remove rear main cap. Original seal will be rope. New replacement seals are split rubber. Removing old and installing new seal above the crankshaft seems tricky. Is it? Book says to rotate the crankshaft during removal and installation. Should this be done with starter or a socket on the front? Is there a difference in brands for new seals? Best place to get new seal?
 
Any auto parts store can get a seal. NAPA might have a better quality seal. I usually use Oreilly or Auto Zone. Mostly Chinese stuff.
 
Done it many times, remove rear main and loosen the rest so the crank can drop down a little.
Tap the old seal in with a small punch until you can grab it on the other side and pull it out.
You can usually push the new one in by hand all or almost all the way. Help it in with the punch if not. Lube it up with oil.
Be careful to keep the seal tight to the crank as you rotate it in or the block will cut a slice off the outside edge of the seal.
 
When dropping the oil pan, the shop manual says to remove the bolts holding the exhaust pipe to the exhaust manifold so the exhaust pipe can drop down. Is this necessary to make enough clearance to drop the pan? I am hesitant to try to remove 50 year old bolts on an exhaust manifold.
 
Don't worry, so what if you snap the bolts at least it ain't like breaking a stud. Just drop new bolts in.
Probably have to get a Dremel in there and cut them anyway.
 
Lasalle said:
When dropping the oil pan, the shop manual says to remove the bolts holding the exhaust pipe to the exhaust manifold so the exhaust pipe can drop down. Is this necessary to make enough clearance to drop the pan? I am hesitant to try to remove 50 year old bolts on an exhaust manifold.
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Soak those puppies with pretty much any penetrate over several days, then a little heat. I'll bet the nuts come right off.
 
You may have to raise the motor to get the oil pan out I did. Lift at the pan then slide some 2x4x6" wood blocks in between the engine brackets then lower back down, make sure the 2x4's don't block dropping the pan. While you're at it separate the oil pickup and clean the screen, you may find pieces of valve stem umbrellas.

This worked for me without loosening the journal caps. If you cant pull it out you can try and push it out with 3 or 4 12" zip ties, they make a good chaser for small pieces too.

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Threaded a screw into the old rope seal to get a better grip.
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Lasalle said:
When you say "loosen the rest" do you mean the front main bearing cap only or all the bearing caps on the connecting rods?
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Not the rods, just the mains.
It probably only let's the crank drop a few thousandths but it helps.
4.0 Jeep engines have the same style seal, and I did HUNDREDS...
 
The leak turned out to be coming from the oil pressure sending unit not the rear main seal. Several sources (including this forum and youtube videos) said to check that before changing the rear main seal. I checked it today while the car was running and it was leaking a lot. Thank you to all who offered advice.
 
I'm glad you found the real problem, and that it was an easier fix. While we are on the subject, I haven't had much luck stopping oil leaks by replacing just the rear main seal. It has been my experience that there is usually a bit of a groove worn into the crank by the seal itself. Just replacing the seal might not totally fix the problem. Some oil still seems to seep past the new seal and the groove. I have been told that oversize seals were available for just this problem, but I have never been able to find them.
 
UPDATE even though the oil pressure sensor was leaking, it was not the only leak because I continued to get spots on the ground under the bell housing. (it was oil not transmission fluid). So, using advice from this thread and youtube videos, I changed the rear main seal and the pan gasket recently. Thank you to all who responded. It was a big job but I did not have difficulty removing the old rope seal. BUT I'm still getting spots on the ground in the same place. The back of the engine is oily. Next step is valve cover gaskets? What about where the distributor mount? Can that leak?
 
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Lasalle said:
Thanks for the reply. That is a real possibility. That is why I'm going to wait to try anything else.
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Hope that's it. Mine was doing the same after replacing the rear main. Pulled the inspection plate and hit it with brake cleaner and airhose. Did the trick. Of course, came to find that my 90 oil filter was weeping too...lol. Good luck with the troubleshooting.
 
I am cautiously optimistic the leak is fixed. There were no drips on the ground after the last two times I have driven it. Looks like Divenut was right.
 
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