VCCA Home Forums TECHNICAL - 1945 AND NEWER 1946-1948 Rear Main Seal!!!!!!!!!!!!!!!!!!!

So I had made a post about doing the oil pan gasket and rear main seal. I go the pan off and found that the gasket was very brittle and there was oil on both sides of the gasket, so i know that was leaking. My questions are.....

1) How can I tell if the rear main is leaking?

2) Should I bother to replace the rear main seal while I have oil pan off or should I just let it be.....?

Anyone have any advice?

Thanks for helping this young car guy out!!

If the rear main seal was leaking oil would be dripping from the little hole in the bottom of the flywheel cover after the car had been driven for a distacne (other "problems" could have caused a leak at this point also). The rear of the main bearing cap would look wet at the lower center area and the front of the flywheel may be "well oiled". When removing the rear main bearing cap and inspecting the seal the rope seal material should not have oil on it in the area the seal contacts the crankshaft. This area should look dry.
Years ago the standard practice was to replace just the lower half of the seal and remove shims if required to get the bearing clearence down to about .001". Replacing the top half of the seal is difficult and seldom helps. Packing the ends of the top seal into the grove and adding pieces of the old lower seal to fill-in can help.
When replacing the pan gasket it MUST be done in this manner.
The side gaskets are "stuck" up onto the block first. I use a stiff grease to hold them in place.. Then the end corks are placed into the groves of the front and rear main bearing caps. Pre bend the corks fitst by taping them to a soda or beer can for a few days. The ends of the seals must but up against the little tabs on the ends of the side gaskets. A smalll drop of gasket sealer can be dabbed on the area where the end cork meets the side gasket. I use 4 studs (heads sawed of from 1/4" bolts) and thread them into the pan bolt holes This helps to guide the pan straight up and keeps the gaskets from slipping. Flll the connecting rod oil troughs with oil just before putting the pan up in place, -----also check the oil pipes in the troughs with the gearden hose to make sure all pipes are open.

TY thats alot of info and help. the flywheel dosent look "well oiled" but the car has been sitting for bout 6 months. There is no inspection cover over the flywheel so I can not tell if it is leaking, is this something u think i should just do or am i tempting fate by messing with it?

Thanks Again

You may be tempting fate at tis time.

Ok, I think I am gonna pass at this time at least I have the parts and the knowledge now if I need to replace!

THANK YOU VERY MUCH CHEV NUT

Ho Boy, I have '31 & a '49 I may have to drop the pans on so will put this in my favorites. Thanks from me also.

The pan gaskets for my spare '31 & '49's should be here tomorrow. Do you soak the end corks in anything before you tape them to the pop can to form ?

Jerry,
Jagermeister should work just fine. Just enough to make sure that the cork is moistened. Might mix a little water to make sure.

Thanks, will try it.

The question no one has asked and will determine if you need a rear seal or not is the operation of the clutch. A bad rear seal will contaminate the clutch ruining the throwout bearing and pressure plate.

Are you experiencing any abnormal clutch problems? When you let out the clutch does it engage the flywheel in a smooth non jerking movement? You can hear and feel a bad clutch? If you put on a new gasket for the oil pan and have a bad clutch caused by contamination you can always go back and redo the clutch, real seal, and again replace the pan gasket. You might be able to salvage the new pan gasket so nothing is lost if you do as Gene says. We have had a lot of discussion on the 37-42 chat site on this issue within the last month. You ought to review some of it including a picture I took of my contaminated 48 clutch parts.

You also need to get a replacement for the flywheel cover. Let me know if you need one. You should not be driving your car without one. Send me a PM for details. Good luck, Mike

P.S. There is also a great post on replacing oil pan gaskets on this site above this post. Reading it carefully will insure you don't end up with a leaky pan gasket. Six months is probably too long to correctly gauge whether you have a bad rear seal or not. Most oil residue will have dripped off by now so you won't see drops of oil ready to fall off of the throwout bearing or clutch parts. If by chance you do see a drop forming on the transmission side of the flywheel you are in for a new seal and maybe even some transmission and clutch work. I am just finishing doing a new complete wheel seal replacement, a replacement of my front bearing in my transmission and a new pressure plate and throwout bearing. I have a 41 sedan with a 48 engine in it.

Soaking the end corks will not help because they are made from liquid resistant material.

Thanks. Gaskets came today.
One more question until this week-end. I stripped one of my locking nuts on the connecting rod on the '31. Can't round one up around here so is it OK just to put on another regular nut and lock it that way? Going to check one more junk yard tomorrow.

I have extra lock nuts from a 42 216 engine. Do you want me to send you 2? Mike

P.S. If you took a nut and cut it in half or thirds would that work?

Thanks for the offer Mike but I'm putting the pan on tomorrow. I'll try cutting one in half and if that doesn't work I'll just use a '31 bolt, nut and cotter key. I think the bolts should be the same. If not, I'll just drill a hole in the bolt that's on there and use a '31 nut and cotter key. That's after I check 2 more places tomorrow for the right lock nut.
Hey, just saw your the Featured Chat Guy. Congrats!!!