Crankshaft rear oil seal leak

[Guest]

Hi <P>After rebuildng my 50 Caddy's 331 engine I have found that the rope seal for the rear main bearing is leaking. This is the 3rd old engine I have rebuilt( Austin Mini and Ford Consul before) and this is the 3rd to leak. Each shop manual tells a different story when it comes to installing the rope seal. <P>To cure the leak is it possible to remove only the rear bearing cap and replace the rope seal with a ne slightly longer one or is the only solution to remove the gear box and drop the crank 1/2 inch?<P>As some manuals say to cut the rope flush, other say leave 1/8 inch at one or both ends is there a way to ensure an oil tight seal????<P>Regards<BR>CrestaMan

[Guest]

Those rope seals are the agony of all backyard mechanics. While probably best replaced with the engine out- you can try to drop the crank slightly and pull the new one around the crank. They sell a crude 'chinese finger' tool to help install the new one. I would leave 1/8 inch 'proud' to combat the inevitable shrinkage. And that might be the root of the problem- cars that sit idle for months will have their seals shrink. If the leak is not gushing you might try one of the 'stop leak' products sold to stop oil leaks. These are typically petroleum products that promote swelling of the seals. Sadly, these engines were made before the automotive industry changed the rear seals to a neopreme rubber. Good luck.

[Guest]

I reciently replaced the rope rear main seal in my 62 olds.Iused one of those chinease finger jobers.I didn't drop the crank,if you turn the crank while you pull on the cable of the inserter you can get the seal around the crank, cut the seal about 1/8 longer on both ends and pack the excess in with a aluminum punch,{will not nick the crank}making sure that none of the seal would get pinched between the cap and the block.Soak<BR> the seals in motor oil for a day before attempting to install it in the engine..I then crouded as much of the bottom seal into the cap as I could and tamped it to shape with a slug of steel the same size as the rear main bearing,Then cut it flush with the mating surface.Don't forget to replace the cork side seals.<BR>

[novaman]

Are you sure that is the rear main seal and not the side gaskets? I'm not familar with this engine but it sounds like what some Big block Mopars motors would do. Also, with your bearing cap off, inspect that area of the crank and make sure that it doesn't have a groove wore in it from the previous seal. I agree with the others about leaving extra seal, so that when you tight the cap it crushes the upper seal into the space and forms a tight seal as well as taking up for some shrinkage. You may also want to silcone along your side seals for some extra protection there.

[The Old Guy]

I have had some success with leaky rear seals by pulling the rear cap ,driving one or two pieces of wire between the block and seal ,putting some hemp rope between the seal and cap ,and reinstalling the cap .This might sound unorthodox ,but it pushes the seal in closer contact with the crank ,and seems to work.

[Guest]

Crestaman,<P> I've seen only one of these threads mention soaking the new rope. This is a must, and the longer the better. Definitely, leave it longer and pack it up in. Don't get in a hurry trying to install it. Sometimes they go easy, sometimes not. If you get in a hurry, it will get very frustrating. As a side note, some of the old seals were soaked in hot oil to help absorption. You won't need to do this. Take your time.<BR> I've even used thin mechanics wire, looped it around the end of the rope and fished that through. You must make sure the wire won't catch on a surface and scratch it. <BR> Make sure the extra you leave on the ends doesn't get packed flush. A small amount needs to crush to seal.<BR><p>[This message has been edited by Alan Terek (edited 04-13-2001).]

[Coley]

hey, progress is not complete on the Buick line ...my wifes 86 Buick w/V6 had a main leak. I pulled the cap and what did I find??? The good ole rope seal...WHAT engineer got paid to do THAT!!

[Guest]

Thanks for all your views and idears guys...<P>As soon as it stops raining here in England I am going to try pulling the cap, compact the top seal with a soft punch and replace the cap bearing seal with enough excess either side to fill the cap.<P>I will let you know how I get on in May when the Great British Summer is supposed to arrive ;-)