Installing a rope seal

So, I've got this big ol' Cadilliac with a leaky rear main seal. I put the existing one in myself several years back, but apparently I did it wrong. The one I put in was a two-piece of modern manufacture. From what I understand, this engine originally came with a rope seal.

So, learn me. Easy to install? Tough to install? Tips and tricks?

I have nothing helpful to offer, but when they show this on TV shows, they don't use the rope seal, they use a modern replacement. I know that makes you feel much better.

The only thing I noticed on a show the other day rebuilding a Buick, they substituted two piece rubber seals and they staggered the joints a little (clocked a few degrees off level).

http://www.vintagevehicle.co.uk/fitting_rope_seals_is_a_bit_of_a.htm

Interesting write up for a jag xk - maybe similar for the caddy in the process...noting that even pretty new brit cars were known for their leaks, er, um...chassis self-lube systems. Edit - fwiw, I'm changing the TR4s scroll (pretty much a rope seal) to a viton seal

In reply to spitfirebill: It's a shame that 1.98 part takes so much time to change or can ruin a perfectly running motor.

The only way to put a rope seal in properly involves the crank out, and a wooden dowel. I had, and maybe still have, a "Chinese finger trap" thingy that would pull a rope seal through the slot with the crank in place, but I never had the courage to try it- I figure the term "packing" is a better description, and I don't see how you can pack it if the crank is in the way. About half the time, on old V8 Yankee stuff, the "rear seal leak" is actually the pan gasket, or a seep past the parting line between the block and the rear main cap. I always add a very thin skim of anaerobic sealer to the surface of the main cap when I install one.

I have a rope seal thingie used on a 1963 Buick Special 215 V8.

If this works for your application, pay the shipping and it's yours.

Dan

Streetwiseguy wrote: About half the time, on old V8 Yankee stuff, the "rear seal leak" is actually the pan gasket, or a seep past the parting line between the block and the rear main cap. I always add a very thin skim of anaerobic sealer to the surface of the main cap when I install one.

Now that's an interesting tidbit. I shall examine more closely.

Keith, not a lot of vendors for caddy stuff. Probably pretty easy to get under and Dx the leak? hahahahaha.

I know the Ford FE motors use a rope main seal. You might check the FE board.

Also, the H.A.M.B forum probably has some good tips.

Good luck.

If it's like the rope seal in my Bonneville, the original seals had asbestos in them; the problem is the new ones don't, so they don't seal as well.

How I've done it is to put the seal in place in the groove (with the crank removed, of course) and then roll a big socket back and forth on the bearing surface to push the seal into place. Then, carefully trim the excess off each end with a new razor blade, and put a dab of RTV on each end before bolting down the bearing cap.

I was thinking I've seen a Viton replacement rear seal for older Cadillacs...check with the Cadillac performance websites, maybe you'll find something.

You need a Sneaky Pete. The Lisle tool number is 27000. You remove the oil pan, then remove the rear main cap. The screw thingy screws into the end of the original rope seal so you can pull it out. The Chinese finger thingy goes on the end of the new seal so you can pull it through. From experience, it's easier if you loosen all the main cap bolts so the crank will drop down maybe 1/8" or so. Also, do not cut the seal off too short. It's better to pack some extra in there before cutting it off. Rope seals should be easy to find.

Two piece rubber rear main seal: http://www.caddydaddy.com/1963-1964-1965-1966-1967-Cadillac-Rear-Main-Seal-Free-Shipping-In-the-USA-p2877.html

I did one like that in a small block Ford with the aforementioned 'loosen the main caps and lower the crank' method. I was worried about the torque converter seal, no problems though.

EDIT: I see you already replaced the seal once with the newer type. It didn't get put in backwards, did it? It's easy to do!

I am not going to deny that possibility.

I hate changing rope seals.

As a faithful Pontiac owner, I've learned all the tricks.

The sneaky pete is a good tool, problem is, the seal you put in will likely be as bad or worse than the old one.

The Pontiac factory service bulletin detailed the following fix. I've done it a few times now and it works better than the other methods.

1) Pull the pan and remove the rear main cap only.

2) take a soft brass drift and bump the ends of the seal that remains in the block back up into the block about 3/16 of an inch. This will swell the seal in the block and make it seal tight again.

3) Remove the old seal from the cap and roll in the new seal. When you trim it, use a fresh razor blade and cut the seal about1/4" over long on each side. Use a fresh blade for each cut to make it nice and neat.

4) apply some RTV to each of the cut ends and the parting line. feed the ends into the spaces in the block and torque the cap down.

5) reassembly is reverse of disassembly.

After saying all the above, there are a few thing to check for:

Pull the torque convertor cover and get in there with a flashlight. The plug in the rear cam journal likes to leak after a number of years. It may be that, not the main seal.

If you are thinking of using a two-piece neoprene seal (if one is available) you might need to have the knurling removed from the seal groove in the crank to get it to seal properly. The knurling is there to pump oil away from the rope seal but it may cause a neoprene seal to leak. You need to remove the crank for machining though.

Last, a little drip now and then is normal, these seals need a bit of oil in them to work properly.

Good luck with your fix.

Shawn