I have a 52 flathead that I having trouble stopping a leak at the rear main seal, the engine is just rebuilt and I am hoping it is not an issue with the crank surface. I have changed the rope seal 3 times and still have a leak. Any suggestions on installation procedure as obviously I am doing something wrong.
Yep, replace the rope it with the newer two piece molded rubber style; I would think it must be available with a like looking, and you can slide it (lubed) in with the crank in the truck by just lossening the crank bolts.
__________________ 1951 f1 460 / C6 / MII
“Old, cynical, and cranky.”
Last edited by Old F1; 08-04-2010 at 10:04 AM.
Reason: sorry for typo / spelling, to early for me!
Sounds like a challenge to get it in with it in the truck.
Only if you make it one.
I was looking for a two piece on eBay (search), didn’t see one for a flaty, newer ones.
But this came up some kind of new rope type? I know nothing about this!
1949-1951 V8 308 c.i., 337 c.i. Flathead
This rear main seal has been upgraded to a higher quality style of rope rear main seal. This new style of rope (Graphite Rope Teflon Coated (PTFE) Rear Main Seal) is highly conformable to the crankshaft and housing cavities, will hold up to high temperatures, and does not need to be pre-soaked in oil. Sealing performance is superior to both NOS asbestos ropes and their non-asbestos substitutes. Kits include two lengths of rope packing, side seals (if used), an installation instruction sheet, and a special knife for trimming.
I still think the two piece is avilable somewhere.
Every FelPro kit I've bought comes with both that "new" graphite and a white teflon-impregnated rope seal that is even "newer".
How bad is it leaking? You can't expect it to be totally leak free, that just isn't the way rope seals work.
Usually when a new seal leaks badly, it was cut short (not enough rope in the groove). It is really hard to get it deep enough into the groove without something like the official tool; a round piece of steel about the same diameter as the crank.
I bought a gasket kit and I think it has both types of seals. I wasn't sure which ones to use.I guess the black ones are the way to go although the appear to be a bit flatter than the white ones. Do I have the right ones? I'll try to take a picture of them and post it.
The other question is, since I have the engine out and on a rotating stand, should I remove the crankshaft and replace both at the same time?
I am just concerned about getting it and the rods torqued properly.
I have been procrastinating about this for a while and would like to get the truck running again. I don't mind a small oil leak,it's a work truck for the yard and not really anywhere else.
Best Gasket's graphite rear seal is supposed to be the hot stuff. I used it on my rebuild and it's leaking... not bad, but it drips.
I don't know of any one-piece lip seal that works on the rear of a flatmotor. Replacing the part of the rope seal with the engine together (crank installed) isn't likely to be successful. It doesn't just "slip in there", it needs to be rolled in with a lot of force, then cut. Possible to nick the crank trimming it and make things worse.
I just did an oil pan front and rear rope seal from best gasket. The material was graphite and it just popped right in. No effort was needed. I left 1/2 of an inch on both sides just in case the crank pushed it further in the grove. Trimmed there material gasket on all four points it met the rope seal than used a couple dabs of rtv on these trimmed places to insure that the different materials sealed correctly. Hope this helps I did not change top seals just bottoms no leaks. This was a flat head 226.
The Best Gasket seals were highly recommended to me, so I had them used when my engine was rebuilt. They leaked like a sieve. The machinist who installed them does plenty of these engines, so I don't know what the issue could have been. But when I had to pull it apart again, I used the FelPro, and it's tight as they get. I do like the Best kit because of the "popsicle stick" they give you to trim it. I used it on the FelPro, too.
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