Topic: 51 ford 8BA engine rear seal

PeterFord    -- 07-05-2011 @ 3:21 PM
  I have ordered a new rear seal for my engine. It is the "packing" type. Can that seal be installed by just removing the oil pan?

Many thanks. Peter

supereal    -- 07-06-2011 @ 11:02 AM
  The top half of the rear packing is held in place by a retainer, and the flywheel has to be removed to replace it. I've never done it with the engine in place, so perhaps someone else has. We do it as we reassemble the engine on the stand. You remove the retainer and the old seal, then install the new packing. Clean the retainer slot in the block, and apply a coating of sealer, such as Perematex #2. When in place, be sure the retainer and the oil seal are flush with the block. Seat the lower half of the packing in the pan, and apply a dab of sealer on the ends. If the packing is correct, no trimming should be necessary. You don't have to soak the rear packing in oil before installation, but if you plan to do the front seals, be sure to soak the halves in oil overnight. There is a dust seal on the lower half of the flywheel cover that you may wish to replace, too. Removing the flywheel means taking out the transmission, the clutch, etc, so you may elect to only replace the bottom half, if the leak isn't large. I'd replace both halves of the front seal, as it can be done by removing the timing gear cover. Just be sure to observe the position of the distributor so it can be replaced correcly. Before you reinstall the pan, check the mounting holes and hammer flat any that are distorted. This is a cause of oil leakage around the pan from overtighening the mounting bolts. They should be tightened in sequence from the center to the ends at 15 to 18 foot pounds only.

51f1    -- 07-06-2011 @ 3:02 PM
  I recommend removing the crankshaft to replace the rear seal. I'm sure someone in the Flathead days devised a method to replace it without removing the crankshaft. They used a Chinese handcuff type thingy to pull the seal through. I don't know where one would get the tool today.

I've seen information that the seal should not be shortened but that it should be left to protrude past the block-pan mating surfaces. The factory manual does not address this. Anybody have any information on this? That's the way I installed my front and rear seals on my 8RT. The front doesn't leak and the rear doesn't leak much. The factory manual calls for soaking the rear seal in oil for 2-hours.

Why wasn't a neoprene seal developed to replace the rope seal? Even my '49 Crosley, the sorriest American car ever built, had a replacement neoprene seal. It had to be cut to install it around the crankshaft.


This message was edited by 51f1 on 7-7-11 @ 12:03 PM

shogun1940    -- 07-06-2011 @ 7:18 PM
  we used to replace rope seals with a chinese finger tool from lyle tools, the secret was to lube the seal and to turn the crank while pulling the seal through. leaving an 1/8 of an inch on either end. I never did a flathead this way i will have to go out and take one apart to see.

supereal    -- 07-07-2011 @ 12:51 PM
  There also used to a tool sold to replace main bearings without pulling the crank. It fit in the oil hole if you had the bearing cap off, and pushed the insert out as the crankshaft turned. If they worked at all, they usually damaged the insert, anyway. The reason the rope seals are not trimmed is so they are forced into the groove completely, then they swell a bit to add tension. We always put a dab of sealer on the ends "just in case". Some repro seals are sold too long, so buy them from a reputable vendor. There are Teflon rope seals on the market, but as far as I know, they are not better than the usual kind. If the rear seal is badly leaking, I'd pull the engine and do the job right, and consider replacing the pot metal retainers, as well. All rope seals leak a bit, in any case.

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