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360 rear seal experts wanted!!!!

westirmax

Contributing Member
Sirs:

After much research and debate and finally the cost factor. I was planning on re powering with indmar 5.7's, My mechanic and several other "chrysler guys"- talked me into replacing the rear seal in place of the re-power.

My situation is a 28 rampage express with twin counter rotating 360's, which run strong and cool. My only issue is the port motor( standard rotation) leaks oil from the rear seal. not enough to be a lubrication issue but enough to make the bilge a mess and generally tweek my already tweeked OCD.

My mechanic has done this type of thing before( but not for a few years), My slip mate who has 360's has done it a few times as well, so between the two I think we have enough experience to get it done.

My questions to the experts is:

1-chance of success in stopping the leak?
2-rope or rubber?
3-what if anything else should I do when we drop the pan? ( oil pump?)
4-who makes the best parts and where? ( felpro,mopar performance?)

Ideally I want this to last at least 2 seasons before I can get the re-power done.

any and all input will be appreciated!

Greg-
 
1) Chances of stopping the leak are excellent provided it is done properly.
2) Most automotive are going with the rubber these days. They both require some finesse.
3) Your pulling the engine in two years, my feeling is if it works don't fix it.
4) Felpro seems preferred. See the link. They also stagger the seal halves in the block and cap to keep away from their mating edges.

http://www.forabodiesonly.com/mopar/showthread.php?t=316433&highlight=rear+main+seal

Krazykuda is a top small block builder on that site.

If a rope seal is in there currently then you likely have slinger serrations on the crank. Looks like a lot of slashes....\\\\\\\\\\\\\..... around the journal. Should you decide to use a rubber seal as opposed to the rope, the serrations should be polished smooth to help prevent seal failure.
 
Got ya on all of the above with the exception of #3, I cant take the oily bilge anymore...call it OCD but its ugly and not very good for the environment and just bad practice...plus just keeping the engine diapers functioning is a PITA...
I read the posted link and seems like if started with rope i should use rope. I guarantee its never been touched so its like 25 years in position and its just now leaking. so old school doesn't mean its a bad system and polishing the hash marks doesn't thrill me.

in ref to #4- you mean the seems where the halfs meet is hidden in the middle of the journal and the middle of the cap? all the data ive seen have the seem between the journal and the cap?

Whats the opinion about running the engine outside the boat to test the seal. Some data says if it doesn't leak in the first 15 minutes its all good...
 
I was referencing the oil pump if it works don't fix it or if don't need it don't do it. Just a cost factor. Is it delivering good steady oil pressure?

If you decide to go to rubber from rope, some polish to the serrations is recommended. You don't want the serrations to eat you seal. If there is already a rubber seal in there you should be OK.

#4 - End of the cap seal sticks out approximately .250". Same on block. You are staggering the parting lines when assembled. You can't do that with a rope seal.

If you have the means to run the engine before installing, go for it. I don't know that I'd put a time limit on a test for a leak and call it conclusive.

There is a remote possibility the rear cam plug has developed a leak.
 
Last edited:
Dave:

got ya on the oil pump yes its doing its thing as it should no reason to change.
Were 95% sure its going to be a rubber seal since this is the "standard rotation engine" circa 1989. It we open her up and find rope we have them ready as well. I will have a new pan gasket and sealant ready. new oil and a new filter, gonna change the plugs and wires while the motor is "up in the air". freshen the paint and treat any rust we find....Hey if this cures the issue I'll run these engines into the ground. For the longest time i though to re-power but these engines start easy run all day and are a good match for the boat. I'm not changing engines till I have too. fingers crossed we nail this issue....

Greg-

P.s.- gonna paint and dress the engine bay when shes out too. some things you cant reach with the engine in..
 
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