1. Old Mike

    Old Mike Active Member

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    I was looking at past threads here and probably didn’t go back far enough, so I don’t know if this has come up before. Has anyone changed the rear main seal on a 383 without disassembling the whole engine?
     
  2. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    First bit of advice I have is to check the oil pressure sender. They leak, oil runs down around the bell housing and mimics the rear seal leaking.

    But, yes, they can be changed in the car.
     
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  3. 1978 NYB

    1978 NYB Warfighter FCBO Gold Member

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    I've had a few oil pressure sending units leak and lost a lot of oil dripping down the bell housing.
     
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  4. traintech55

    traintech55 Senior Member FCBO Gold Member

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    And please do not forget the ever present Valve covers. One trick I used to use is clean the engine with Brake clean real good, let it dry completely, then spray some foot talcing powder over the back of the engine. It will show up like an arrow.
     
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  5. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    Wow! Learned something today! Thank you!
     
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  6. traintech55

    traintech55 Senior Member FCBO Gold Member

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    Your Welcome.
     
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  7. 65Fury440

    65Fury440 Senior Member FCBO Gold Member

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    Wow, that is a great idea!! Thanks!!
     
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  8. furious70

    furious70 Active Member

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    In my current 383 in the fury I managed to roll a new rope type seal in without taking everything apart.
     
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  9. Welder guy

    Welder guy Old Man with a Hat FCBO Gold Member

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    Did you manage to change your seal with out removing the transmission? Tell me more .
     
  10. 68PK21 440.6bbl

    68PK21 440.6bbl Senior Member

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    On the old cars with a 2 piece seal you don't have take the transmission out.
    It's all done with removing the oil pan (don't forget to rotate the crank) and taking the rear cap off.
     
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  11. furious70

    furious70 Active Member

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    Did not pull the trans. Had my a500 in there at that point
     
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  12. furious70

    furious70 Active Member

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    Yup
    And I can't say it's leak free but it replaced a seal that was leaking visually a couple drops per minute
     
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  13. Welder guy

    Welder guy Old Man with a Hat FCBO Gold Member

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    6561B2EF-950E-471A-A30D-6A45C60577CD.jpeg Thanks for the info, my rear main seal has been leaking For a couple years now and it’s gotten very bad. I had it up on my car hoist to verify the leak. I bought the seal a while back thinking it’s a winter job. It won’t wait. Hers a pic of the new seal I’m going to use.
     
  14. furious70

    furious70 Active Member

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    Fyi my uncles advised me that a rope type may be easier to roll in
     
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  15. 68PK21 440.6bbl

    68PK21 440.6bbl Senior Member

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    Boy that's old stock, 02/19/03 date.

    Yea those are the newer 2 piece rubber/silicone types, you may still have a rope seal, if you do have a old harden rope one there are some tricks to get it out. Just read the install directions on the new one carefully and don't be shy with the grease in the curve of the seal, just avoid the ends as you want the RTV to make a good seal. I've had that type go in easy but some I've had to loosen all the main cap bolts to let the crank drop just a bit to get it to slide in (truck application). The bitch of the job is dropping the Y-Pipe if you have a single exhaust and your flange nuts and bolts are rusted tight. Burn Baby Burn, just torch them off and put new ones in.

    Let us know what was in there that you remove, the way I remember the rope seals went, white asbestos? rope OEM (soak in engine oil for 24hr before install) to black graphite rope, and now the 2 piece rubber/neoprene/silicone type.
     
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  16. Welder guy

    Welder guy Old Man with a Hat FCBO Gold Member

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    584F7914-C5A5-48E3-80BE-9488C6186FF7.jpeg Ya it’s old stock but still made in the USA as far as I can tell.
     
  17. Welder guy

    Welder guy Old Man with a Hat FCBO Gold Member

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    Hey I’m totally sorry for hijacking this thread. I’m learning a few things and I have to replace the seal on my 383 as well.
     
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  18. Old Mike

    Old Mike Active Member

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    I wasn’t thinking of doing it with the engine in the car. I thought I’d pull it and put replace the oil pan and valve cover gaskets and clean up the k member. But thanks for the info. I’ll be sure to check the pressure sending unit.
     
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  19. Welder guy

    Welder guy Old Man with a Hat FCBO Gold Member

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    F3819035-49E8-4073-8B47-3C1049D81D7C.jpeg 33D22525-AFF9-45DB-9AF5-636E131FDB5A.jpeg 65601DE6-7A98-4771-894F-E4CAB6B3AD9D.jpeg 95DBE690-965E-4EFA-BCCD-4BC137400A7E.jpeg 2749F643-B042-4773-AC25-94A67A972A22.jpeg A8609DAB-DA65-4534-9360-43719C83483C.jpeg My seal has been replaced at least twice In its life the last time was in 1998 when it was rebuilt. A few years back i bought the Fel-Pro rear seal kit and noticed it had a few extra parts in the package. Then thinking I may need other seals and gaskets down the road I bought the whole kit at a swap meet. Ya I know - my name is welder guy and I have a buying problem. Here’s a few pics. I’m not sure what the Small black tubes or the L shaped parts are for , they are not included with the mopar seal. Thanks again for the information!
     
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  20. 68PK21 440.6bbl

    68PK21 440.6bbl Senior Member

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    heh Oh boy, I'm getting myself involved in a whole can of worms here with I take it a RB engine? 383? 440? or whatever takes that type of cap.

    Well Well Well, some information that I have just gleaned off the net with the rubber seals in a 440 are:

    "There exists a manufacturing defect in many BB castings, in that the groove that holds the Rear Main Seal in the Block, is "offset", or rather, NOT CONCENTRIC with the Crankshaft Centerline(mains)."

    Makes you wonder why the OEM used a 'Rope Seal' (packing type).

    "I will never install a rubber rear main seal again ..."

    "How hard is it to install block side of rope seal with engine in car?
    I am one rubber rear main seal #3 (tried all style rear caps)so I am ready to try a rope seal.This is on a 67 440 and it does have the knurl."

    Those extra's are FelPro's way/idea? to make sure it's a leak free endeavor.
    Again read the instructions and look at pictures/diagrams (if any).

    Most of what I read about the tricks in installing the rubber seals were during a engine rebuild when the engine was out of the car on a stand. Thrust bearing wear, the concentric offset as noted above, knurled vs. smooth crank wipe surface... on and on.
    Again there is a reason why the rope seals were used.

    One important thing to remember to do is get yourself a good (preferably machinist) straight edge and check your oil pan for bolt pull in the oil pan bolt area.
    If you do have the bolt pull (most old oil pans do) make yourself a apparatus to put in your vice to 'Tap' the rise back to flat. (common problem for leaks)

    BTW Back in the day I've used the rope seals with all the old Mopars before the new 2 piece seal came on the market with no problems. BUT! The engines then were a lot newer and original and most likely... well lets just say as they left the factory!

    I have done 1 & 2 piece rubber seals mostly in Fords with no problems so...

    <ahem> Good Luck!
     
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