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do you have to pull the engine on a 50 Olds 303 to replace the rear main seal

Discussion in 'The Hokey Ass Message Board' started by cruzr, Jan 15, 2013.

  1. cruzr
    Joined: Jan 19, 2006
    Posts: 3,127

    cruzr
    Member

    ny help or advice would be appreciated. Recently bought a 50 olds , runs fine but leakes like a sieve
     
  2. Nope, use chinese fingers to snake the new seal though there. Plan on doing it more than once unless you just get lucky on the first try there is a slight learning curve.
     
  3. cruzr
    Joined: Jan 19, 2006
    Posts: 3,127

    cruzr
    Member

    is there a modern replacement seal available
     
  4. 53chevy
    Joined: Mar 5, 2001
    Posts: 1,570

    53chevy
    Member

    Try these guys:

    http://www.bopengineering.com/olds_v8.shtml

    I've used their one piece pan gasket (awesome) and bought their rear main seal, but haven't installed it yet, the rope seal I installed awhile back is OK. This was for my '60 Pontiac that is my daily driver. They use updated material.

    Ken
     

  5. Mr48chev
    Joined: Dec 28, 2007
    Posts: 33,861

    Mr48chev
    ALLIANCE MEMBER

    If you can lift the engine enough to pull the pan you can get by without pulling the engine. Usually guys lift the engine enough to slip wood blocks between the motor mount and the frame and and then drop the pan.

    Make sure that the distributor cap doesn't hit the firewall and make sure that the fan blades don't hit anything. You may have to pull one or both of them off to clear.

    I did a bit of a search and came up with this http://www.bopengineering.com/olds_v8.shtml Scroll down the page a ways and there is a rubber rear main seal listed for the 303.

    It looks like us AD truck guys can work a search.
     
  6. Thunderroad312
    Joined: Nov 18, 2012
    Posts: 158

    Thunderroad312
    Member

    A few thoughts on rear rope seals. First make really,really sure it is actually the rear main leaking. They tend to get blamed for oil leaks that come from alot of other places.Everything on the front and top of the motor will run back and down and collect near the back and drip off of the rear of the pan, making it look like it is the culprit. Second, everything in 1950 leaked, even when it was new. So be prepared that it will still leak when you are done, hopefully not as much though. First powerwash the engine top and bottom, and then run it and scrutinize things real well to make sure. If it is the rear main, the main reason (no pun intended)that they leak is worn main bearings, and excessive crankcase pressure. So with that being said also make sure the engine is mechanically sound before putting youself through the human hell of trying to fix the seal in the car. Also those cars are not that hard to r&r the engine and put it on a stand where you can work on it and actually see what you are doing.If I still haven't talked you out of doing this operation in chassis, here are some tips. After you have dropped the pan and removed the rear main cap, loosen all the other mains a few turns on the bolts and take the fan belt loose. This will allow the crank to drop down some. DO NOT waste your time trying to replace the top half of the rope, you will get the old one out, but even with the mystic majic chinese finger tool you can not sucessfully pull the round rope into a square cut groove all the way around and not tear it. With the crank hanging down take a piece of thin (1/16) welding rod, and sharpen one end of it to a point. Now curl it to a shape slightly larger than the O.D. of the seal groove in the block. Gently tap the piece of welding rod between the seal and groove in the block. Once it is in, trim it flush with the parting line. Now replace the lower half as you would normally, by packing it into the seal groove in the rear main cap and trimming it flush. Reinstall the rear cap and tighten the others to specs clean everything real well and install the pan with new gaskets. The rod behind the seal tightens the top half with out having to remove it. Also consider trying a neoprene replacement, If you do that then obviously you would replace both halves. If you stick with the rope, make sure you get a good one. The originals were made with asbestos, and since our government feels it needs to protect us from ouselves, they took the asbestos out,and some of those were pure junk. I believe Best gasket makes a graphite impregnated rope which works pretty well. Good luck, I hope this helps you avoid some pitfalls.
     
  7. F&J
    Joined: Apr 5, 2007
    Posts: 13,222

    F&J
    Member

    a rope can be pulled on the block side without even loosening the front four crank main caps. I have done it, countless thousands of others have done it.

    There is another place these leak, near the rope seal; at both sides of the rear main cap, there are two rectangular blocks of cork. These get loose after decades, and leak. They should be in the kit for a true replacement rope rear main kit for Olds. I found a NOS kit locally.
     
  8. GOATROPER02
    Joined: Mar 22, 2006
    Posts: 2,059

    GOATROPER02
    Member
    from OHIO

    And not all rope is created equal as far as material. i have 2pc seals on the shelf....ph and Ill walk you through it.

    Tony
     
  9. i always hookup my remote starter button so i can bump the engine over as i pull the rope around the crank.
    a tip; remove the pan, put a drip pan or cardboard under motor, come back the next day to do the work.
     
  10. Fairlane Mike
    Joined: Sep 21, 2010
    Posts: 389

    Fairlane Mike
    Member

    Be V-E-R-Y careful if you bump the engine, it works, but just check everything, especially if you have the engine jacked up, you can tear up a lot in the process. I would say if you can get the rubber seal, use it, a lot less trauma!!
     
  11. George/Maine
    Joined: Jan 6, 2011
    Posts: 949

    George/Maine
    Member

    I had a 49 olds and it could be leaking from the vally gasket under the intake,and make sure the valve cover gaskets and not leaking and draining.De muck and clean the pan and oil screan,and new pan gasket.
     
  12. mr50s
    Joined: Jul 26, 2009
    Posts: 59

    mr50s
    Member

    Hey All,

    Good advice here from the posts listed above, including some I hadn't thought of. Just wanted to second the advice from George/Maine about cleaning up the muck while your engine is down. I did this type of clean-up with a well-used 1950 Olds 303 which was both leaking on the ground and smoking out the breather.

    When I got the car fired up and on the road again, I found that the oil pressure gauge now registered normally, and that the oil drips and breather smoke had all but disappeared.

    mr50s
     
  13. Marty Strode
    Joined: Apr 28, 2011
    Posts: 8,801

    Marty Strode
    Member

    As I remember, you don't have to jack up the engine, but you need to drop the steering, to pull the pan. With the bottom half of the bell housing removed, it should make it more accessible. Go with Goatroper's advice, he is serious about Olds engines!
     

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