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  •  » Oil leak help - rear main or oil pan?

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    10/01/2016 8:23 PM  #1

    DBROWN
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    Registered: 9/10/2013
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    Oil leak help - rear main or oil pan?

      I just reinstalled my motor after a complete rebuild. It is leaking oil at the rear of the engine. It is dripping right in the middle at the joint of the engine and tranny. The engine is a 302 mated to a c4 in a 66 mustang. The oil appears to be only on the engine side of the block plate. The block plate on the tranny  side appears to be dry. This led me to put a new oil pan gasket on. Still has leak. It is a Canton oil pan. I used a fel pro rear main seal and lubed it and the crank prior to install. Is there any way to tell if the leak is from the oil pan or the rear main seal? It is a one piece rear main seal on a roller block. 
      I did check to see if it was coming from up top. I know oil can be tricky.  I also have a breather on one valve cover and a pcv valve hooked up to manifold vacuum on the other valve cover. This was the way I had it before with no leaks.   

     

    10/01/2016 8:44 PM  #2

    MS
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    From: Canyon Lake, Texas
    Registered: 1/24/2013
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    Re: Oil leak help - rear main or oil pan?

    Sounds like rear main. Go to Wal Mart. Buy a can of jock itch spray. Clean the bottom of the engine thoroughly and spray a good coating of the white power on the area around the leak. Drive the car a few miles and get under it and see if there are any oil trails in the white powder.

    Another tip: the bolts holding the flywheel to the crankshaft go all the way through the flange into the inside of the engine where oil circulates. If no sealer is applied to the bolt threads, oil will seep past the threads and wind up on the flywheel. Usually this is in very small amounts showing up as oily streaks radiating from the center of the flywheel, rarely causing a drip type leak.  Put sealer on bolt threads, NOT the threads in the crank to avoid pushing sealer into the engine.

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
     

    10/02/2016 4:30 AM  #3

    Rudi
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    From: Stuck in the 50's Welland Ca
    Registered: 4/01/2013
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    Re: Oil leak help - rear main or oil pan?

    Thanks for the tip on the jock itch spray, I did not know Walmart carried it. Save me a trip to the doc for a perscription.

    Good work ain't cheap, Cheap work ain't good!   Simple Man
     

    10/02/2016 9:03 AM  #4

    DBROWN
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    Re: Oil leak help - rear main or oil pan?

    MS wrote:

    Sounds like rear main. Go to Wal Mart. Buy a can of jock itch spray. Clean the bottom of the engine thoroughly and spray a good coating of the white power on the area around the leak. Drive the car a few miles and get under it and see if there are any oil trails in the white powder.

    Another tip: the bolts holding the flywheel to the crankshaft go all the way through the flange into the inside of the engine where oil circulates. If no sealer is applied to the bolt threads, oil will seep past the threads and wind up on the flywheel. Usually this is in very small amounts showing up as oily streaks radiating from the center of the flywheel, rarely causing a drip type leak. Put sealer on bolt threads, NOT the threads in the crank to avoid pushing sealer into the engine.

     I did put sealer on the flexplate  bolts. It is all clean under there. I did not have a powdery spray but I did use hairspray quickly followed by talcum powder and it showed the leak right in the middle coming down the the block plate on the engine side. The oil pan butts right up against the block plate. The trans side of the block plate and the flexplate appear to be dry. 

       •Thread Starter
     

    10/02/2016 6:35 PM  #5

    MachTJ
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    From: Wisconsin
    Registered: 5/18/2014
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    Re: Oil leak help - rear main or oil pan?

    Without separating the trans and looking at the rear of the block there are three possibilities. 1 rear main. 2 cam core plug 3 oil galley plugs.

     

    10/02/2016 7:02 PM  #6

    jerseyjoe
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    Re: Oil leak help - rear main or oil pan?

    Is the PCV valve working properly or reversed..could be building up too much pressure in the crankcase.....jj

    Last edited by jerseyjoe (10/02/2016 7:06 PM)

    "Never put a question mark where God put a period "  Richard Petty
     

    10/03/2016 6:33 PM  #7

    DBROWN
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    Re: Oil leak help - rear main or oil pan?

    MachTJ wrote:

    Without separating the trans and looking at the rear of the block there are three possibilities. 1 rear main. 2 cam core plug 3 oil galley plugs.

     In process of taking out transmission. I don't think I checked to make sure the rear oil galley plugs were tight. If the machine shop removed them when they hot tanked it, maybe they were only hand tight. May get a look at that area tomorrow. 

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    10/03/2016 7:15 PM  #8

    50vert
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    From: QLD Australia
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    Re: Oil leak help - rear main or oil pan?

    Did you put rtv on the oil pan gasket corners??

    "Those telephone poles were like a picket fence"
     

    10/12/2016 6:43 PM  #9

    BobE
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    From: White Plains, NY
    Registered: 4/04/2013
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    Re: Oil leak help - rear main or oil pan?

    Sorry I'm late to the game, but try checking the rear of the intake manifold.  I had a leak on the back side of the passenger side that filled the little valleys behind the manifold and then ran down the rear of the engine between the block plate and the engine.  It's a little difficult to get your head back there to see if its leaking, try using a mirror.  Cleaned the area with alcohol and smeared some RTV and stopped the leak.

    65 Fastback, 351W, 5-speed, 4 wheel discs, 9" rear,  R&C Front End.
     

    10/13/2016 7:53 AM  #10

    DBROWN
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    Re: Oil leak help - rear main or oil pan?

    It was the rear main seal. Brand new fel-pro. Never had a problem with the previous ford racing one. The ford racing one only had 400 miles on it so I reused it and it is not leaking. I used all fel pro gaskets in my engine, but I think I will skip their rear main seal next time.

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    10/13/2016 2:29 PM  #11

    Grabber Blu
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    Registered: 10/13/2014
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    Re: Oil leak help - rear main or oil pan?

    Had  the same problem with a regular Fel pro  $12 rear main seal on a 351C,  Replaced with the $30 Fel pro and no leaks

    Larry

     

     

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