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Wet Sumping, Oil Pressure Relief Valve and AMR Modification

Discussion in 'Norton Commando Motorcycles (Classic)' started by PeterJoe, Apr 9, 2015.

  1. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    Re: Wet Sumping, Oil Pressure Relief Valve and AMR Modificat

    Although the MkIII cover should reduce the rate of drainage through the pump, it won't prevent oil from seeping along the pump shaft bores from the feed to the scavenge where it can drain straight down to the sump. This is the reason for the pump shaft O-ring modification.
     
  2. pete.v

    pete.v

    Joined:
    Oct 31, 2009
    Re: Wet Sumping, Oil Pressure Relief Valve and AMR Modificat

    Yes, mine does too. As stated, it does help, but not perfect. My pump is reworked and massaged. It is what it is.

    Even if it still seeps by, the cam chain inspection hole is still worth it.
     
  3. PeterJoe

    PeterJoe

    Joined:
    Dec 8, 2011
    Re: Wet Sumping, Oil Pressure Relief Valve and AMR Modificat

    If you are not happy with the rate your motorcycle is wet sumping it is possible to isolate where the leaks are happening. First you can remove the rocker feed line and just observe how much oil comes out of the oil passageway. If the oil just keeps running out after a period of time then it is safe to assume that your anti wet sump valve is not seating properly. Of course if the oil stops draining there then the anti wet sumping valve is ok. With the Mark III timing cover the oil pressure relief valve has nothing to do with wet sumping.

    Unfortunately the 1972 Norton does not have a sump screen which would have been handy by removing and visually checking whether the oil is back flowing through the scavange pump pickup.

    Now you can remove the timing cover, plug the oil pump outlet, plug the threaded hole in the engine case and disconnect the oil return hose that goes to the oil filter. Clean the pump and the area all around really well. Over a period of time visually inspect to see where the oil is leaking externally. If it is leaking at the brass end plate seam, resurfacing the plate and the pump body should really help. If it continually leaks out through the oil pump's input shaft that would indicate there is an internal leakage of the pump from the delivery side to the scavange side. This is what the AMR o-ring modification corrects. Also if there is a leak around the area where the oil pump is mounted on the engine case it could mean that the gasket is shot or the mounting nuts/studs are loose. When I took my bike apart the mounting nuts were barely snug and the studs were loose in the engine case.

    These are ways of methodically isolating the cause of rapid wet sumping on your engine. I hope this is of some help.

    Peter Joe
     
  4. swooshdave

    swooshdave

    Joined:
    Apr 15, 2009
    Re: Wet Sumping, Oil Pressure Relief Valve and AMR modificat

    Is an o-ring the best solution for this application? Wouldn't an actual oil seal be better?

    [​IMG]
     
  5. bill

    bill

    Joined:
    Jun 1, 2003
    Re: Wet Sumping, Oil Pressure Relief Valve and AMR modificat

    yes IMHO a seal IS the proper way to seal a rotating shaft vs an O ring but it will work for a while. an O ring is more apt to be used on a stationary app or where two parts slide across each other like a short travel piston is pushed in and out in a bore (think automatic transmission's). also the MKIII timing cover has a habit of the piston sticking in the open position so just give it more clearance in the bore.

     
  6. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    Re: Wet Sumping, Oil Pressure Relief Valve and AMR modificat

    Only if you wanted it to last.
    Unfortunately not much room to work with. Jim
     

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