1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Zero oil pressure to head

Discussion in 'Norton Commando Motorcycles (Classic)' started by murraycod0, Dec 28, 2013.

  1. murraycod0

    murraycod0 VIP MEMBER

    Joined:
    Nov 24, 2009
    Hi all,
    just finished putting my new project together and fired it up and have no oil pressure to the head.I have a MK 3 timing cover on a '74 engine.I changed the oil pressure valve .Just hoping it was that.No . Then I took the cover off and checked the seal, spring & piston and they were all in place.While the cover was off I put a new large gear oil pump on as the engine is all rebuilt I don't want to damage it.The oil is returning to the tank ok. The engine sounds great for the short time I have run it.The last one I built there were no problems with the same setup.The oilways are all clear and I have a gauge set up off the cover.With the new pump it still just spits oil out but will not build up pressure??????????
     
  2. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    The Mk3 timing cover will have an extra hole in it. It is in the passage between the relief side of pressure regulator and the gasket surface. That passage lines up with a hole in the engine case that goes to the passage leading to the inlet side of the pump.

    To use the Mk3 cover you must screw a setscrew in the hole in the case that lines up with the passage. If that passage is not blocked then the pump will draw air through the extra hole and the engine will get very little oil. If you need more assistance with this I can take pictures tomorrow. Jim
     
  3. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    Sorry, Jim, but that information isn't correct.

    The 850 MkIII timing cover is the one that does not have the OPRV return drilling at the gasket face, and as far as I'm aware, there's no need to blank off the oil gallery in a pre-MkIII crankcase in order to use a MkIII timing cover as the MkIII timing side crankcase still has that gallery open at the gasket face even though it is not actually used.

    850 MkIII cover:
    breather-valve-problem-t7562-15.html#p79006
     
  4. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    Did you fit the MkIII type 06-6190 pump seal?
    http://www.ebay.ie/itm/NORTON-COMMANDO- ... 33781a5610
    [​IMG]

    If I remember correctly, the MkIII seal support washer (between the pump and seal) is also different.
     
  5. Rohan

    Rohan

    Joined:
    Aug 26, 2010
    As well as previous, disconnect the oil feed to the head, and see if it will build oil pressure just in the bottom end. ?
    Should be OK if not done for long.
     
  6. jaydee75

    jaydee75

    Joined:
    Jul 2, 2012
    I'd try a gauge on the feed lines themselves. I'm not sure you get any pressure on the cover.
    Jaydee
     
  7. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    A gauge should normally show full oil pressure when connected to the timing cover outlet.
     
  8. murraycod0

    murraycod0 VIP MEMBER

    Joined:
    Nov 24, 2009
    I have the correct washer on the pump and a gauge hooked up down at the cover.The seal in the cover is the right way round on the crank.I will need to take off the cover again and see what I can find .
     
  9. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    Some timing covers have the hole drilled and others do not. I have both here. If the hole is drilled and the relief hole is in the passage then a plug must be used in the case. The cover that was on my MK3 when I got it has both holes drilled. Jim
     
  10. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    I've never seen or heard of such on a MkIII timing cover (what would be the point)?



    You don't mention anything about that here? : breather-valve-problem-t7562-15.html#p79006

    My MkIII cover certainly hasn't got the joint face hole.
     
  11. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    Good question. But I assure you some do. Then there is a plug in the matching hole in the case. Jim
     
  12. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    Yes, but, even if the second hole was there, if the gallery is drilled the same as the pre-MkIII timing cover then the oil would still have to blow from the OPRV to reach it, so there would be no pressure loss (to the crank and valve gear) and no need for a blanking plug in the case. The oil from the OPRV would simply be recirculated back to the pump inlet same as the pre-MkIII arrangement.
     
  13. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    Here is a mk3 cover with both holes.

    [​IMG]

    If both holes are left open then the suction side of the pump will be connected to an open hole in the timing chest. That will cause the engine to wet sup immediately and the oil pump will draw air from the open hole. I believe I have seen this mentioned in the INOA list tech also.
     
  14. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    OK, never seen a MkIII cover like that :shock: [Edit] However from murraycod0's description the oil is circulating normally, and no immediate wet sumping problem mentioned so far.

    I do see what you mean about a back bleed problem from the oil supply if both blow hole galleries are connected. I think I'd want to blank off the "second" hole in the case if it were mine, or find another MkIII cover. Hopefully, murraycod0 will be able to tell us if his MkIII cover has this extra hole or not?
     
  15. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    My bike originally had a slotted head screw in the case. I removed it and put a ball bearing in the hole in the cover so the oil bypass would be directed to the intake of the pump as on the 74 model. I can't say it made any real difference. The oil pump doesn't produce enough pressure to overcome the pressure relief valve once the engine is hot anyway.

    Norton supposedly made the change to avoid heating the oil by running it through the pump over and over. Jim
     
  16. murraycod0

    murraycod0 VIP MEMBER

    Joined:
    Nov 24, 2009
    Hi I have my cover off again and it does not have the hole like Jims .I am priming the crank to make sure it has some lube and putting the gauge on the cover .Will try to prime it there to bleed it free of air back shortly.
     
  17. murraycod0

    murraycod0 VIP MEMBER

    Joined:
    Nov 24, 2009
    Checked the oil pressure valve , shimmed it . Took the srm one off,put an original type on, removed the anti wetsump spring and piston.Measured the seal measured the end of the shaft interference and protrusions all ok.Seal on pump is pushing on cover alright .Light her up and still no pressure.Ugghh!
     
  18. concours

    concours VIP MEMBER

    Joined:
    Dec 29, 2011
    Have you checked for FLOW to the head? banjo off, oil squirts out of feed line from timing chest? Could be a Foreign object blockage. How is you gage rigged? On the opposite end from the feed? Rocker spindles all oriented properly? You verified the gage with shop air?
     
  19. ML

    ML

    Joined:
    Jul 30, 2007
    Murray,
    I'm not sure if you have done this, but ignore the pressure gauge for the time being. Is there oil returning to the tank? It will be intermittent squirts at low pressure. If so that means the feed side is pumping into the motor. Next, disconnect the rocker feed pipe and see how much oil is actually getting pumped, as that is part of the feed. If that is stream of oil, not just a dribble, then the feed is working OK. I would then suspect your pressure gauge is faulty. If that gauge is proven to be OK, I would then remove and strip the pump and examine the gears and end face clearance.
     
  20. concours

    concours VIP MEMBER

    Joined:
    Dec 29, 2011
    Show us a picture of the gage setup off the cover please.
     

Share This Page