Blown engine

Discussion in 'Norton Commando Classic Motorcycles' started by Adam_R, May 12, 2018.

  1. Dances with Shrapnel

    Dances with Shrapnel VIP MEMBER

    Joined:
    Jul 8, 2011
    You say "if it does get rebuilt". I say get a large bottle of Blue Heron Vodka, a large jar of Queen Olives stuffed with either blue cheese or garlic, and then sit back and begin to "think like a fish"!
     
    JimC likes this.
  2. JimC

    JimC

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    Oct 12, 2007

    That’s funny! +1 on the garlic stuffed olives.
     
  3. Fast Eddie

    Fast Eddie VIP MEMBER

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    Oct 4, 2013
    You guys have piqued my paranoia again!

    Must get the nice looking gauge kit that Constant sells that I nearly bought last year!
     
  4. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009
    [​IMG]
    What if some of them are stuffed and some of them aren’t?
     
    Nater_Potater likes this.
  5. grandpaul

    grandpaul VIP MEMBER

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    Jan 15, 2008
    "Left turn, Clyde..."
     
  6. 850commando

    850commando

    Joined:
    Nov 1, 2014
    right turn Clyde!
     
  7. RoadScholar

    RoadScholar VIP MEMBER

    Joined:
    Dec 28, 2008
    New pumps are expensive, but I replace them at each major re-build. As DynoDave said: People that can look at a pump and tell if it OK are magic, or something to that effect. When you consider the abrasive "material" that is in the oil, from blow-by alone, never mind the primordial soup of sub-micron metal bits, it is a wonder to me that the pumps live as long as they do. The articles I have read talk about axial clearance between the cast pump body, the gears and the cover plate; you can, certainly, return that to OE specs, but you can't restore the fit between the gear teeth or the radial clearance between the gears and the pump body without easily exceeding the cost of a new pump. An oil pressure gauge or a pressure warning light is your friend.

    I don't trust oil pumps with unknown history, and I don't trust 44 to 50 year old connecting rods. When you consider the time and money it costs to do a quality re-build a new oil pump is small potatoes. Granted, a new pump won't make up for excessive clearance, but if you measured all your critical clearances after tear down and clean up, you'd know where your problem areas are. I also highly recommend measuring the same critical areas prior to re-assembly; rebuilding an engine is a fun and learning experience, rebuilding the same engine twice (in a short time) is personal stupidity; you should see my dunce cap, seems like I have to learn everything the hard way...Hope you don't
     
  8. Bernhard

    Bernhard

    Joined:
    Apr 20, 2011
    Re; “An oil pressure gauge or a pressure warning light is your friend.”

    Notwithstanding the truth in that comment, an oil pressure gauge will show a normal pressure but will not inform the rider if the centrifugal oil strainer in the crankshaft is blocked up!!!
     
  9. Bernhard

    Bernhard

    Joined:
    Apr 20, 2011
    Re; “the oil tank was removed and cleaned out as well as the pipes.”

    Very good, but and I stress, but, that was then this is now, let me explain, I had a jap two stroke twin with a separate oil tank that fed the engine via a pump, one fine day it started seizing , I pulled into a garage and got some two stroke oil and fed it into the petrol tank so I could get home. After arriving home I looked at the oil tank pipe and saw that no oil was coming out, further investigation revealed that some dude had poured some fine grit into the oil tank. It looks like I had some fine neighbours who took a dislike to anything on two wheels as I was not apparently the only biker who suffered in the hands of these creeps. So. . . .don’t assume anything.
     
  10. grandpaul

    grandpaul VIP MEMBER

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    Jan 15, 2008
    I found a cup of sugar in my Kawasaki 125 gas tank once....
     
  11. oldmikew

    oldmikew

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    Jul 25, 2015
    It would surely show higher pressure
     
  12. Fast Eddie

    Fast Eddie VIP MEMBER

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    Oct 4, 2013
    Won’t show any more than the OPRV spring is set to though will it?
     
  13. oldmikew

    oldmikew

    Joined:
    Jul 25, 2015
    on start up no, but it would still show up after a few mins running with higher than usual readings, maybe not long enough to save a crank journal ,but what about your life? surviving major blow ups is luck not judgement.
     
    Last edited: May 18, 2018
  14. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009
    Gradually, so you wouldn't notice.
     
    JimC likes this.
  15. oldmikew

    oldmikew

    Joined:
    Jul 25, 2015
    well it depends on the obstruction and how sensitive the rider is to oil pressure data.
     
  16. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009
    That sounds right to me, but...

    It takes tens of thousands of miles and (in many cases) decades to get from an empty trap to a full one. Better keep a diary.

    The possible increased pressure effect may be countered by wear and varying oil viscosity.

    If you have a good oil pump and bearings, pressure will aready be as high as it will get.
     
  17. oldmikew

    oldmikew

    Joined:
    Jul 25, 2015

    A good indication might be when starting a warm engine and you get higher than expected pressure. Not saying it will double- but it will be higher. And the rise time of the pressure gauge itself will be different. On start up oil is flung straight to the drive side journal and then back to the timing side . If the trap is blocked the time will be halved.
     
  18. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009
    I'm highly dubious.

    I hope never to find out for sure.
     
  19. Fast Eddie

    Fast Eddie VIP MEMBER

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    Oct 4, 2013
    I’m dubious too. There are one or two guys on here who are really ‘in tune’ enough to respond as you suggest oldmike. But I think the vast majority of the rest us would continue to see high pressure as ‘good’ until something went tight, or bang, or both!
     
    Kvinnhering likes this.
  20. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009
    And the people who know their engines that well do not have full sludge traps.
     
    Yakatak and Fast Eddie like this.

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