Blown engine

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

  1. Adam_R

    Adam_R

    Joined:
    Nov 20, 2015
    Was out on the 850 for a run last Sunday, slowed down for a bad corner and started to accelerate up the hill, clatter clatter! Pulled in the clutch and ground to a halt.
    looked down to see oil and a mangled shell. instantly knew the worst :(
    spent the next 2 hours looking all over for parts.

    Got brought home by the RAC and stripped the head and barrels off.
    Crank looks toast, piston on that side is knackered, obviously a hole in the casing,
    bore has a groove in it.
    The rod end has snapped in half but the bolts are ok if a little bent.
    I'll let the pictures do the talking







    I had initially come to the conclusion of oil starvation , but am not so sure as there was oil on the ground and was still dripping when i moved the bike to the side of the road.

    Any Ideas?
    The engine was rebuilt less than 1000 miles ago, all new bearings etc

    as for what to do next, i've no idea
     
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  2. Kvinnhering

    Kvinnhering VIP MEMBER

    Joined:
    Feb 16, 2011
    Sorry for the blown engine. Thats bad!

    Do you have some valves (anti wet sump) in your oil line?
     
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  3. Adam_R

    Adam_R

    Joined:
    Nov 20, 2015
    Its got a manual valve that was most definitely open. we have had this off to make sure that it was opening correctly
     
  4. Kvinnhering

    Kvinnhering VIP MEMBER

    Joined:
    Feb 16, 2011
    OK. Then I will take off the cover on timing side and inspect seals to crank and oil pump. Also check gear to the oil pump.
    I belive you have plenty oil in your tank and you clean slug trap in the middel off crank during the rebuilt?
     
  5. kommando

    kommando

    Joined:
    May 7, 2005
    That's the shell bearing material smeared on the big end journal so looks like oil starvation. What does the other big end look like.
     
  6. Dances with Shrapnel

    Dances with Shrapnel VIP MEMBER

    Joined:
    Jul 8, 2011
    New rods, pistons. Hopefully the crank will clean up with an undergrind but make sure they get the filet radius right or we will be seeing another photo essay like this one in a few months. May want to take crank to an Aeromotive place to conduct a Magnaflux (crack test) of the crank for cheap insurance.

    What Kvinnhering says about root cause. Check condition of crank feed end lip seal, Pressure Relief valve function and cleanliness, oil pump installation, gasket condition etc and feed lines. Also check that the rubber donut and shimming seal between the oil pump and outer timing case cover is correct for the model of Commando. There may very well have been some improper rebuild involved here.

    I would bin the anti drain valve - just my not so humble opinion. Check for unobstructed flow from the oil tank to the feed side of the motor (maybe someone left a shop rag in the tank). If it's not too late, try and get a figurative snap shot of where the tank oil level was at the time of failure (empty, full etc.)
     
  7. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    Sorry to see that mate, especially after only just having rebuilt the engine.

    Looks like oil starvation to me too.

    Meaning oil starvation at the big end journal. Just cos there’s loads of oil on the ground doesn’t mean there was adequate oil pressure at the journal.

    As Others have said, oil pump and crank seals would be the first thing I’d check. Followed by the oil pump itself. Next I’d check the OPRV for the correct spring rate and / or to ensure it’s not stuck open. Then I’d start to wondering if the crank was properly cleaned out during the rebuild and / or if any sludge had become dislodged and blocked the oil feed holes.

    What was done in the engine rebuild? Did you do it or a pro? If it was a pro, stop working on it now and take it back to him pronto!

    Was the crank re ground? If so, and error there is a possibility.

    Did you fit new shells? If so were they from a reputable source?
     
  8. Adam_R

    Adam_R

    Joined:
    Nov 20, 2015
    To answer some of the questions
    Kommando - ive not had the heart to strip it further so no idea on the other side.

    The crank looks ok on that picture but it does have some divets in it where the rod has bashed against it. i won't know until i can measure it but on the face of it, it looks to be pretty bad.

    Too late to check the oil, the tank was empty by the time i looked on monday.

    the rebuild was done by myself, so the next few parts i know where done, sludge trap was thoroughly cleaned. no rags etc in the oil tank.

    the crank was indeed re-ground (what can go wrong here?)
    new shells were from RGM norton.

    Build spec was:
    re-grind crank +0.020
    rebore +0.060 and new pistons
    4s Cam with new followers
    all new bearings / shells etc
    as said above i cleaned the crankshaft, all the cases etc, stripped and inspected the pump, new donut seal etc all gaskets were from AN.
    the rods were hand polished but no material was removed.
    breather valve fitted with pipe to oil tank.

    I'll check the other things mentioned in the thread, but it will be next week at the earliest
     
  9. kommando

    kommando

    Joined:
    May 7, 2005
    Kommando - ive not had the heart to strip it further so no idea on the other side.

    Looking for clues as to where the oil starvation started, if the other journal is showing signs of bearing pickup/bluing then the problem is most likely prior to the crank not inside it as the sludge trap is between the 2 journals.
     
  10. JimC

    JimC

    Joined:
    Oct 12, 2007
    How long had you ridden the bike on Sunday before disaster struck?
     
  11. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    What can go wrong? Are you serious? This is a high precision job, one slip of the mic and you easily have too much, or too little clearence. Wrong radius. Poor surface finish. Etc. Too little would result in a seizure like yours.

    I used RGM shells in mine, they’ve been in 4 years and whilst it hasn’t done a million miles, the bike has been rather soundly thrashed. So I think they’re a reputable source.

    On a side note, why do you think it all looks so black in your cases? It looks like it’s done 100,000 miles not 1,000. What’s caused this dya think?
     
  12. Adam_R

    Adam_R

    Joined:
    Nov 20, 2015
    20 miles then a stop for 30mins then 6 miles before it went bang
     
  13. Adam_R

    Adam_R

    Joined:
    Nov 20, 2015
    sorry i worded that wrong, what i should have said was: what can go wrong if the radius is wrong? (im aware it can lead to crank breakage)

    im not sure why the cases are black, i had thought it may have been from the heat of the failure
     
  14. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    If, whilst your bike was parked up, the oil line from your valve emptied into the sump, how long would it take the pump to shift the air lock, prime, and start feeding the crank properly?
     
  15. Kvinnhering

    Kvinnhering VIP MEMBER

    Joined:
    Feb 16, 2011
    +1 on that.
     
  16. Adam_R

    Adam_R

    Joined:
    Nov 20, 2015
    i can see what your saying here, i only turn the oil off if the bike will be sitting overnight. it was definitely on when i started it again (its one of those pre-starting things that sticks in your head)

    It looks like i need to pull the motor and continue the strip down before i find out more. hopeful to update next week
     
  17. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    The damage could have been done in your first 20 miles ? It’s only one hypothesis though.

    Keep us posted as to what you find.
     
  18. JimC

    JimC

    Joined:
    Oct 12, 2007
    My guess would be the oil pump lost its prime when the valve was closed. Those first few miles pretty well knackered everything. Eventually, things went Kaboom! I would NEVER put anything between the oil tank and oil pump. It's quite obvious that engine was running with no oil.

    I had an angry wife, now an ex, that had someone drain the oil from my Commando, unbeknownst to me. I fired up, rode 12 miles at highway speed and suddenly rear wheel lockup. Engine will run with no oil, just not for long. Had some nitwit at a quickie oil change place leave the drain plug out. I drove some 2-3 blocks, out and back to the oil change place. Engine ran for another 75,000 miles.
     
  19. RoadScholar

    RoadScholar VIP MEMBER

    Joined:
    Dec 28, 2008
    My sincere sympathies for your dire situation, you've gone through a wallet full of money and done some hard time with the re-build; I suggest that you find a quite place and get drunk, see if you can turnoff some of the pain for a while and contemplate your next set of moves.

    Your pictures seem to show a large hole in the case(s), probably not repairable, certainly I can't tell from the one picture. The crank is probably toast, rods, probably can't trust the pistons, and with the barrel out to +.060 it will need a sleeve, if not cracked. Nice if the head can be re-used, assuming that a piston, or debris, didn't muck it up. I see no reason to be optimistic; a super bummer with the riding season (north of the equator) just getting started.

    Probably less expensive and more expeditious to source another engine...
     
  20. concours

    concours VIP MEMBER

    Joined:
    Dec 29, 2011
    Another example of an oil pressure gage could have saved the engine.
    It could have VERIFIED oil pressure directly after/since rebuild, and a definate trend could have been seen before "clatter".
     
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