Engine failure

Discussion in '2nd Generation: 2007+ R55 through R61' started by Williamc, Nov 29, 2019.

  1. Williamc

    Williamc New Member

    Nov 23, 2019
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    Just finished new timing chain and cylinder head decoke rebuilt as per manual replaced all bolts etc done the usual two revolutions of engine re check timing which was fine so done the final torque on the cam pulleys re checked again fine cars been starting fine took it for its mot after mot drove about 2 miles broke down checked compression and there’s none so I set the timing back up to find both camshafts out slightly and exhaust valves are bent so gutted back to square 1
     
  2. wmwny

    wmwny Well-Known Member

    May 29, 2009
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    Sorry about your mechanical problems, but, Welcome to M/A!

    All o my MINIs are Generation 1's, so I cannot be of any help, but, there are many on here who can offer the suggestions you need....good luck!
     
  3. MCS02

    MCS02 Moderator
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    Jul 31, 2009
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    Sorry to hear this. It sounds like the chain slipped. When I did my timing chain that was my big fear. It still is when I think about it. I cant believe the only thing that keeps it from slipping is the bolts being tight, I would prefer a key.
    on the bright side sense you have to pull the head maybe you should through a big valve head on there. :D

    Good luck keep us up on what you do.
     
  4. Williamc

    Williamc New Member

    Nov 23, 2019
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    Sorry for being ignorant what’s the difference with the big valve head apart from valve size obviously and does it come off another model ?
     
  5. Minidave

    Minidave Well-Known Member
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    Dec 22, 2009
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    He's referring to an aftermarket cylinder head - it sounds like you're in the UK and most of us are here in the States. Over here, RMW is one such company that sells a big valve head for the Cooper S, but I don't know if they do them for the turbo era cars.
     
  6. Williamc

    Williamc New Member

    Nov 23, 2019
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    Hi yes I’m in the uk will just do this one again then would have been interesting finding out a bit more about that though
     
  7. Jeff10049

    Jeff10049 New Member

    Nov 24, 2019
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    Did you replace the sprocket bolts and crank bolt? They are torque to yield fasteners so they stretch when torqued some of that springs back when loosened but not all of it so the bolt becomes longer when reused they can sometimes bottom out in the cam so when you do the final step you are simply twisting the bolt not applying pressure to the gear. Same with the crankshaft bolt.
    This will cause the gear to slip later on if you absolutely had to reuse a cam or crank bolt thread it in first to make sure it goes in deeper than the gear is thick if not grind some off. But remember Its already yielded once twice is pushing it.
     
  8. MCS02

    MCS02 Moderator
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    What @Minidave said. It will make your mini produce more power, and well you can never go to fast. RMW does make one but once you go down the rabbit hole of modding your mini you will be addicted.:D

    http://store-revolutionmini-com.3dcartstores.com/R56-CNC-Big-Valve-head_p_65.html

    I know I am not helping.......sorry.
     
  9. Williamc

    Williamc New Member

    Nov 23, 2019
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    Hi thanks for the reply I replaced all the bolts and torqued them according to auto data seems to have bent all the exhaust valves for some reason
     
  10. Jeff10049

    Jeff10049 New Member

    Nov 24, 2019
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    That just sucks I have a manual at the shop I can double-check the torque process compared to all data for you Monday. Something slipped unless it was the chain but I can't see that happening very easily.
    You said both cams out slightly so I think crank pully is what moved or chain jumped on the crank pully but man it would have to be way loose.
    I do remember reading something about the early crank bolt spec calling for 100 degrees of rotation after initial torque and that was a misprint and it should be 180 but don't hold me to that until confirmed.
     
  11. Jeff10049

    Jeff10049 New Member

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  12. Williamc

    Williamc New Member

    Nov 23, 2019
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    Hi that would be great if you had those torque settings I don’t think the crank bolt came loose because I put a red paint dot on the bolt and one adjacent on the pulley just as a visual and none of them have moved also the chain is so tight it must have been the cam pulleys that’s moved slightly but can’t understand how it’s just the exhaust valves that bent
     
  13. Jeff10049

    Jeff10049 New Member

    Nov 24, 2019
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    The bolt or balancer would not have to move just the gear if the clamping force was not tight enough. Was your spec the 50nm and 180 degrees rotation on the crank bolt? If it was the incorrect 100 degrees that could do it.

    Here are all the torque values.
    Damper Hub to Crankshaft - Use New Fastener
    Stage 1 = 50Nm (36.8 ft-lbs)
    Stage 2 = additional 180deg of rotation

    Exhaust Sprocket to Camshaft [N14] - Use New Fastener
    Stage 1 = 20Nm (14.7 ft-lbs)
    State 2 = additional 90deg of rotation

    VANOS Unit to Intake Camshaft [N14] - Use New Fastener
    Stage 1 = 20Nm (14.7 ft-lbs)
    Stage 2 = additional 180deg of rotation
     
  14. oldbrokenwind

    oldbrokenwind Active Member

    Oct 18, 2012
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    Might also check the vacuum pump, they've been known to lock up causing bent ex valves. I had the crank bolt work loose after using the wrong torque spec. Found one of these to help keep the bolt from loosening.

    57168384_2549905775043100_7013905753006145536_o.jpeg
     
  15. MCS02

    MCS02 Moderator
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    When I did mine I want 180 deg. I wish I had know about the CravenSpeed part.
     
  16. Williamc

    Williamc New Member

    Nov 23, 2019
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    Hi Jeff thanks for the info when I’m rebuilding I will probably just renew the crank bolt again because there’s probably no way of telling if the torque is correct now so probably safer to renew
     
  17. Williamc

    Williamc New Member

    Nov 23, 2019
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    Hi thanks for the info will look into the cravenspeed part and when I had the vacuum pump off it was certainly turning ok
     
  18. Jeff10049

    Jeff10049 New Member

    Nov 24, 2019
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    what spec did you use last time? if it was the 100deg spec you can reuse it as it was never stretched to the point of yield. But if you're re-ordering cam bolts why not get all 3 cheap insurance I suppose
     
  19. Williamc

    Williamc New Member

    Nov 23, 2019
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    I can’t remember but I’m just going to replace all 3 to be safe
     

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