Crash leads to valve pushrod misalignment

Discussion in 'GS Boxers' started by farmerger, Jul 10, 2013.

  1. farmerger

    farmerger Snowed in Adventurer

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    Dumped my 06 !200GS going across a small creek last weekend. Landed heavy in some rocks on the left side. Bent the HB crashbar back into the left valve cover cracking it open. Immediately started making this odd clicking noise until I could shut it down. Trucked it home and started disassembling the left head. When I removed the busted valve cover I found that the intake valves were partially open even at TDC.:eek1 Closer examination showed why, (sorry OCD got the better of me and I didn't take any photos while tearing things apart); the intake valve pushrod had fallen out of position and was now jammed crooked between the cam follower and the rocker arm. As result it took off a little bit of head material at the rocker end and left a circle of divots in the follower bottom.:huh

    [​IMG]

    The pushrod head had one small blemish on it, nothing on the rocker. Its on the right side of the rod lying half way on the blue towel, towel end.

    [​IMG]

    Questions: Can I put things back together and write if off as just a fluke inertial thing causing the rocker to have moved too far out due to the left side crash or is something else wrong to have allowed this to happen? Can I reuse these parts or do I need a new pushrod and follower? I will clean up the burrs on the head before reassembling. Finally, should I take off the head and check the valves and piston, or am I basically at the point where if those are shot I'm calling up the insurance?:ear
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  2. def

    def Ginger th wonder dog

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    I would tear down to the next level and inspect the followers further. Next, did you perhaps have valve/piston contact? You'll need a compression test to determine that.

    Seems like there were some rather severe forces at work when you crashed. If fiction parts are blemished at rubbing or bearing surfaces, they should be replaced.
    #2
  3. JM

    JM Been here awhile

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    You're talkin some high rpm parts here. Not an area I'd gamble with.

    Just sayin
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  4. def

    def Ginger th wonder dog

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    The RPM is not that high...remember, the cams rotate at half crankshaft RPM.

    I would not rate the boxer a high RPM engine.
    #4
  5. JM

    JM Been here awhile

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    I didn't know that. Thanks for the info.
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  6. JimVonBaden

    JimVonBaden "Cool" Aid!

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    I agree. This is not a common issue with even a hard drop from what I have seen. Definitely want to do a compression check at a minimum. The "divots" you refer to look to be in a wear area. If this is the case, those parts will fail in short order and need to be replaced.

    Jim :brow
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  7. farmerger

    farmerger Snowed in Adventurer

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    Will do a compression test tonight. What numbers should I be looking for?

    Anyone ever took a head apart? What does the backside of the follower, the side against the cam, look like? Is it made from two different hardness steels, cause that's what it looks like from the pushrods end, the part where the rod sits in the follower bottom is a darker grey and has no marks on it, only the lighter coloured metal around it?

    Appreciate all your advice fellas, thx.
    #7
  8. AntonLargiader

    AntonLargiader Long timer

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    Most likely when the rock punctured the valve cover it kept the rocker from closing and the resultant slack allowed the pushrod to drop out of position. But then the lifter and mispositioned pushrod may have tried to lift the valve too far and hit the piston. Dents in the lifter are bad news. Here, I would disassemble the head.

    Insurance? That's your call. Depends more on your repair ability than on the damage.
    #8
  9. farmerger

    farmerger Snowed in Adventurer

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    Well, disassembly is complete. Both intake valves contacted the piston. Will get some pics up tomorrow. I don't see any damage to piston or valves, basically looks like it just knocked the combustion built up off where the contact was. I haven't taken a close look at the follower yet but there is a thin line on the camshaft lobe for it. Again I will post pics so you guys can give me your opinions on how screwed I am.:1drink
    #9
  10. SpeedySteve

    SpeedySteve Been here awhile

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    Subscribed...
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  11. xppx

    xppx Adventurer

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  12. Twilight Error

    Twilight Error Going nowhere slowly

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    I look for consistency when I check compression. The actual number is influenced by the volume of the tool you're using - a longer hose will give a lower reading than a short hose. Compare the heads, if they're both in good condition, they'll be nearly identical.

    Pulling the head is easy peas - place the engine at TDC, remove the cam sprocket (I use a small ziptie to secure the chain to the sprocket), remove the fasteners holding the head to the cylinder and pull straight out. You're already in the job for a new pushrod and follower, add a head gasket to the parts list.

    Oops. Didn't see the followup.

    Hold the head vertical with the intake port facing up and pour some kerosene into the valve area. If it doesn't leak, chances are your valves are okay.

    As far as the piston goes, clean the carbon off and see what the crown looks like.
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  13. JimVonBaden

    JimVonBaden "Cool" Aid!

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    I would pull the piston and have it checked. There may be damage you can visibly see. You are this far into it. Also check your valves for trueness. One might be bent at the stem/head from contact.

    Replace all damaged parts, www.beemerboneyard.com might have them reasonably priced.

    Jim :brow
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  14. farmerger

    farmerger Snowed in Adventurer

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    Here is the piston

    [​IMG]

    and the valves

    [​IMG]

    line on intake cam lobe, note its not on the raised part of the lobe

    [​IMG]

    OK lets hear it.:ear

    Jim, pull the piston, is there a JVB pictorial or video on that?:wink::lol3
    #14
  15. JM

    JM Been here awhile

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    Following with interest. :lurk
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  16. bdarling

    bdarling Weatherman

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    Here is a great writeup from another inmate:
    http://www.advrider.com/forums/showthread.php?t=634348

    I've been into my left cylinder more times than I care to remember, but it's an easy job. Just be mindful of the timing chain rails when you're sliding the cylinder back on, they can hang up on internal sections of the cylinder casting.

    Also, I would advise that you remove that cam chain tensioner before you start wiggling stuff. I'm not sure if the piston has room to come loose with the head disassembled, but you don't want to go fishing for it.

    -Blake
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  17. JimVonBaden

    JimVonBaden "Cool" Aid!

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    It is a shame you didn't compression test it first, you would then know if the valves were bent.

    While it doesn't look too bad, a damaged valve, or cracked piston can seriously ruin your day if it lets go while running, basically putting crap all over your motor.

    I would still have them checked.

    Jim :brow

    PS "a video on this" Ha ha ha, how original! :rolleyes
    #17
  18. Twilight Error

    Twilight Error Going nowhere slowly

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    :nod

    The valves hit the piston, those parts should be treated as suspect until they're proven okay. Even then, I would probably replace those parts - they're a lot cheaper now than in addition to a lot of other bits when one lets go...
    #18
  19. AntonLargiader

    AntonLargiader Long timer

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    I have seen plenty of smacked valves on Oilhead motors and none of them involved piston damage (beyond the scarring that you see on the rim of the pocket). However, at this point pulling the cylinder is pretty simple.

    Not sure about the cam, but I can't see it too well. I would look at it really close and also the lifter. Furthermore you don't know if the guides got whacked, etc. You have to look at everything.

    If you let a shop handle this (if you went the insurance route) they would probably replace the piston since it shows damage. Heck, they might replace the head and nearly everything else, figuring that there may be unseen damage.

    Dunno what your deductible is but you're already in for a valve cover, two valves and a head gasket. $350+.
    #19
  20. farmerger

    farmerger Snowed in Adventurer

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    Been reading the repair manual and did some quick pricing....holy smokes...BMW says to replace the piston and cylinder as they are a matched pair in size. Also, to get the correct piston you have to pull and weigh the right piston, again the two pistons have to be within 10 grams of each other in weight. Put all this together plus parts (which are of course way more expensive up here in Canuckistan) add in shop labour and I'm looking at upward of $4k I think. The piston cylinder set alone, in US prices, is almost $1200. Time to call the insurance.:cry
    #20