FH770D Bent push rods I need a solution.

Discussion in 'Mechanic and Repair' started by captken, Oct 5, 2012.

  1. mowermankevin

    mowermankevin LawnSite Senior Member
    Messages: 270

    Wow, finally, Captken you probably opened a can of worms on this one. I've tried for years to figure this out and the only two guesses after I've been able to come up with on a multitude of Kawas is what is the difference between this and a Kohler ?, (tappets instead of hydraulic lifters), and ambient temperature. The engine can start and run beautiful until the temp drops, (like today) and sometimes the only way to pop 'em off is with ether & sometimes not even then. Read a bunch of interesting possible solutions on here, but I don't believe you bought a bad engine, every damn Cow-a-socky I been around has developed this problem sooner or later. Keep us posted because I'd love to know the fix as would a lot of lawnsite mechanics, Good Luck
  2. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,337

    Kevin...its just an engine..the tough part is trying to diagnose it without being hands on....
    I'm quite confident that I...like a few other techs on this site ....could find and repair the problem in short order if it were sitting on my bench...
    The thing is...there can be 20 different solutions for an engine that sounds like it has the same issues...
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  3. Sharpcut 1

    Sharpcut 1 LawnSite Senior Member
    Messages: 452

    I'm with Fish on this one. Seen it many times on v-twin Kawi's. Valve guide slid in head and is binding up, causing pushrod to bend.
  4. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    You hit that nail on the head Slapper....... Way too many times I've sat here reading a thread and wished I could just hear a engine in question run.

    Having a engine or machine in front of you to see-hear-touch makes a world of difference.....

    Oh...... Wind was blow'n from the south today, Was that BBQ I was smell'n while try'n to work ?!?!
  5. BigFish

    BigFish LawnSite Platinum Member
    Messages: 4,191

    If you gotta use ether, sumpin aint right, period!!
    I've never owned a can of ether! ( ok, I lied! when I was OTR truckin', I did )
  6. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,337

    Normally I would agree with you guys....but...valve guide isuues normally show up on high hour engines...this engine is virtually new...
    It appears this engine was used to test exhaust systems...decibel levels..
    It is conceivable that the engine was run without a muffler for an extended amount of time...which would make the engine temps higher than normal..and possibly allow the valve guides to slip...and...if it was ran with no load and no backpressure on the valves...it would surely backfire from time to time which could shear the flywheel key....
    Still trying to figure out why the engine wasn't operated at 3650 rpms out of the box...the top of the torque curve is around 3350-3400 rpms...anything below that is dogging the engine...
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  7. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,337

    Sounds like the acutely trained senses of a mastertech at work...always on the job...
    Posted via Mobile Device
  8. captken

    captken LawnSite Bronze Member
    Messages: 1,704

    I will check the flywheel key tomorrow, then go from there.
    I pulled the oil filter off and drained the oil in a black pan. Found milky dust like shimmers in the oil.
  9. captken

    captken LawnSite Bronze Member
    Messages: 1,704

    forgot to add what you already know, its metal. Magnet test produced weird result, hover magnet over shimmers, no effect. Wave the magnet back and forth a few times, discoloration clears up. I don't know if this is a clue or normal for break in. I just installed a tiny tach just got it ordered in after the first bent push rod. I set the engine up out of the box and it sounded like 3600 to me. Judging by the kawasaki on my Hustler Z, But maybe over time, I think 2 tank fulls of gas or about 16hrs run time, maybe the rpms slipped. The hr meter on the machine does not work.
    thank you all very much for your help.
  10. captken

    captken LawnSite Bronze Member
    Messages: 1,704

    I tried the other head that I thought was good, after taking it to the cylinder head shop for them to check it out.
    Bent push rod as soon as I advanced the throttle.

    So I opened up the engine case. This is what I found...nothing...at least nothing that I can see wrong.

    The dots lined up on the crank and cam in these pictures, also of flywheel. I did not take off the flywheel, you can see the keyway and key and they look okay.

    Is it possible that the gear slipped on the crank?

    I was told by an engineer at the assembly plant that this engine was in fact the 15th engine of this type built.

    This is what he said in today's email. And yes, I was able to push the valve down further...

    Were you able to open the valve any further after the cam opens the valve to it max lift?

    Has to be the cam timing. I am trying to think of some way you can check if the crank gear has slipped.

    You can run the engine on a bench before putting it back into the machine. Just bolt down with a couple bolts. a fuel line, power to the starter and carb and it will run. I do it at home all the time.

    Your engine has several people here baffled.

    problem kawasaki 007.jpg

    problem kawasaki 006.jpg

    problem kawasaki 002.jpg
    Last edited: Oct 10, 2012

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