LT155 No start strange puzzle
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    mackguy's Avatar
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    LT155 No start strange puzzle

    Posting here on behalf of my brother with a dead LT155..

    Story as I've understood it

    1) was recently serviced and running fine
    2) his son was mowing with it, stopped and turned it off to go do something, everything normal to this point
    3) Went back out to start it, and reports a "loud rattle" but no start, engine cranking OK

    His diagnostic steps so far

    1) checked spark at spark plug by grounding to engine.. There is spark
    2) Tried starting with starting fluid.. nothing..
    3) replaced some crank key that apparently affects timing?

    Now, he says with thumb over spark plug hole there's no obvious air movement, which might indicate low compression, or that there's no piston moving, but it seems like something so dramatic as a broken con-rod, crank etc, would make a terrible racket when turning over..

    Doesn't seem to be a fuel problem since he's tried starting fluid.

    His next step is to remove the head and inspect for damaged valves/piston etc... Any other diagnosis he can try before that?
    1993 LX176 - 3rd generation family ownership

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    T-Mo's Avatar
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    The loud rattle noise he reported is an indication of something internal, or at least, something just not right. I'm betting a broken rod. Does it crank really fast? With low or no compression, it's something internal.
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    1965 110s, 1966 110, 1967 112, 2001 LT150, 2003 GT245, 2004 GX345, 2006 X320

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    mackguy's Avatar
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    Claims it's cranking normal, and no unusual noises (the "rattle" was reported by his 11 year old son, not something he heard)
    1993 LX176 - 3rd generation family ownership

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    You know how kids are. The slight rattle could have been a loud bang. Lol

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    Might be a valve hung open or dropped. Or, you lost timing between valvetrain and crankshaft.
    1025R FILB, vintage: 2015
    54D MM mowing deck
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    mackguy's Avatar
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    Quote Originally Posted by Jeff B View Post
    Or, you lost timing between valvetrain and crankshaft.
    This really seems the most likely to me..

    Sounds like it's time for a tear down. Was just wondering if there was some possible sensor or electrical connection that could throw it off..
    1993 LX176 - 3rd generation family ownership

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    Quote Originally Posted by mackguy View Post
    This really seems the most likely to me..

    Sounds like it's time for a tear down. Was just wondering if there was some possible sensor or electrical connection that could throw it off..
    Are you sure you have no vacuum or compression at the spark plug hole?
    1025R FILB, vintage: 2015
    54D MM mowing deck
    Imatch hitch
    2 inch receiver for three point
    "18" cart
    Piranha Tooth Bar
    Ken's hooks and differential lock pedal
    Artillian 36" forks
    Stihl equipment: Saws; MS261C, MS462C, MS661RCM and Blower; BR600 and Trimmer; FS70R and Hedge Cutter; HL 56K and Pressure Washer; RB400
    Husky log splitter

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    mackguy's Avatar
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    Not at all, he just said he didn't feel much air movement with thumb over it.


    Sent from my iPhone using Tapatalk
    1993 LX176 - 3rd generation family ownership

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    Quote Originally Posted by mackguy View Post
    Not at all, he just said he didn't feel much air movement with thumb over it.


    Sent from my iPhone using Tapatalk

    I had a buddy 30 years ago who used a carved up wine cork just for testing this, push it in and crank and if it pops out she's fine. This was back before we could afford real compression testing equipment.

    You could stick a drink straw in the cylinder to see if the piston is fully stroking.
    Last edited by Jeff B; 04-14-2016 at 07:30 PM.
    1025R FILB, vintage: 2015
    54D MM mowing deck
    Imatch hitch
    2 inch receiver for three point
    "18" cart
    Piranha Tooth Bar
    Ken's hooks and differential lock pedal
    Artillian 36" forks
    Stihl equipment: Saws; MS261C, MS462C, MS661RCM and Blower; BR600 and Trimmer; FS70R and Hedge Cutter; HL 56K and Pressure Washer; RB400
    Husky log splitter

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    mackguy's Avatar
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    Head is off along with flywheel. When I was turning over the motor using the puller for the flywheel, the piston didn’t turn with any frequency. Once in a while, the turn would get tight and it would go back up. Seems like it is an issue with the crankshaft. Perhaps a bearing is failing and preventing the crank from moving correctly? It certainly does not seem right.
    I'm guessing broken connecting rod, but wouldn't rule out a sheared, or badly damage crank..
    1993 LX176 - 3rd generation family ownership

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