MTD mower vibrating

Discussion in 'Mechanic and Repair' started by dhodson2004, Aug 2, 2006.

  1. dhodson2004

    dhodson2004 LawnSite Member
    Posts: 24

    Hello. This is my first post. If any other info is needed, don't hesitate to ask. I just got an MTD riding lawn mower, 5 horse B&S, 6 speed with a 26" deck. The tag under the seat says Model# 137-501-120/D297H. When it is running, there is a horrible metal clanking noise and a bad vibration through out the whole tractor. I have to SLOWLY engage the blade or else it will stall. Once engaged, there is a tremendous power loss as the motor boggs down. Then there is a trail of blue smoke out of the exhaust while engaged. If I disengage the blade, the power is back and no smoke. The deck belt ended up getting spit out. I put it in neutral and set the parking brake and then looked under it. I noticed the shaft coming off of the motor which has the deck belt pulley on it was vibrating and sparking. I tightened it up, put the belt back on and started it up. It wasn't vibrating anymore. I engaged the blade and it seemed better. A couple seconds later, it was vibrating again and I disengaged the blade. It spit the belt back off of the motor pulley. :dizzy: If anyone has any ideas, please let me know. Like I said, this is my first post so please be patient. Thanks in advance!

    -Dan
     
  2. mike lane lawn care

    mike lane lawn care LawnSite Bronze Member
    Posts: 1,707

    sounds like a few separate problems, one sounds like the clutch, it may need to be adjusted or replaced, this could be the cause of that horrible vibration and noise. the second could be the carb. check it out, tune it up, and check things like oil level, spark plugs, fuel filters. a loss of power that drastic sounds like either the carb is gumed up, or a spindle or bearing on the mower deck is failing/failed.
     
  3. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,023

    Sounds like the crank pulley has been run loose too long and has beat it's self out, Hopefully the crankshaft is OK. Remove the pulley and inspect the crankshaft, If good replace the pulley. Once a belt gets thrown off there is less chance of it ever staying on, It damages the inside cords so that will probably need replacing also. The smoking under load may go away once the new pulley is installed and not rubbing on anything.
     
  4. Jim@MilkyWay

    Jim@MilkyWay LawnSite Senior Member
    Posts: 472

    Take the belt(s) off the motor shaft, and remove deck, if possible, to get it out of the way, then grab the bottom of the motor shaft and try to jerk it back and forth in all directions.
    Let us know if it will "rattle" in any way or if you can move it side-ways, in _any_ direction, _any_ amount, at all.:rolleyes:
     
  5. Jim@MilkyWay

    Jim@MilkyWay LawnSite Senior Member
    Posts: 472

    Oh, Err,, Uhmmm,,,
    By the way, glad to have you with us, If you stay tuned long enough, you will find that these guys _know_ their stuff (Rob).
     
  6. dhodson2004

    dhodson2004 LawnSite Member
    Posts: 24

    Once the pulley came loose and started vibrating again, I could move it sideways about ¼ of an inch. I tightened it again and then tried to move it. There is now no play in it. I can't tighten it very much because I don't have three hands. I thought about me holding the pulley in place with gloves and having someone else tighten it with the impact wrench. The problem I see is that it is not tight enough and vibrates loose. It is ok once I tighten it, then it comes loose. Let me know if this sounds like something worth trying. Thank you all for the responses! I GREATLY appreciate them!! :)
     
  7. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,023


    Go back up and read my post and do as it says, I'll bet you a quarter thats what you will find.....
    With the bolt slap out on the ground you should have no side to side movement in the pulley.....
    Once the pulley is worn like this nothing will keep it tight......
     
  8. Jim@MilkyWay

    Jim@MilkyWay LawnSite Senior Member
    Posts: 472

    Remove the pulley from motor shaft, jerk shaft hard back and forth to make certain the motor shaft itself will not shift,, _at all_ . If you get any amount of shaft shift, then you have a bad crank bearing. Now inspect the flat, on the crank shaft where pulley fastens to it. If I were to guess, I would bet you need to take a mini grinder with a corundum cut-off wheel, and dress the flat. If the crank shaft has "wallerd" out all the way around, where pulley has spun excessively, then you are probably screwed, as you will never again center pulley on shaft, nor will you ever stop vibration. If crank shaft OK, then... remove and inspect the screw/bolt, and key or whatever is supposed to tighten and hold pulley against the crank shaft. It may be at least partly stripped.
    You probably should replace pulley assembly and key, tighten to spec with medium-hold lock tight on threads, have a nice day.:clapping:
     
  9. Jim@MilkyWay

    Jim@MilkyWay LawnSite Senior Member
    Posts: 472

    Sorry Rob.;)
    I had already started the above reply before I ingested all of yours.
     
  10. dhodson2004

    dhodson2004 LawnSite Member
    Posts: 24

    In the morning I will try to get the shaft and pulley assembly off. It doesn't look simple with the other belt still on the top pulley on the same shaft. After I get it off and inspected, I'll post back. Thanks again!

    -Dan
     

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