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Hydraulic problem Exmark Lazer HP 2006 model

Discussion in 'Mechanic and Repair' started by Bassman, Dec 21, 2007.

  1. Bassman

    Bassman LawnSite Senior Member
    Posts: 270

    Have a problem with hydraulic drive on one side fading out after mower gets hot. Reservoir is full, no leaks and hex lug on pump is tight. This only happens after operating for about 2 lawns when it's hot. If it cools down it functions ok again until hot.

    The mower is under warranty but my dealer is closed until after the new year.
    Just wondering if anyone has experienced this or have an opinion what it could be.

    Thanks for any input.
  2. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Posts: 11,062

    You got major issues boss...

    May as well haul her in now before it goes.
    Time to make use of that warranty.
  3. Bassman

    Bassman LawnSite Senior Member
    Posts: 270

    I do believe I'd have to agree with you my friend.

    Merry Christmas.
  4. bigmower1

    bigmower1 LawnSite Member
    Posts: 158

    Take it back for warranty service. Chances are it is one of the hydro pumps and they are very expensive. Usually pums loose their power after they get hot because the pistons in them are seizing or the back plate they ride against is all scorched. Probably both. They will replace the bad pump.
  5. lucforce

    lucforce LawnSite Member
    Posts: 223

    Wow. Don't see to many piston-type hydro pumps.
  6. bigmower1

    bigmower1 LawnSite Member
    Posts: 158

    You havent seen to many piston type hydro pumps? Well when your toro, exmark, scag, etc. pumps go, take them a part and you will actually see five pistons in them. I rebuild many hydro pumps, and some are the ball type and some are the piston type. What usually causes the piston type pump to fail is a thrust washer that goes bad and sometimes people even replace the thrust washer and put it in wrong because the thrust washers are not the same size. The bearing case usually goes bad and can easily be fixed if caught fast enough and the part is only thirty dollars and after it is replaced, its like having a new pump all over again as long as you get all the metal powder out of the system.
  7. lucforce

    lucforce LawnSite Member
    Posts: 223

    Well, all kidding aside, the pumps that we are talking about are not called "piston pumps." This is simply because the term is left for "standard" crankshaft, rod, piston, and cylinder arrangements. The axial pump that we are talking about is not the same arrangement.

    Semantics aside, depending on the model and belt arrangement, you can have belt slippage on one pump pulley more than the other. This is due to belt routing. I would look closely at the pulleys and belt (including tension). A lot more belt problems occur than pump failures.
  8. bigmower1

    bigmower1 LawnSite Member
    Posts: 158

    I agree, that is possible, but rarely happens. I don't know the exact terminology used to call the type of pumps, but I did explain to him how the pump works and the common problems with them, and all i know how to do is diagnose the problem and fix them if they fail. I think he said it was an Exmark and they have the type of pump i was talking about. If the belt is on properly, it shouldn't really slip, unless the tension isnt working or a stick or something like that happens to pop the belt off. Sometimes the set screw on the pulleys get loose and the pulley can also slip on the pump, but most people can tell if the belt is loose or the pulley isn't on the pump i think. The mower has a warranty and he should definitely take it back for warranty repair. I do appreciate the information you gave me about the name of the pump and the possible other causes.
  9. sawman65

    sawman65 LawnSite Senior Member
    Posts: 751

    may be the belt there was a service bulliten on that a year or two ago mainly the 52" and any that run a vac system.there is a kit to fix it.
  10. Bassman

    Bassman LawnSite Senior Member
    Posts: 270

    Thanks for the tips.

    Just got it back today. The thrust bearing in one of the hydro pumps failed. Exmark apparently released a service bulletin addressing this problem. Warranty covered it.

    How can consumers access Exmark service bulletins?

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