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What is wrong with my Toro Proline 21"

Discussion in 'Lawn Mowing' started by outrunjason, Apr 9, 2003.

  1. outrunjason

    outrunjason LawnSite Senior Member
    from dallas
    Messages: 719

    I bought this mower about 2 years ago. When I bought it a put a clock on it to keep up with the hours. It now has about 350 hrs on it.

    THE PROBLEM: It is very hard to start. Once started it runs at a good speed of about 3,400 rpm. As soon as you hit the grass it losses half the rpms and in even higher grass tries to die. When I pull the cord to start it, it is very easy. Unlike my other proline it is very hard and it will even give you a kick back sometimes. Also when I turn the blade underneath it almost turns around freely like no compression.

    DIAGNOSIS: I am guess that there is either no compression anymore or the sheer pin has come off and it is not firing right?

    QUESTION: I really don't know what is wrong with it. Has anyone else had this problem? What do you think is wrong with mine?

    Commercial Pro Line 21 22040

    Thanks, Jason
  2. FrankenScagMachines

    FrankenScagMachines LawnSite Platinum Member
    from IN
    Messages: 4,739

    How does it act during starting compared to normal? It may be flywheel key but also put in a new, properly gapped spark plug and torque correctly. Have a dealer check the head gasket, head bolts torque and the valves and if possible have the carb adjusted (some cant be adjusted) but it doesn't sound like carb. I say check the head gasket and bolts and check spark plug is tight and check valves.... a sticking exhaust valve would do that as well as loose spark plug or head bolts or bad head gasket....
  3. outrunjason

    outrunjason LawnSite Senior Member
    from dallas
    Messages: 719

    Wether it is a cold start or a warm start it is the same start just hard. It will kinda start a low rpm start and then die. I am thinking kinda in your direction that is might be internal. I thought about just buying a block and going that route but it only has 350 hours on it and I think it should be able to get more out of it.

  4. FrankenScagMachines

    FrankenScagMachines LawnSite Platinum Member
    from IN
    Messages: 4,739

    Doubt it's that serious... much easier to fix than to replace the whole block.... also check the ignition module... check the carb if it's clean. The crankcase breather valve probably could be checked but shouldnt be your problem...
  5. MWHC

    MWHC LawnSite Member
    from Wyoming
    Messages: 218

    Does the unit have a Blade Brake Clutch? If so, the blade spins independent of the crankshaft. If the blade spins with little or no resistance when turned off it means your brake pad is probably worn out or out of adjustment. Next problem. Hard rought starting - Is this unit a 2-cycle? I would look into carbon build up on the exhaust port. Also change spark spark plug (gapped correctly) and take apart the carb and clean that.
  6. greengrass2003

    greengrass2003 LawnSite Member
    from VA
    Messages: 19

  7. bastalker

    bastalker LawnSite Senior Member
    Messages: 965


    Its probably the shear pin..
  8. FrankenScagMachines

    FrankenScagMachines LawnSite Platinum Member
    from IN
    Messages: 4,739

    I hadn't thought about the BBC. Some engines like Lawn Boy 2 cycles will not start or run right if the blade gets loose from the shaft, but that doesn't go for mowers with BBC's. As MWHC also said may be muffler.

    Bastalker, loosen up my man I was just listing some possibilities :rolleyes:

    I have one more question, did this happen suddenly while you were mowing or gradually? Or did it just do it when you pulled it out of storage?
  9. gator007

    gator007 LawnSite Member
    Messages: 3

    you probably have a corbon buildup in the exhaust manifold and muffler. to claer this, you need to start it, then take a screwdriver and scrape the inside of the muffler and jam it in there until no carbon comes out. Then take the muffler off and look at the area on the block to see how much carbon is built up. scrape that area free from carbon, but dont damage the piston. then make sure you are running a proper ratio off oil to fuel mixture.{ to much oil will build up alot of carbon iff the engine does not run hot enough. If your engine kicks back, like your other mower does, you probably have a bad shear pin. these mowers are great if you take care of them. I change my filter every day.
  10. specialtylc

    specialtylc LawnSite Bronze Member
    Messages: 1,656

    Could be the govenor not working.I had a similar problem with a Honda.

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