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Toro Prolines 21" knock

Discussion in 'Mechanic and Repair' started by whitleys, Jan 11, 2003.

  1. whitleys

    whitleys LawnSite Member
    from Kansas
    Posts: 55

    I have 3 Toro Proline 21" WB's. Bought all three new. After about a year they start rattling and I notice some loss of power. I am using Amsoil 100:1 ( I searched the threads and hear that advice but I have been using 100:1 since the units were new.) Any advise? Has anyone torn down one of these suzuki's and cleaned out the head?
    Thanks for your help.
  2. khouse

    khouse LawnSite Bronze Member
    Posts: 1,465

    I haven't had any problems using Amsoil 100 to 1 in almost 20 years. When your measuring oil it's easy to not use enough and maybe you could be running 110-125 to 1 mixture. You can always be sure and run it 80 to 1 then if you or your help don't get enough oil - you would have a buffer to cover you. I mix it anywhere between 80 to 100 to 1. Either way you won't have to clean the exhaust port.
  3. SWD

    SWD LawnSite Senior Member
    Posts: 989

    I have worked on Prolines that knocked and rattled before and found two seperate problems contributing to the noises made.
    The carbs were extremely fouled and this was effecting the govenor mechanism.
    The second problem was the head/piston were fouled with the heavist carbon deposits I have ever seen.
    Basically, all I did was clean them up, checked all the hardware, and they didn't rattle any more.
    As far as the suzuki motors, breaking into them were not problematic as I recall. Suzuki makes the motors for Allen brand Hover mowers and other utility pieces and it is a similar unit.
    It was a straight forward disassembly.
    What I would check beofre breaking into the machines would be the underneath of the deck. Check for all the mounting bolts to be in place. Also check them for tightness. I seem to remember one of the machines being slightly loose in this area and it sounded just like a bearing knock.
  4. Green Pastures

    Green Pastures LawnSite Silver Member
    Posts: 2,457

    Not flaming and I don't want to get into any full scale war on oils.
    I run my Prolines with either Echo or Stihl oil mixed 50:1 just like the MANUAL say's to do.

    Both are two seasons old and don't make any knocking sounds, start at the 1st or 2nd pull and get good mileage. There is little to no deposits when I change the plugs.
  5. xpnd

    xpnd LawnSite Senior Member
    Posts: 378

    If it is rattling and not a knock check the crankshaft protector on the underside of the mower. It is attached to the deck with three bolts and more importantly a star lock washer under each of these bolts. Also when doing the winter PM it is a good idea to remove the blade adapter and pull this plate. You will be amazed at how much garbage accumulates between the crankshaft protector and the engine base. This chaff only serves to prematurely wear the belt.
  6. outrunjason

    outrunjason LawnSite Senior Member
    from dallas
    Posts: 703

    I didn't even know mine was knocking. One day I was mowing next to another company and they passed by me with there toro proline and it sounded so different than mine. I realized mine was running at lower rpms. I uped the rpms to around 3200 or so and now it does not knock near as often. I also put just a little more gas than oil in the mix. I mix 5 gallons at a time but now I mix just a little over 5 gallons.

  7. landcruiser

    landcruiser LawnSite Member
    from Tx
    Posts: 134

    I have been into so many of these 2-stroke Suzukis on the 21" Toro Prolines you wouldn't believe it. Here's the deal. More than likely your "knock" if actually crankshaft endplay you hear due to worn crank bearings. There is an upper and lower crank bearing and after they get worn, they allow the crank to "sag". That is, the crank is allowed to move slightly up and down and this rattle or knock is what you hear as a result. It is more noticeable at lower engine speeds in every motor I have ever seen it in. I have replaced the crank bearings in many units and it solves the problem perfectly. I bought my bearings at a bearing supply house - costs less than $20 for both. I have no doubt that this is your problem - now for my opinion and suggestion. You are running too lean of an oil/fuel ratio. You need to run at 50:1 or 40:1. You are starving your bearings for oil causing this problem. Simply run Echo, Stihl, Exxon or some other normally priced, quality oil. THIS IS YOUR PROBLEM. I have seen it too many times. 100:1 won't cut it whether it's Amsoil of any other brand. These 2-stroke Suzuki's are very well built and will not give this problem if it wasn't for the operator neglecting them. Forget blaming Suzuki for buiding a sub-standerd engine - they did not. It simply needs the proper oil mixture.

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