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Sucked up some plastic...now PTO will not engage

Discussion in 'Mechanic and Repair' started by apache, Jul 23, 2013.

  1. apache

    apache LawnSite Member
    from md
    Messages: 23

    My Scag walk-behind, pull start older model sucked up a piece of plastic the other day while cutting & has trouble engaging the blades at full throttle continuous. When it sucked the plastic I had to turn the mower off & remove the blades to take out all of the plastic because it melted on the blades. Once reassembled the PTO would engage as normal then it took about a minute vs. instantly when it decided to engage the blades. When it came in contact with grass to cut the PTO would disengage itself (sounding like it just died) & when brought back to lower already cut grassy area it would reengage itself.

    It is unable to cut any grass & has difficulty automatically engaging.

    I also noticed that one of the wires going to the PTO switch was severely charred as if it was over heating. But also that might have been a problem prior. I'm wondering if the PTO clutch is toast/weakened by the plastic that I sucked in which might have caused the system to overproduce current.

    My mower is out of service now. If someone has any suggestions it would be very helpful?

    Thank you
  2. monoshock

    monoshock LawnSite Bronze Member
    Messages: 1,325

    Sounds like the clutch is burnt, might as well plan on a new one.
    If you install a new one yourself make sure to burnish it.(break it in)
  3. CorkyE

    CorkyE LawnSite Member
    Messages: 124

    Replace the burnt wire first and check for 12 volts to the clutch. If you're getting proper voltage to the clutch, I agree that it's probably toast.
  4. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,335

    Remove the blade belt and make sure the spindles spin freely..
    Repair the charred clutch wire..
    Adjust the clutch....it may have worn a little when the blades sucked up the plastic..
    Search this forum for clutch adjustment procedures..
  5. apache

    apache LawnSite Member
    from md
    Messages: 23

    Everyone your responses are quite helpful... I'll try them asap.

    Thank you very much!!

    I've been getting slammed with other items but I have to fix this asap ... the grass has been growing & it won't cut itself!
  6. apache

    apache LawnSite Member
    from md
    Messages: 23

    Ok this is where I'm at:

    I repaired the burnt wire & cleaned off the burnt corrosion off the pto prong as well. Then, I removed the blade, loosened the belt and made sure the spindles spun freely & also cleaned everything under the deck.

    I noticed that some of the nuts for the air gaps were at different lengths, tried to eyeball them but I think I need to get a feeler gauge to get proper adjustments. I then moved on to checking the volts to the clutch (which was the three wire clip, which ran on top of the deck going to the clutch which I disconnected). It measured between 13.50-13.80 DCV. I looked up the Warner MagStop Clutch/Brake Electrical Evaluation & said Voltage should be 12-14 volts DC. The actual clutch wire was left dangling while the mower was running.

    My next moves are:
    1. Try to get the exact air gap adjustment –which I believe is around 12000?
    2. Clean off the PTO switch again– which has built up more burnt corrosion in the one contact? Same contact that burnt prior.
    Don’t know what’s going on there?

    During the eyeball air gap adjusting some of the adjustments did nothing & other made the pto power on gradually. When it did power on I made a test cut on some grass & it died out when it came in contact with high grass.

    What are some other suggestions thoughts on what’s going on?

  7. apache

    apache LawnSite Member
    from md
    Messages: 23

    Also, while going to clean the pto prong again there is 2 wire now burnt (the yellow & blue wire). The yellow wire was actually producing smoke.

    Both prongs are now burnt but don't know what's causing it?:confused::confused:

    I haven't been out to get a feeler gauge yet!
  8. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,335

    Get a multimeter...check for continuity between the wires and the outside of the clutch..
    There should be none...if there is..1 of the wires is grounded to the case..thats bad...
    If so ..strip back the wires and see if you can isolate and repair the wires..
  9. apache

    apache LawnSite Member
    from md
    Messages: 23

    Update :Thanks for everyone's replies. Yes there were some corroded wires & the Pto clutch was toast.

    New problem: I replaced the clutch today, buttoned everyone thing together & getting ready to burnish the pto clutch. As I started it & every time I switch the pto switch The blades moves but the motor immediately dies when engaging blades. It doesn't even get into that loud whine sounds when the pto is engaged.
    Would anyone have any suggestions?
  10. BigFish

    BigFish LawnSite Platinum Member
    Messages: 4,158

    Sounds like you need to replace the PTO switch. Could also be one of the safeties, but you said the PTO switch terminals were burnt, etc., time for a new switch, no?

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