gravely cool down confusion

Discussion in 'Lawn Mowing' started by slowleak, Apr 8, 2003.

  1. slowleak

    slowleak LawnSite Member
    from 63055
    Messages: 96

    any body out there own a gravely.? just bought a 260z w/the kohler command 25. my dealer drops it off and goes through his delivery spiel and says" now this may sound wierd but,you need to rev the motor UP before you shut down". now this goes against everything i've been taught. ya know,"cool down time" anyone ever hear this before.? maybe because of backfire.?
  2. Green Pastures

    Green Pastures LawnSite Silver Member
    Messages: 2,457

    Sounds weird to me, but then again I'd do whatever I read in the manual, not what a dealer told me. I want to read it in black and white.
  3. Gravely_Man

    Gravely_Man LawnSite Silver Member
    Messages: 2,075

    would call Gravely tech support, as I have never heard of this procedure before. I would agree with letting the engine idle for a few moments prior to shutting it down. If taken to extremes and you rev the motor up and shut it right down the chances of unburned fuel sitting in the cylinder is quite high. This can then leak past the rings and get into the engine oil. Please let us know what you find out.

  4. slowleak

    slowleak LawnSite Member
    from 63055
    Messages: 96

    i have just called (2) two dealer service people in the st.l. area. and yes,that is what i'm supposed to do. although this goes against what the owners manual says. but i'm going to do some more digging on this subject.
  5. Jman

    Jman LawnSite Member
    Messages: 217

    Well look at it this way, what cools an AIR cooled engine. The fan blows the air across the engine, when you slow the engine down do you blow more air or less air? When the engine is running wide open the throttle is actually barely open. There is a governor there. One way I like to look is to compare it to what you would do to your own vehicle. Would you pull into your driveway after going 200 miles in your $35,000 truck, get out , drain half of the antifreeze out of the radiator and let it sit and idle to cool down??? The other reason to let it run wide open is to prevent it from afterfire when you shut it off. The fuel shut off solenoid in the carb only shuts off the high speed jet in the carb, the idle jet still flows fuel.
  6. Cut This!

    Cut This! LawnSite Member
    Messages: 48

    I'm pretty sure it's good.

    The backfire is caused by raw gas leaving the cylinder and entering hot muffler. Kohler has installed a "fuel shut-off" solenoid on the engine that is a tiny plunger that shuts off this flow of fuel. But the solenoid only works when the engine RPM is high enough to activate it.

    There fore the dealer is recommending you rev the engine to cause the fuel shut-off to engage and keep fuel from entering the muffler.

    I think you could lower the RPM to let the engine cool, then rev it just before shut-off to engage the fuel shut-off.

    By the way, the backfire is enough to scare the *((&^^)& out of you - especially in an enclosed space.
  7. slowleak

    slowleak LawnSite Member
    from 63055
    Messages: 96

    yeah i know about the backfire.a guy i worked with had bobcat with the 25 kohler. his would backfire all the time on shut-down. we cut on some country club property and one time we shut down to have some coffee. his went BOOM and we had calls from the hoity toity residents to the general mgr about someone "firing a gun" :D . this also led(his bobcat backfiring) to numerous trips to the dealer. they'd have it 2wks at a time......
  8. Craig Orth

    Craig Orth LawnSite Member
    Messages: 5

    the dealer is correct when he told you to shut the engine down by first throttling it up. I double checked this with our engineering staff as well as going to Kohler's website to verify it. The owners manuals on the website state the following.

    For engines equipped with a shutdown solenoid: Position the throttle control somewhere between half and full throttle; then stop the engine.

  9. TLS

    TLS LawnSite Fanatic
    Messages: 7,943

    You guys are correct.

    I let mine idle (fast idle 1750 rpm) for a few minutes as I strap down the mower on the trailer, then I raise the throttle to 1/2 as I switch off the key. Stopped it alltogether! Remember I run a Liquid Cooled engine.

    My Little Wonder cant do this, as the throttle is the ignition cut off. It is almost guaranteed to leave a backfire with actual FIRE!!! A 6" flame pops out the muffler when it backfires!!! Wicked cool man!

  10. Green Pastures

    Green Pastures LawnSite Silver Member
    Messages: 2,457

    I would NEVER do something contrary to what the supplied owners manual says.

    If these "dealer service people" are willing to put what they're telling you IN WRITING and then IN WRITING guarantee the mower, then I would follow their advice. If not, I'd do what the supplied owners manual says.


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