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Engine knocking..

Discussion in 'Mechanic and Repair' started by hoylebros, Sep 30, 2009.

  1. hoylebros

    hoylebros LawnSite Member
    Posts: 100

    I have a Toro 60'' with a 27HP Kohler engine. The thing runs great and starts every time but, probably 9 times out of 10 when I shut the engine off it will knock really bad and/or backfire. Has anyone had this problem before or maybe knows what the problem is...Engine has 500hrs on it. Thanks guys!
  2. Two Seasons

    Two Seasons LawnSite Senior Member
    Posts: 791

    We have the same engine on our Turf Tiger.

    We let it idle for about 30 seconds before shutting it down. No problems with doing it this way.
  3. jvanvliet

    jvanvliet LawnSite Gold Member
    Posts: 3,939

    Have X-Mark Lazer Z with 27hp Kohler. Had same problem with engine knock after shutting down. Since I run it for 4 to 6 hours straight in the Florida heat, I throttle down real slow and let idle for about 2 minutes or so while my men blow off the mower and I swill large quantities of Gatorade. Works great. You'll get a sense of timing with experimentation for your machine. Some guys idle for a few seconds, others for a few minutes. Do what works for you!
  4. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,023

    Some will chime in and say the manual states to shut down at 3/4 or higher throttle setting. Well, As said it's what ever works for you. I don't start a engine at 3/4 or do I shut one off at 3/4, A few second cool down works fine. Again..... It's what works for you.
  5. jvanvliet

    jvanvliet LawnSite Gold Member
    Posts: 3,939

    Shutting down at anything significantly more than idle produces engine knock in my machine. I use medium grade gasoline so I don't think it's the low octane rhumba. Whatever causes it, I cure it by idling down slowly and letting the engine run at low idle for a couple of minutes. There's lot's of things in books and manuals that contradict practical experience in the field. Knocking is the spark plug firing on an empty chamber... right? I don't think that's good for the engine. Since the guy who wrote the manual is not out in the field... as Frank Sinatra said "I do it my way".

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