3.5 Briggs could it be the valves ?

Discussion in 'Mechanic and Repair' started by Bunton Guy, Sep 15, 2001.

  1. Bunton Guy

    Bunton Guy LawnSite Bronze Member
    Posts: 1,746

    I have a 3.5 B & S motor on my 20-21" push mower its made by Yard Machine...I use it on yards that I cant get in there gates with a 36" Its been used commercially 5-6 times a week for 2 years now...the problem is everyonce in a while it will make a weird noise its hard to describe..its kina like the sound of when you shut a door..(not to hard) could that be the valves or the ignition timing off ? Its not that big of a deal the performance hasent gone down and if I loose the motor I could care less..I just bought the smallest and lighest mower I could find got it new at Lowe's for 99 bucks. Also how do you guys feel about the 25 HP Kohler motors ? are they strong running Im looking into getting one that is on the Great Dane Chariot or Hustler Z.
     
  2. Fish

    Fish LawnSite Member
    Posts: 139

    Are you talking about a squeal or a clunk?
    Fish
     
  3. khouse

    khouse LawnSite Bronze Member
    Posts: 1,465

    It's hard to tell from here. It could be a lazy valve which is slow to close sometimes due to a gummy guide. It could be the coil module assembly if yours is equipted with a magnatron ignition. It is one of those things that can't be replicated at will and is very hard to figure out. I would suggest running it untill the problem gets worse and is easier to figure out. But for the cost of a 3.5 briggs just buy a new one.
     
  4. Bunton Guy

    Bunton Guy LawnSite Bronze Member
    Posts: 1,746

    Yeah I know...like I said. I could care less if the motor bombs on me. I had gotten my moneys worth out of it 10X over. Its like you guys said a " Clunk" and I would say yes that best describes it. Thats about the only noise I can say it sounds like is a clunk. What does that mean ?
     
  5. Robert Doubrava

    Robert Doubrava LawnSite Senior Member
    Posts: 342

    what's the model, type, and code? the code really doesnot matter, it just tells you when the engine was made. i learned that from the briggs and stratton website. the address, if you dont know it, is http://www.briggsandstratton.com

    1. the first two numbers tell you what year it was made.
    2.the second two tell you what month.
    3. the third two tell you what day of the month.
    4. the last two tell you what assembly line and manufacturing plant it was made at. for example, the numbers on my rider's engine read,
    model:170702
    type:1517
    code:80032709 :blob3:
     
  6. Robert Doubrava

    Robert Doubrava LawnSite Senior Member
    Posts: 342

    i think it could be the rod hitting the side of the crankcase. my dad said that may be the cause of the noise. what that means is that the engine is probably going to throw the rod. :eek:
     
  7. vipermanz

    vipermanz LawnSite Bronze Member
    Posts: 1,773

    loose connecting rod/wristpin?
     
  8. khouse

    khouse LawnSite Bronze Member
    Posts: 1,465

    I don't think it's a major engine problem now. If it was it would be a rhythmic sound. Since it comes and goes at random I think it may be the metal deck flexing back and touching the blade. Maybe it's something besides the engine. Just another thought.
     
  9. vipermanz

    vipermanz LawnSite Bronze Member
    Posts: 1,773

    not to make you feel dumb but,, could it be a motor mount?
     
  10. Robert Doubrava

    Robert Doubrava LawnSite Senior Member
    Posts: 342

    like vioermanz said, it could be the motor mount. check the bolts holding the engine to the mower deck.
     

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