20 hp kohler magnum with burnt valve

Discussion in 'Lawn Mowing' started by LawnMastersTN, Jul 21, 2012.

  1. LawnMastersTN

    LawnMastersTN LawnSite Senior Member
    Posts: 273

    Looking at a mower with a 20hp kohler magnum but it has a burnt left side value. Need someone who knows about these engines to tell me if its worth fixing. I know my 61 turf tiger with the 25 hp kohler has head gasket issues but they are easy to fix as I have done it twice. Anybody have an opinion?
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  2. LawnMastersTN

    LawnMastersTN LawnSite Senior Member
    Posts: 273

    anyone have any ideas?
     
  3. Richard Martin

    Richard Martin LawnSite Fanatic
    Posts: 14,700

    Assembled Kohler heads aren't expensive. I bought one to fix a chronic blown head gasket problem. It was for a 25 and was under $100.
     
  4. Richard Martin

    Richard Martin LawnSite Fanatic
    Posts: 14,700

    On your 25 with the head gasket issues... What RPM is it running at with wide open throttle?
     
  5. LawnMastersTN

    LawnMastersTN LawnSite Senior Member
    Posts: 273

    I'm really just wondering about the 20 hp magnum. My turf tiger with the 25 command has over 1800 hours so a $15 head gasket fix isn't bad. But I need to know can't the magnum. Guy says burnt valve
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  6. Richard Martin

    Richard Martin LawnSite Fanatic
    Posts: 14,700

    Fix it. Like I said, the assembled heads are relatively cheap.
     
  7. LawnMastersTN

    LawnMastersTN LawnSite Senior Member
    Posts: 273

    Oh i just realized I should've been more specific. I need help with diagnosing it. They guy seems not to know anything about engines really.
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  8. PabsMaster

    PabsMaster LawnSite Member
    Posts: 119

    I agree, its worth fixing.
     
  9. Richard Martin

    Richard Martin LawnSite Fanatic
    Posts: 14,700

    You can put a vacuum gauge on the engine while it's idling and the needle will bounce moderately. If there is nowhere to attach a vacuum gauge then you can do a leak down test. The cylinder with the bad valve will leak down faster and lower than the good cylinder.
     
  10. herler

    herler LawnSite Fanatic
    Posts: 5,144

    I don't see how we can possibly know what is wrong with that engine from our perspective, we have as much information as you do, burnt valve, I can tell you from my experience it's easy and cheap enough to replace just the valve IF that's all that is wrong with it but I have no way to know without taking a look at the actual engine and even then you may just have to bite the bullet and take a chance but if you want to play it safe then don't buy it.

    On another note, replacing a valve can test even the experienced mechanic, but once you know the trick it is relatively easy, unfortunately the trick varies from one engine to the next, which is why they sell fully assembled cylinder heads...

    An assembled head run you about $100 or so, you have to know how to replace THAT if you plan on having a running 20hp.
     
    Last edited: Jul 23, 2012

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