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Cylinder coatings

Discussion in 'Mechanic and Repair' started by zmelli, Oct 13, 2012.

  1. kawakx125

    kawakx125 LawnSite Bronze Member
    Posts: 1,128

    you answered your own question, its a Kohler lol
  2. piston slapper

    piston slapper LawnSite Platinum Member
    Posts: 4,240

    Brilliant....Dont expect to see you at any update schools anytime soon....

    High concentrations of ether can affect the nickle silicone plating on the liner.
    Under combustion the ether can exploit any weakness in the plating..
  3. jkilov

    jkilov LawnSite Bronze Member
    from MS
    Posts: 1,415

    I'm no expert but here's what I know: from cheapest to most expensive:

    bare cast aluminum cylinder:
    + cheap, good heat dissipation, light, good oil adhesion, easy to re-bore,
    - soft, prone to wear from particulate matter, low durability

    "kool-bore" cast aluminum cylinder: same as above but with etched bore for somewhat improved durability (still poor)

    cast aluminum cylinder with dry iron liner:
    + very good compromise, light, relatively cheap, good oil adhesion, can be re-bored
    - thermal conductivity and expansion at joint: goes out-of-round when overheated

    cast aluminum cylinder with wet iron sleeve:
    + good compromise, relatively cheap, good oil adhesion, sleeve can be replaced
    - sleeve likes to move, sealing problems

    cast iron cylinder:
    + very tough and durable, material flaws hardly present, endlessly renewable
    - heavy, outside rusts, more expensive to cast (small engines), long warm-up

    cold-forged aluminum cylinder:
    + somewhat harder than bare Al, even lighter, compatible with forged pistons
    - rarely done, expensive, not much better wear unless coated

    chrome plated aluminum cylinder:
    + hard, low wear, light, good heat dissipation, oxidation immune
    - poor oil adhesion - usually airborne lubrication, rarely repairable

    Nikasil plated aluminum cylinder (nickel aluminum silicate carbide) ? or something ...
    + low wear, light, good heat dissipation, good oil adhesion
    - prone to sulfur degradation (poor quality fuel), not repairable (throw-away)

    A whole bunch of other liners exist, but that's how far I can reach.
  4. kawakx125

    kawakx125 LawnSite Bronze Member
    Posts: 1,128

    If my memory serves me correctly from my dirtbiking days you CAN have nikasil cylinders replated...
  5. jkilov

    jkilov LawnSite Bronze Member
    from MS
    Posts: 1,415

    I'm sure it can, but like so many things today I'm talking about what is economically sensible. Sending a worn cylinder back to OEM for re-plating probably isn't.
  6. kawakx125

    kawakx125 LawnSite Bronze Member
    Posts: 1,128

    sorry i just can't resist...ether eats up plating, well a Kohler probably needs lots of ether to start!
  7. piston slapper

    piston slapper LawnSite Platinum Member
    Posts: 4,240

    I'm gonna go out on a limb here and guess...
    Your mommy and daddy left you home alone tonite and you found out how to turn on the computer....

    Some of us find this forum educational and some of us take time out our busy schedules to help those who otherwise would be at the mercy of the repair shops....and then there's people like you...

    Plating issues are rare ....which makes diagnosing them all the more difficult..
    I came across 3 or 4 engines about 10 years ago with plating scarred so bad that it was amazing that they even ran...Kohler was not aware of any issues with their engines and had us send them back to the factory..after talking with the owners of the engines..the only common denominator was the use of ether..
    Which under lab conditions recreated the condition....

    Posted via Mobile Device
  8. kawakx125

    kawakx125 LawnSite Bronze Member
    Posts: 1,128

    lighten up there buddy, seems to me in the first place that this thread's originator already answered all of his own questions via google.

    i've had poor experiences with kohler engines, i'd never buy anything with one on them and there's alot of people on here that feel the same way.

    as far as plating issues go lots of things can cause it. oil starvation, worn piston, rings, improper honing, dirt ingestion. kohler specifically states NOT to hone their cylinders. i've seen other engines be rebuilt with less than perfect cylinder coatings and run like a top for a long time
  9. piston slapper

    piston slapper LawnSite Platinum Member
    Posts: 4,240

    Sorry about that chief...couldn't help myself...
    Incedentally I have the proper hone and have been deglazing (crosshatching) the nickle silicone bores for more than 10 years...the key is to know when and how to use it...
    The plating is only bout .010 thick...if there are any dull whitish areas in the cylinder...these are thin spots...a good reason to leave the hone in the toolbox.
    Posted via Mobile Device
  10. BigFish

    BigFish LawnSite Gold Member
    Posts: 3,253

    Where'd you come up with that at??? First I've heard of that!

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