28 Kohler

Discussion in 'Lawn Mowing' started by Imow4u2, Jun 16, 2007.

  1. Imow4u2

    Imow4u2 LawnSite Senior Member
    Messages: 377

    Just over 400 hrs. on my E.F.I. and around 30 hrs. on service it we be down to the add mark.. Any ideas, this just showed up in the last 150 or so hrs.
  2. tacoma200

    tacoma200 LawnSite Fanatic
    Messages: 5,426

    I forget how much oil it takes to fill it from the add mark. That will give us an idea how much it is using in a 30 hr period.
  3. Mark

    Mark LawnSite Senior Member
    Messages: 723

    :usflag: Your engine should not be burning any oil with so little hrs, Ive got a 28 with 2200hrs and it don't use enough to where i can see it on the stick...Should be under warranty...Id let the dealer take a look at it......Do you see any smoke or oil speckles,and maybe the filter is leaking very slowly, but you should see that and oily lines...Something is wrong ........Marks Mowing Service
  4. Richard Martin

    Richard Martin LawnSite Fanatic
    Messages: 14,699

    How many RPM you turning? My 28 EFI becomes a pig for oil much above 3700.
  5. puppypaws

    puppypaws LawnSite Fanatic
    Messages: 9,177

    Why would you think only 100 more rpm's would make that much difference in oil consumption?
  6. Richard Martin

    Richard Martin LawnSite Fanatic
    Messages: 14,699

    I'm not entirely sure. It could be cylinder pressure or vacuum. My Kohler 25 used to use a lot of oil and it popped head gaskets about every 400 hours when I had it set to 3750 with the blades on. I even put a new head on it to no avail. Once I slowed the RPM down about 100/150 the problem went away. When I bought my 28 EFI it was set to 3800 no load and 3750 with blades on. Right away at 29 hours it was already using oil so I dropped the RPM to 3650 with the blades on and I haven't had to add oil even at a 50 hour OCI.
  7. puppypaws

    puppypaws LawnSite Fanatic
    Messages: 9,177

    I sure appreciate you talking with me about this. I checked the rpm's on mine when it was delivered and it was at 3600 no load, when I checked it a couple of weeks ago it was at 3550 at 225 hrs. I called a Kohler design engineer I kinda became friends with over time and asked him what rpm's could be run on the 28 efi without problems. He said the engine is set up for 3750 on the top end at no load. I said, ok what you are telling me is I can set mine at 3750 no load and will not have to worry about any problems, he said, that is correct.

    Now the real life experience you are having is telling a completely different story, it seems to hurt the engine at their recommended rpm setting.

    He told me Exmark had factory set their mowers with the 28 efi at 3750, is this true, I really don't know.

    I wonder if we would get any input from other owners on this subject if it was in a new thread?

    I ran the fool out of mine yesterday and the oil was good when I started. I will see if there is any difference when I check it today. I have only put about 15 hrs. on the mower since I jacked the rpm's up so it may not be ready to show up yet.
  8. Richard Martin

    Richard Martin LawnSite Fanatic
    Messages: 14,699

    Some people have problems at high RPM settings and some don't. I can't explain it and quite frankly, don't care since there's nothing I can do about it. I lower my RPM and it doesn't use oil, I raise RPM and it blows head gaskets and uses oil.

    It's just like that thread about what RPM to shut an engine off at. When I shut my engines off at high RPM I get a big cloud of oil smoke when I start them up again. If I let them sit and idle for a minute or two I don't get a cloud of smoke. I can also hear internal parts ticking as they contract from the heat (from cooling off) if I let them sit and idle. I'm going to pick up one of those infrared thermometers and see exactly what is going on. I know the engineers say they cool better at high RPM but those are the same kind of people who designed the first 2 space shuttles that blew up. Design and actual function may be different, you know what I mean?
  9. Richard Martin

    Richard Martin LawnSite Fanatic
    Messages: 14,699

    See, now you've made me think about this...

    It may simply be a solution as simple as a better head gasket. Kohler uses a graphite based head gasket and it simply may not be up to the job at high RPM. They use a graphite gasket since they are more forgiving on precise torque values and don't require retorqueing or a perfectly flat surface to seal. A better metal based gasket would probably cure the problem.
  10. puppypaws

    puppypaws LawnSite Fanatic
    Messages: 9,177

    I sure am glad you got on this subject, I checked my oil this morning after running hard yesterday and it is almost down to the add mark. I have never seen the oil go down in this engine enough to hardly notice and by raising the rpm's 150 or so the oil consumption went up tremendously. I had not run the mower as hard continuously as I did yesterday and it sucked up some oil.

    What rpm was the maximum you found at no load the oil consumption stopped? I will talk with the Kohler engineer about this but what you said about the space shuttle is true.

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