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  1. #1

    Join Date
    May 2011
    Posts
    4
    Location
    North Carolina
    Mower
    John Deere

    JD GT-235 / B&S motor running rich

    Girlfriend has an older model John Deere GT 235 lawn tractor with the Briggs and Stratton engine.

    The engine has started sucking oil into the air cleaner can, (Vent tube runs into the air cleaner next to the carburetor), soaking the air filter element, and causing the engine to choke itself and die.

    I figure that there must be an air inlet valve of some sort, venting the crankcase, in another location that has become clogged allowing the air cleaner vent tube to suck oil.

    When I remove the air cleaner, the engine runs fine and seems to have full power, and so I am thinking that the motor is not seriously damaged.

    If I am correct in assuming that there is another vent which may be clogged, I'd like to learn where to look for that vent and how to go about cleaning or replacing it.

    Thanks for any help you folks can provide.

    John

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  3. #2

    Join Date
    May 2010
    Posts
    5,446
    Location
    Kansas, Butler county, Just east of DooDah
    Mower
    CTL

    Re: JD GT-235 / B&S motor running rich

    John ... Welcome to LMF...
    Check the carb to see that it is not in fact running fuel into the engine , washing the cylinder wall and ending in the oil... this will over a short time do a lot that will lead to big problems...
    Over fills the oil.
    Thins the oil allowing it to easily blow out the crankcase vent... (there is only that one)
    reduces the lube at the rings causing excess blow by.

    You might switch to a heavier engine oil to get a little more life from that engine, but if the rings are bad, it will not help a lot...
    If you can check the compression... KennyV

    PS...
    As far as you know... did this engine get regular oil changes?

  4. #3

    Join Date
    May 2011
    Posts
    4
    Location
    North Carolina
    Mower
    John Deere

    Re: JD GT-235 / B&S motor running rich

    Quote Originally Posted by KennyV View Post
    John ... Welcome to LMF...
    Check the carb to see that it is not in fact running fuel into the engine , washing the cylinder wall and ending in the oil... this will over a short time do a lot that will lead to big problems...
    Over fills the oil.
    Thins the oil allowing it to easily blow out the crankcase vent... (there is only that one)
    reduces the lube at the rings causing excess blow by.

    You might switch to a heavier engine oil to get a little more life from that engine, but if the rings are bad, it will not help a lot...
    If you can check the compression... KennyV

    PS...
    As far as you know... did this engine get regular oil changes?
    Hey KennyV,

    Thanks for the welcome and advise. The GT235 has been maintained regularly and has been owned by my girlfriend and her family from day one.

    Oil & oil filter, and air filter were changed several weeks ago, (By G.F.'s son in law, who is competent for that job), not sure what weight oil was used. The machine has seen approx. 5 hours service since that service was done. Son in law was mowing with the machine when the problem started. She started losing power, sputtering, and blowing black smoke. Son in law drove her to the barn, (Approx. a third of a mile), and parked it.

    When I first looked at the tractor after the problem started, I started the motor. It stumbled quite a bit and was blowing black smoke. I shut her off and removed the air cleaner cover and filter. The filter was wet with oil and the engine side of the air filter can, and the intake horn of the carb was wet with oil. I restarted the motor without the air filter and she ran clean, (No black smoke, and smooth running). I drove it around enough to determine that she seems to have her normal power. It looks to me like the vacuum created in the air filter box, (When assembled), is sucking oil through the tube, (Crankcase ventilator?), that ends in the air filter can. Is the oil fill cap / dipstick vented? I'll have to look at that this weekend.

    I checked the oil and it is clean and looks like oil, (Not thin and or watery, and didn't smell of gasoline).

    The oil level was down halfway between full and fill on the dipstick. This motor has not used a lot of oil in the past and it was filled properly, (I checked it after the Son in law changed it), a couple weeks ago.

    I will check compression this Saturday.

    Thanks again for your welcome and help, KennyV. Wish me luck.

  5. #4

    Join Date
    Aug 2011
    Posts
    3
    Location
    New York
    Mower
    White

    Re: JD GT-235 / B&S motor running rich

    Hi i have a similar problem with a white gt 2550. 25hp B&S . i changed the oil with 5w20 semi synthetic. It was puffing smoke quite often but not always. i took off the air cleaner cover just like you did and it ran better. i then read about sticking with straight 30w oil so i changed the oil to that. this is a OHV engine so i checked the valves and they were at .015 and they are suposed t be at .004 to.006, so i set them. now i ran it some then checked the compression and that was about 140 each cylinder which i assume is good. mowed the lawn for a while and everything seemed well, even with the air filter cover on it. i did pull the plugs after that which i had just cleaned before the mowing and seen that one cylinder plug was black with carbon so i'm trying to find out how to correct that. I am writing you for a follow up on your suspicions of the breather vent. was you able to make any progress there?

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