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Gas in oil

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robert

04-24-2003 18:56:06




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I carelessly left the choke slightly open on my old John Deere 40. Engine oil is now thoroughly diluted with gas. I intend to drain the oil and replace, change the oil filter, and clean or replace the spark plugs (just while I am at it and to make sure everything works well when I fire it up again). (And will keep the choke closed from now on.) Is this a reasonable correction for the situation? Obviously I am not a mechanic.

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Clooney

04-25-2003 05:43:55




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 Re: Gas in oil in reply to robert, 04-24-2003 18:56:06  
Robert, because of the design of the Dubuque 40 engine your whole carb, manifold, & intake would have to fill with gasoline before it could enter the crankcase that way.
~If your engine crankcase & oil is diluted with gasoline I would think it came from either a mis firing spark plug [cylinder misfiring] , or overly rich mixture. If you left the choke on like you thought, that would account for a rich mixture, but would also mean you didn�t get that much fuel in the crankcase. ~A good oil drain with a fresh filter installation [don�t forget to make sure the M-88 washer is still under the oil filter] would be all that�s required.
~If the dilution came from a misfiring spark plug post back for ways to diagnose that problem��.

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David Bacon

04-24-2003 20:47:57




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 Re: Gas in oil in reply to robert, 04-24-2003 18:56:06  
If you clean up everything and nothing is obvious check the oil every day. Drain off a tablespoon full in a small coffee can lid or something shallow and hold a match into it. Oil will not accelerate your flame, gas will---Common sense says no more than a tablespoon full taken outside to check it out. Good luck Dave



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JIM N,

04-24-2003 20:09:39




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 Re: Gas in oil in reply to robert, 04-24-2003 18:56:06  
Just thought I would clear up some terminology.
When you have the choke closed you are closing the choke butterfly by pulling out the choke knob. In other words, you are 'choking it' and making the fuel mixture richer. When you push the knob in you are opening the choke butterfly, so you are 'opening' the choke to make the mixture leaner. This might sound like an overly complicated explanation, but if you are trying to explain to a mechanic what you are doing, it helps to be on the same playing field word-wise. I am not real familiar with a 40, but I would't think running with the choke slightly closed would put gas in the crankcase. What does the oil smell like?

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Ralph

04-24-2003 19:33:02




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 Re: Gas in oil in reply to robert, 04-24-2003 18:56:06  
I'm not sure you would get a lot of gas in the oil unless the choke were barely open, i.e. near full choke. I'm not a mechanic either!! Check to make sure that you don't have a leaky needle valve before filling with oil. i.e. you might drain the oil, put the plug back in and check for gas a day or two later. If you do this make sure to disable the starter, i.e. disconect the battery AND take the distributor rotor to a different building to prevent inadvertent starting of the tractor.

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Ralph

04-25-2003 07:56:10




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 Re: Re: Gas in oil in reply to Ralph, 04-24-2003 19:33:02  
Oops, never thought about the 40 engine configuration, Guess I have a Waterloo brain.



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John T

04-24-2003 19:24:43




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 Re: Gas in oil in reply to robert, 04-24-2003 18:56:06  
Robert, Yep a good drain and refill and filter change should purge the gas from the oil and crankcase, (you should also take a look at the air cleaners lower oil reservoir bowl, if it has one, it may have gas in it) but Im puzzled as to how gas got there in the first place???? I alwaysssss sssss turn the fuel off on my tractors (usually at a sediment bowl shut off or an in line shut off valve) upon shut down, so in case the needle valve and seat in the carb leaks or the float fails etc, I dont drain gas into the crankcase. Regardless, if the choke were open or closed, it shouldnt over flow the carb bowl and get into the engine if your carbs needle and seat shut off is working and your float is not leaky and operating correctly. You dont mean you just ran the engine over choked and got excess gas in that way do you????? Also, does your tractor have the sediment bowl equipped with the low oil pressure safety fuel shut off???? Its the one with oil lines and diaphragms that monitors oil pressure and shuts off the gas if theres no oil pressure. If so, they can get bad with leaky rubber diaphragms which can cause oil to mix with gas.

Anyway, be sure to shut the gas off upon shut down, find out why so much gas got into your oil (carbs needle and seat, carbs float {they can leak and sink to bottom}, sediment bowl safety shut off system) and let us know.

Good Luck n God Bless, John T Nordhoff in Indiana

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robert

04-24-2003 19:45:57




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 Re: Re: Gas in oil in reply to John T, 04-24-2003 19:24:43  
Yeah, I learned the hard way a few years back always to shut off the gas. The guy who usually works on it for me said over the phone it was maybe the choke - then he went away and has been out of touch since. In desperation - it's bushhogging time - I am trying to figure what to do on my own. But maybe I'd better wait him out as I sure wouldnt know how to do anything to a carburetor. Thanks for the responses.

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Wayne in Tn.

04-24-2003 19:51:34




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 Re: Re: Re: Gas in oil in reply to robert, 04-24-2003 19:45:57  
Robert, you mentioned the tractor was a model 40. Those have an updraft carb. and there is no way gas can leak into the oil, it will just go into the breather tube or out on the ground. I don't see how running it with the choke partly out could result with gas in the oil either. Are you sure it is gas and not water? Those are noted for cracked heads.



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SamH

04-24-2003 21:03:07




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 Re: Re: Re: Re: Gas in oil in reply to Wayne in Tn., 04-24-2003 19:51:34  
Wayne, I agree. It is not unusual for the horizontal John Deeres to get gas in the oil, but I don't see how it could get into the upright 40 engine.

Robert, why don't you change the oil and filter and crank up your 40. Let it run long enough to warm up, then shut it off and see if you have the same problem. If you do, it is probably water from a blown head gasket or cracked head.



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robert

04-25-2003 07:47:29




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 Re: Re: Re: Re: Re: Gas in oil in reply to SamH, 04-24-2003 21:03:07  
Thanks to all for the helpful suggestions. First, I understand how chokes work, but have a history of saying it backwards. But beyond that, my mechanical knowledge is limited. It may very well be water rather than gas. I have no sense of smell left, so can't tell by smelling. No close neighbors and an invalid wife, so no smell assistants either. Water level in the radiator still appears normal. But you have all given me food for thought. Now I just need to sit down and think about it all and decide what to do or who to call. Thanks again. This is a most helpful group.

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Wayne in Tn.

04-25-2003 08:37:52




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 Re: Re: Re: Re: Re: Re: Gas in oil in reply to robert, 04-25-2003 07:47:29  
Robert, If there is very much water in the oil, it will turn the oil to a milky color, gas would make it thin, but not change the color much. As someone mentioned, try a match to a spoonfull, if it ignites quickly, it will be gas. But as said before, the design of the model 40 system should not permit excess gas in the oil.



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Thane

04-25-2003 09:41:44




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 Re: Re: Re: Re: Re: Re: Re: Gas in oil in reply to Wayne in Tn., 04-25-2003 08:37:52  
I have a 40W. Last year I had the oil level increase due to (I thought) gas or coolant leaking into the oil. Turns out the hydraulic pump for the touch-o-matic leaked the 10 weight hydraulic oil into the engine, since the pump is driven off of the front of the engine. I ripped off the front of the tractor, put new bearings and seals in the hydraulic pump, put everything back together, and have had no problems with the engine oil level since.

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Wayne in Tn.

04-25-2003 11:10:53




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 Re: Re: Re: Re: Re: Re: Re: Re: Gas in oil in reply to Thane, 04-25-2003 09:41:44  
Thane, yes that is another problem common to the 40-420-430 models. Those pump seals can allow hyd. oil into the engine.



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