John Deer M gas in oil

Dim Pete · Jun 5, 2018

Hi, I bought a 1948 M from my neighbor before he died. The M has always run great. This year after sat all winter (with the gas shut off) I ran it for about 1/2 hour and later checked the oil, it was way over the full mark. I drained it and it smelled like gas. I assume it was the carb so I put in a new needle and seat under the float. The float seemed fine. I put the carb back on and started it briefly. Was I correct in assuming the carb was the cause of the gas in the oil, or am I missing something else. How do I know it will not happen again. Thanks for any help

Hayfarmer · Jun 5, 2018

I think your assumption was right. generally if the engine is running ok you won't get gas in the oil until you stop it and let it sit. At one time my 430 was missing on one cylinder but I ran it to do some small job. Since it was still pulling in fuel on the other cylinder I got the extra in my oil.

golfcartman · Jun 5, 2018

Your tractor has a updraft carb. so it would be leaking really bad to get in the engine, but that about the only way it could get there. You need a good cut off valve between the tank and carb. And make sure it cuts off completely. Drain the carb after you cut the fuel off and check the next day and see if you have fuel in the carb. If so its not cutting off good.

M-MAN · Jun 5, 2018

If you don't want it to happen again just go to roberts carb site and purchase a new sintered bronze weep plug that goes in the bottom. A small pin punch will knock it out and a larger one will knock it in. When you do that any time gas gets by the needle and seat it will drip to the ground.

Dim Pete · Jun 6, 2018

It seems to be running well on both cylinders, so I do not think it is a missfire. I will look into replacing the weep plug. I know the shutoff works well because I used it to when I took the carb off. thanks.

Hotflashjr · Jun 6, 2018

I would keep an eye on the float. My MT did this and the float had a pin hole for 1 and wasn't set well for 2. I would get fuel into the air cleaner connecting tube when the tractor wasn't running if the fuel was left on. Then, on starting it would suck it into the engine and also had a fuel smell in the oil. A new float cured my issue and I also replaced the weep plug that M-Man talks about at the same time.

Dim Pete · Jun 6, 2018

Air cleaner did not seem to have any fuel in it. Float seemed good, but maybe it is not sitting well. I will get a weep plug.

Jimmydog · Jun 6, 2018

Having similar trouble with my "new" JD model B. The shut off on the sediment bowl didn't work when I bought it, so just to get by on for a while I put a cheapy shut off valve in line. That seemed to fix things until we ran it hard for a couple hours and it died. Cylinders washed, gas in the crank again. Turns out that while driving the carb was running so rich that it was blowing past the rings. The nephew said he could smell gas and he just thought it was supposed to make white smoke. In his defense, he's a newly minted ing-ga-neer. Yep BME and all. It appears that who ever had the machine before me had made their own carb adjustments and the load screw was out about 3&3/4 turns and the idle was out 4 plus. I don't know what's about normal for these but I doubt it's that much. If any body knows where theirs' are roughly set at I'd be glad to hear from you. I'll be ordering a rebuild kit and new sediment bowl in a couple days.

Oh yeah, and he made a mess of the brush hog. Darn kid that's what chainsaws are for!

JD

Dim Pete · Jun 7, 2018

Took the carb off and the weep plug is either missing or has been drilled out. I also noticed the L shaped fuel needle was way loose. The brown packing material was pretty much disintegrated. Could either of these things be the cause of the gas in the oil? I ordered new parts from Roberts.

John Deer M gas in oil

Dim Pete

Member

Hayfarmer

Well-known Member

golfcartman

Member

M-MAN

Well-known Member

Dim Pete

Member

Hotflashjr

Well-known Member

Dim Pete

Member

Jimmydog

Member

Dim Pete

Member

Similar threads