Gas in oil

My 300 has less than 300 hrs on it's overhaul.(pistons,sleeves,rings,bearings) tractor runs limited time on a rotary brush cutter and snowblower in the winter.i have not used it in probably a month and a half. Just pulled the dipstick and oil is over full and smells gassy. I have the main fuel adjustment screw turned out to the maximum power setting (5 turns) according to the IT manual I have. Would this somehow cause excess gas in the oil ? When cutting and blowing snow I run it wide open and the tractor is working pretty hard. I do not shut the gas off at the sediment bowl when not in use. It runs and starts perfect. Should I back off on the fuel adjustment some ? Tractor does not smoke at all when idling or working hard. I changed the oil several times since the rebuild just to be safe and had not really noticed the oil level coming up probably because of the low hours between changes. Thoughts ?

Your problem is you do not shut off the gas at the sediment bowl when not using it. Gas can/will seep past the float needle and then fill carb to the point of over flowing and then seeps into the engine and then into the oil. Did some work on an old Ford 9N and I drained out 5 gal of gas and oil mix due to the guy not shutting off the gas at the sediment bowl

Old would the gas be getting in through the governor or getting so high that it is going through the intake ? I haven't noticed any seepage anywhere.

Gas tends to go to a vapor then condenses in the cylinders and slowly leaks down the sides of the pistons. At least on most. It can also get in by way of the governor on those IH set ups. I always turn off the gas on 99% of my tractor due to the gas in oil problem and it can be one of those things that it does not do it today but sooner or latter it will on most any tractor engine

I have seen them fill the manifold and run in through the valves hydro locking a cylinder. It can get in through the throttle shaft, but slower. Just shut off the fuel. It is Standard operating procedure and in the manual. Changing the oil is more costly and takes more time than shutting off the valve. Jim

Ok Jim I will.switch my habits !

Yeah I will do that from now on. Never had it happen before since I owned it ( 10 or 12 years). Guess I should start ! Thanks !

Yep I too in the past did not shut off the gas on my tractor till one day I found gas in the oil and if run that way it can end up with a blown engine real fast

If it is any help, there are electric fuel shut off valves, that can be installed in your fuel line. Pretty handy.

While fixing make sure the filter material and hole in lower bowl will let overflow gas drain. Unless you have a needle and seat passing enough gas to keep tractor from running okay it should pass enough to keep gas from going in the engine.

Yep, back in the 1960's and '70s we never shut the gas off on anything, except motorcycles. Then it seemed like without warning the gas tanks were always empty when we needed a tractor. Now everything gets the gas turned off as soon as it's shut off.

Two things I would suggest. Pull the coil wire out of the distributor and ground it to some part of the engine. Then pull the choke fully shut and crank the engine 3 seconds. Then wait 30 seconds or so, the carb should start to drip gas from the bottom just ahead of where the air intake hose fits on it. That should put enough fuel in the lower air inlet section of the carb to test the drain D Slater is referring to. If it does not start to drip in 30 seconds or so you need to figure out why. When that works properly it should not let enough gas buildup in the carb/intake to let it get into the oil through whatever path. If enough is getting through to flood into the engine you will see enough of a drip pool where it is parked to alert you of the problem. Secondly, you should check your hydraulic fluid level, it is possible the hyd. pump seal has started leaking and that is what is raising the engine oil level and the oil just naturally smells gassy. Not saying that shutting the gas off is a good practice, but I was never taught to do it. This was from me growing up on a farm in KS where we had 2 Hs, M, 300, 350 and for a time a 656. We never practiced turning off the gas. Of course generally each one would get used at least once a week. However, once in a while one could set 2-3 months without use and we never had any serious problems. Good luck!

One thing I should add to the ?over choke? test. After the cranking push the choke back in. In the case you have a choke plate that seals exceptionally well it may not let the gas flow past it back to the area of the drain.