# JD 720 with gas in oil, need new fix



## OregonJD720 (Jan 18, 2015)

OK guys. Just inherited a 1957 JD 720 gas. Grew up driving it and know my way around it pretty well. Anyway, it sat for 10 years before I got it. Got it running but ended up with lots of gas in the oil. Did the typical repairs; rebuilt sediment filter, cleaned gas shutoff valve under the tank and added a second shutoff before the sediment tank. Shut both gas valves off after shutting off last time. Ran it until it ran the carb out of gas, then dumped gas from sediment bowl. Now a month later, walked by and noticed sediment bowl is full of gas. Went to check the oil and sure enough, gas comes pouring out of the dipstick hole. Crap.. 

Anyhow, With two shutoff valves plus the automatic valve in the sediment bowl, fairly certain it's not coming in that way. Only thing I can think of is the vent line from the carb is letting gas back through. Maybe the vent tube has a hole below the gas line?? Do I need to vent the carb to the tank or can I plug the tank vent hole and run the carb vent line somewhere else.

Thanks in advance.


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## ben70b (Aug 29, 2012)

Going from memory, I put a new diaphragm in the automatic fuel shutoff on grandpa's 60. I had no gas in the oil after that. The valve opens when oil pressure is built so I'll bet you are getting fuel seeping back down one of those oil lines into the crank case. If I were in your position I would probably plug those oil lines, I think there is two but can't remember, and install a manual fuel bulb assembly from someplace like tractor supply. Lastly install a ball valve in the fuel line someplace but it sounds like you already did. I will look through my 70 service manual after a bit but I'll bet those oil lines are your problem.


Would you rather pay a buck for a burger or eat a free sh!t sandwich?


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## OregonJD720 (Jan 18, 2015)

There are two manual valves before the sediment bowl that are both shut. I don't think the gas is going through the bowl into the carb, I think it's coming from the carb vent into the bowl/carb.


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