John Deere 425 oil rising

DSteve34

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I have a JD 425 in which the oil seems to rise over time. The coolant levels seem to stay the same so I figured no coolant was getting into the engine. I do wonder if gas is getting through the carb and into the crankcase while it is sitting. Is there any common problems with these engines that causes this? The engine is a kawasaki liquid cooled 20 hp horizontal shaft. Any info appreciated.
 

zman111666

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Fuel getting past the carb, especially when not running is more of an issue with mowers with top mounted, gravity fed tanks. Those water cooled JDs have the tank under the seat, no? I would be suspicious of the mechanical fuel pump in the front of the motor. They have a weep hole that is supposed to let fuel drip out to the ground if the pump goes, not sure if they might drain into the block instead on occasion.
 

DSteve34

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That's what I was thinking to as far as the gas tank not being gravity fed but someone told me it might be siphoning into the carb. As far as the fuel pump I did work on a kohler with a mechanical fuel pump that leaked gas through the pump. Maybe I'll check it out. Is there any way to test the pump?
 

ILENGINE

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Does the oil smell like gas, to confirm that is what is actually causing the level to rise. With the top mounted carb above the fuel tank I would suspect fuel pump leaking into crankcase. If the carb was leaking I think it would run rich or try to flood out.
 

zman111666

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I'm not sure exactly how to test that pump, except by maybe pulling it off, plugging off the outlet, leaving it hooked to the gas, and manually operating it and seeing it gas is squirting out somewhere it shouldn't, but that seems like a pain...

Is the pump clean on the outside? Is the weep hole clear? Does it show signs that it may have been leaking at least some? The aftermarket pumps are harder to tell, as they have a drain hose down to the mower frame. The older ones just had a tiny hole on the front of the pump.
 

DSteve34

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I just found out today that it actually has an electronic fuel pump located back with the gas tank so it can't be the fuel pump. I have experience with gas in the oil on other engines and usually the dipstick shows extremely over and you can smell the gas. Mine is rising very slowly and I can't smell gas. Also doesnt look milky like water being in the gas. My thinking is that if it is rising because of gas it is a very slow leak and wouldn't cause it to run rich.
 

zman111666

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Yeah, looking at it now, i got nuthin'... I was thinking of a vertical shaft engine, with the radiator laying flat on top the engine, but you have the horizontal. Maybe drain all the oil , if it hasn't already been changed already recently. That way you can really take a good look, smell it, put a little on your salad... ok, maybe not. But your setup certainly doesn't lend itself to sneak gas past while it's not running. And you are right about water usually being pretty evident when present. Only other thing I can think of is oil fairies tiptoeing around at night...
 
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