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720 gas in the oil

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Victor

06-25-2001 12:28:25




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I have a JD 720 which doesn't seem to run right. I had the carburetor rebuilt, but it still sounds like it works too hard. I also go through 4-5 gal per hour.. The gas leaks into the oil. Help.

Vic




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john

06-25-2001 17:03:39




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 Re: 720 gas in the oil in reply to Victor , 06-25-2001 12:28:25  
I would bet the float in your carb either has a hole in it (if its the metal one) , or if its the foam looking one has become fuel logged (absorbed fuel and become heavy so that its not shutting off the fuel like its supposed to). At any rate the easy way to check would be to get her under a load and turn the fuel off (be careful not to fall off while doing this).if this is the problem you will probably have a few seconds of good running before it dies, due to the fuel not pouring into the cylinder at the wrong mixture. At any rate if the kit you bought didnt have a new needle and seat and a new float, I would replace them you can buy these pcs. seperatly and are fairly cheap. good luck.

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Gator

06-25-2001 19:28:37




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 Re: Re: 720 gas in the oil in reply to john, 06-25-2001 17:03:39  
To solve the gas/oil problem, replace the diaphrams in the top of the settling bowl. The oil pressure line passes thru to the gauge and if the diaphrams are leaking gas will flow to the crankcase. I had this problem on my 630. Good luck.



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MIKE HANLEY

06-26-2001 21:14:16




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 Re: Re: Re: 720 gas in the oil in reply to Gator, 06-25-2001 19:28:37  
THE HOLE IN THE RUBBERS IN THE TOP OF THE GLASS BOWL IS THE MOST COMMON GAS IN OIL. LESS THAN $10.00 TO FIX. BUT YOUB HAVE TO DRAIN THE TANK...OR GET A WET STINKY ARM AS THE WHOLE ASSEMBLY HAS TO BE UNSCREWED FROM THE TANK. REMOVE THE SCREWS FROM THE COVER AND YOUR THERE.

WATCH WHEN REMOVING THE LITTLE C CLIP SPRING AS THEY WILL GO FLYING.

ALWAYS RUN THE TRACTOR WITH THE NUT ON THE TOP OF THE ASSEMBLY TIGHT AS IF LEFT LOOSE IT WILL WEAR THE RUBBERS. IT IS ONLY USED TO FILL THE BOWL OR WHEN YOU ARE FLUSHING THE CARB.

JUST BECAUSE THE CARB WAS OVERHAULED DOSN'T MEAN IT WAS AJUSTED. 520 TO 730 ALL AJUST THE SAME. THE OPERATORS MANUEL COVERS THIS IN DETAIL.

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MIKE HANLEY

06-26-2001 21:23:13




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 Re: Re: Re: Re: 720 gas in the oil in reply to MIKE HANLEY, 06-26-2001 21:14:16  
ADDITIONAL...ALSO REPLACE THE LITTLE "o" RING AT THE BOTTOM OF THE SHUTOFF. YOU CAN SEE THAT WHEN REMOVING THE GLASS BOWL AND THE SCREEN.

THIS SHOULD BE ALL TAKEN APART ONCE A YEAR AND ALL CLEANED AND INSPECTED.



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BOZO

06-25-2001 20:27:00




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 Re: Re: Re: 720 gas in the oil in reply to Gator, 06-25-2001 19:28:37  
Shouldn't the oil pressure keep the gas out while running? When I first brought my 820 home (I live in town) I killed all the mosquitos in 2.5 acres by letting the starting engine continue to run. After replacing the two diaphrams in the fuel cutoff, the blue haze dropped to a respectable level.



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Gator

06-26-2001 09:28:28




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 Re: Re: Re: Re: 720 gas in the oil in reply to BOZO, 06-25-2001 20:27:00  
Thanks for the reply. John Deere Contrived this setup so when there IS oil pressure it holds the valve open to let gas go from the tank to the carb. When the pressure drops it shuts off the fuel supply and when the carb is empty it kills the engine. I have started several tractors by lifting the knob on the top of the carb after it had dropped and stuck shutting off the fuel supply. With an 820 the fuel is pumped to the cylinders and the starting motor runs off gasoline from a different tank. Also the starting motors on some of the big diesels were two stroke and did smoke a lot. We sure could use that "fogger" here in southern Wisconsin as the skeeters have just woke up hungry. Gotta Putt, John.

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