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Subject: 641 - gas in oil (again)

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Mike in Michigan    Posted 07-25-2018 at 18:14:50 [URL] [DELETE]        [Reply] [Email]  
  • 641 - gas in oil (again)
  • I rebuilt the carb a few times and again have gas in the crankcase. I turn the gas off after each use by turning the screw directly beneath the tank.

    The 75 Tips paper says "The fuel shut-off valve on the sediment bowl is there for a reason...".

    Is there a difference where the fuel needs to be turned off?

    Mike in Michigan    Posted 07-29-2018 at 21:32:49 [URL] [DELETE]        [Reply] [Email]  
  • Re: 641 - gas in oil (again)
  • Thanks for all the tips guys. It took a while for the gas to appear in the oil, but I have been living in the city with the tractor in the garage only starting once a month or two.
    Hopefully I will be able to find a quality replacement shut off valve. Let me know if there is anything unusual with replacing the shut off. Could the consistent problems with the carb/float/gas-in-oil also be caused by dirt in the gas tank?
    Is there anyway to clean the tank in-place? I'd rather not remove the tank if possible and do it in conjunction with the shut off valve.

    HCooke    Posted 07-27-2018 at 07:24:52 [URL] [DELETE]        [Reply] [Email]  
  • Re: 641 - gas in oil (again)
  • The fuel shut off valve in the 01 series is subject to failure. It needs to be replaced.

    Gaspump    Posted 07-26-2018 at 14:49:38 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 641 - gas in oil (again)
  • Two probs. One gas is leaking or sleeping past the float valve. The other is the same problem with the fuel shut off under the tank. Even though the float valve may seat well 99% of the time it can get an obstruction and leak, that is why you turn the tanh valve off. I never fail to turn the shut offs off on my N's or my 960. Now about 5 Years ago I found gas in the oil of my 960. The valve had been turned off so I removed and disassembled it expecting to find a bad O ring. I was surprised to find the O ring in good shape but the ball shaped seating part of the valve was badly eroded by the ethanol in the gas. The original valve lasted over 50 years but ethanol did it in.

    BlasterStumps    Posted 07-25-2018 at 21:17:46 [URL] [DELETE]        [Reply] [Email]  
  • Re: 641 - gas in oil (again)
  • I suppose I deserve to be roasted for suggesting this but, might look at putting an inline shut off in the gas line. I have one in the line on my NAA. I put a new fuel shut off valve and sediment bowl in the tank but it leaks. New stuff is mostly crap if it comes from some place else. The inline valve is just a brass valve 1/4" or so. When I shut the tractor down, I turn the fuel shutoff valve off and then go around on the other side and turn the 1/4 brass valve off. I wait until the engine starts to sputter a little then I turn the key off. I might still get a drip at the fuel shutoff valve but at least the carb doesn't fill up and cause the gas in oil problem.
    Ok guys, let me have it. : )

    Tony C    Posted 07-26-2018 at 18:58:04 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 641 - gas in oil (again)
  • Nope, a simple elegant solution solution for a seemingly complex problem in fluid dynamics.

    Positive shut off valve at the carb, below the sediment bowl or above the bowl. Take your pick. Whichever is easiest to access.

    Mike hasn't said how long it takes to get oil dilution or how bad is it. If it develops over an extended period a incorrect main jet adjustment, over choking a hard starting engine (more common in winter) can cause oil dilution.

    Bruce (VA)    Posted 07-25-2018 at 19:33:06 [URL] [DELETE]        [Reply] [Email]  
  • Re: 641 - gas in oil (again)

  • no.

    Your float is sticking and the cutoff valve is defective.

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