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  1. #1
    New Member
    Join Date
    Jan 2008
    Posts
    5

    Default 790 Operating Temperature

    The instrument panel on my 790 works intermittently. I want to install a mechanical temp gauge. Does anyone know the maximum operating of the engine?

  2. #2
    Silver Member Whitey's Avatar
    Join Date
    Dec 2007
    Posts
    249
    Location
    Slippery Rock, Pennsylvania
    Tractor
    Kabota B21 TLB

    Default Re: 790 Operating Temperature

    Have you tried the JD web page?
    John Deere 425 AWS / 54" MMM / 54" Sno Blade / Kubota B21 TLB

    A patient man has great understanding; but a quick tempered man displays folly.

  3. #3
    Elite Member
    Join Date
    Jul 2006
    Posts
    4,409
    Location
    Northwest, WA

    Default Re: 790 Operating Temperature

    My tech manual says "69.5 - 72.5ー C (157 - 163ー F)"
    ::Sent from a standard desktop keyboard::

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  4. #4
    New Member
    Join Date
    Jan 2008
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    5

    Default Re: 790 Operating Temperature

    Thanks for the reply.

  5. #5
    Elite Member RalphVa's Avatar
    Join Date
    Dec 2003
    Posts
    3,758
    Location
    Charlottesville, VA, USA
    Tractor
    JD 1025, previously Gravely 5650 & JD 4010

    Default Re: 790 Operating Temperature

    Reware of installing gauges that show exact temperature. The hotter thermostats are set at about 195 F, but you'll likely never see this on a temperature gauge. Never change out a thermostat based on what you see on a gauge. Did it once and saw no change and buggered up the aluminum threads in putting the "stat" back in. Best to leave the beast lie if its working at all. Thermostats either work or they don't, unless something gets caught underneath them that keeps them open. If it works to open and close, doubt it would fail to open at the right temperature. It's a pretty simple device. What's more likely to go bad is the sensor. Had that happen on a 1973 Benz, to the sensor that turned on the auxilliary fan.

    My old (1983) Benz runs at 85 C most of the time but runs up to 95-100 C in the summer while running fast in summer heat. Has never overheated to point of boilover. Part of this heat increase is probably due to the timing chaing stretching and decreasing the valve timing about 6 degrees (in 210k miles). I may replace the timing chain this next summer and see what it does to the running temperature and fuel mileage. With antifreeze at about 50/50 mix, think the boiling point is 220 F.

    The VW and Tacoma just run at mid point on the gauge. Have no idea what the actual temp is.

    Ralph
    The natural gardener
    God's original intent

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