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running hot

Discussion in '40- & 55-Series Tech' started by 79fj40, Aug 19, 2003.

  1. 79fj40

    79fj40

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    I have a 79fj40 hence the name. My fan went into the radiator a few months back. So I replaced the radiator, water pump, thermostat, and hoses. since then, I run very hot at freeway speeds. When I am driving in the city I run normal. I can't seem to figure out why but I am afraid of blowing my motor. The motor is a stock 2f with 96,000 miles on it. My cruiser is going to be a daily driver until I get back my work truck that got smashed. I bought my 40 about 18 months ago but have not driven it very much, I seem to always have it torn apart for upgrades, so this might be a problem that was already present. Sorry for the long post but I am stuck and tried to give as much info as possable.
    TIA
    Joe, where did my beer go 8)
     
  2. Jonathan_Ferguson

    Jonathan_Ferguson ★ is in the wrong locale SILVER Star

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    Is the Radiator fully topped up?
    Also check that the Expansion bottle is filled to the full line when the Engine is cold.
     
  3. Rice

    Rice SILVER Star

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    I'm thinking of 4 things to check ...

    1. Did the radiator damage from before cause your engine severely overheat when it happened?

    2. Check that themostat was installed properly and has right temp. range.

    3. Re-filling system may have left some air pockets in the engine.

    4. If you have a clutch fan (Is there one for that year?) is it releasing at highway speeds like it should?
     
  4. 79fj40

    79fj40

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    Johnathan, yes to your questions.
    Rice, no the engine didn't over heat, I did it in my driveway. I have changed the thermostat twice, the first one was a stock temp range the second one was a 180 deg one, it is installed correctly.
    Do you know how I can check for air pockets and how to know if my clutch is releasing.
    Thanks for the info.
    Joe
     
  5. bad_religion_au

    bad_religion_au

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  6. 79fj40

    79fj40

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    Thanks bad religion. Why didn't I think of the search :D
     
  7. bad_religion_au

    bad_religion_au

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    because no one does, they just go bugger i got a problem, ask away... i'm guilty as charged
     
  8. s79bj40

    s79bj40

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    and about how many 40s have fan clutches? I could have sworn that they were all direct drive from the factory.

    sam
     
  9. Texican

    Texican s-Moderator

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    All of the 2 F's came with clutch fans, not sure about the last F's or when they stopped the fixed blade. My 73 had a fixed on it.
    Butch
     
  10. CruisinGA

    CruisinGA

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    Pretty sure my F and a half '74 is a fixed metal. I know my buddies '78 is a clutch plastic.
     
  11. sfrolich

    sfrolich

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    Is there a coil spring in the lower radiator hose? If not the engine speed can be sucking the hose shut cutting off coolant flow.

    Scott
     
  12. FJAfrica

    FJAfrica

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    The problem you identify sounds like there is a flow problem in the cooling system.
    Was the new radiator identical to the old one?

    IS the new waterpump the same?

    Was the waterpump installed correctly?
     
  13. 79fj40

    79fj40

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    strolich, I will check to see if there is a coil spring in the hose, thanks for the tip.
    fjafrica, yes the radiator and water pump are the same, and I have removed and reinstalled the water pump twice thinking I might have not installed it right the first time. Thanks for the input
     
  14. Jman

    Jman

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    If ya don't know, I ain't tellin'
    Sorry I'm late to this disc., but I've got exact same problem in 87 FJ60. For me, putting on the heat full blast always does the trick, cooling it down IMMEDIATELY, so maybe my problem is poor radiator flow? Or shot fan clutch? (I'll be pulling over next time it gets hot and trying to turn the fan--AFTER I SHUT OFF THE ENGINE, THAT IS!!!--to see if my fan clutch is shot.)

    It does this on the highway, or on steep, long hill climbs, where it's at high rpm with low air flow.
     
  15. dd113

    dd113

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    Even money it is the fan clutch. Not cheap but replace it. Best deal I have found is @ TPI with fan clutch and WP combo. I think CCOT matches that price also. AFAIK the fan clutch is the same from 76 up to 90ish. NAPA sells them.
    To get the air out of the cooling system: Never had a problem on a 40 series. 60 is a bit of a pain but a 62/80 is a major PITA. It all has to do with the shape/location of the fill neck. Get it to a place where it will be nose up. Turn on FT/RR heaters and top off as needed.
    While you are at it get some good rad flush and clean the block. Might be a small blockage in there.
    You can rebuild the fan clutch. Go to the 3FE list on Yahoo. It has the part numbers in the archives.
    Many variations of fans. There are the 4 blade F fans Direct drive
    6 blade F fan DD, 2 types of plastic DD fans on late F and early 2F 76 or 77 up is the same with a clutch. You can also retro fit a clutch fan to any F series motor and any F series WP will fit except for the wierd long 55 pumps.
    A nice mod for a 40 is a late model WP with oil cooler and a oil cooler from a later model 2F. You would need the 60 or 62 hard lines for the heater hoses. You can drop oil temps a lot. Cooler oil = better motor.