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Ford Ranger Radiator Issues



  • bolivarbolivar Posts: 2,316
    1) Blowing coolant into overflow tank. I assume it's overheating, right? If so, you need to fix overheating problem - stuck thermostat, clogged (inside or outside) radiator, head gasket leak, etc.

    2) To get coolant back into the radiator from the overflow tank, the rubber line from the top of the radiator to the overflow has to be air tight. No cracks, etc. If it is not airtight, air is pulled back into the radiator, not coolant from the tank. Also, the radiator cap has to be working correctly. It basically has a two-way valve in the top of it. If the radiator overheats, the pressure goes up and at a certain pressure the valve opens and coolant flow thru the rad cap, thru the rubber tube, into the overflow. When the rad cools down, the creates a partial vacumn in the rad which opens the valve in the cap in the opposite direction, allowing coolant to be 'sucked' back into the radiator from the overflow tank.

    So, you can see that the radiator cap, it's valve, must be working correctly and there can be no air leaks in the rad cap seal to the radiator and in the rubber hose to the overflow tank. And, in the overflow tank, there is a tube that goes almost to the bottom of the tank. It must be in place, and the hose connection to the top of this tube must not leak, so the coolant will be pulled back into the radiator.

    Oh, and all the other rubber lines in the cooling system must be air tight. If you have a small leak in any of them, rad hoses, heater hoses, etc, then when a motor cools down, air will be pulled into the system at the leak, and it will not form the vacumn to pull coolant back from the overflow tank.

    As a matter of fact, you might have a head gasket leak. This causes a motor to overheat significantly, which would blow coolant into overflow. But with a bad gasket leak, air could be pulled back thru the gasket and coolant not be pulled out of the overflow.

    Basically, if the truck is overheating, you need to work on that first. If it's a head gasket, this is big money to fix.
  • tiny43tiny43 Posts: 1
    I have a 96 2.3 4 cyl and i cannot find the sending unit my temp gauge pegs out hot always but the truck never runs hot so I am assuming sending unit gauge or connection is bad but I cannot find the sending unit. All suggestions and info will be appreciated.
  • check at or very near the thermostat. it is not part of multiwire harness. should be a single wire lead to the sending unit. once you "think" you have it located, disconnect it and see if the temp gauge goes to zero.
  • We are having the same problem described with the overflow tank blowing open and spraying coolant all over, We tried replacing the temp sending unit and sensor but still having the same problem. We are going to try replacing the waterpump next, Has anyone found a solution to this problem?
  • i have an 98 ranger with a 4.0 when i turn on the heater my temp gauge will go up and down.i have redone the heads and clean the radiater to and a new heater valve is leaking a little and i belive its pulling in air with the heater on.the truck never gets hot.with the heater off its fine.
  • bolivarbolivar Posts: 2,316
    Replace the valve, it's a known problem, with the symptoms you've described.
  • im going to next payday.this has been a good has 115000 miles on had 32000 on it when i got it 3 years ago. :shades:
  • did replacing the water pump work cause thats the only thing i havent done
  • my truck has a plastic heater valve ,it was leaking a little around the shaft with tthe heater was sucking air and making air pockets and when the air would hit the sencer for the gauge it would go down and when it passed and the nwater came back the gauge would go up.i replaced the heater valve and since i did that it has been ok.
  • I have a 1998 3.0l Ranger and cannot figure the coolant problem out. The heating system worked fine until I flushed it last year. SInce then, I have replaced the thermostat twice, the second time with a quality replacement part, bled the air out of the system, replaced the rad cap, and that hasn't worked.
    The symptoms are: coolant goes to reservoir but will not return. When I tried to get the air out, I followed protocol, but upon opening the throttle to 2000 rpm and completing the fill, the rad fluid just gushes out the open rad neck. I get heat upon initially running the engine, but once the fluid is kicked into the reservoir, heat ceases. The temperature gauge never goes above 1/2 way, and it is not over heating. I do smell coolant in the cab, but not sure if it's just from the top popping off the reservoir. The exhaust has been noticeably thicker and whiter, and no coolant leaks can be detected other than the reservoir overflow.
    Both upper and lower hoses are warm when running, and the water pump does make a ticking noise when running. Please tell me it is either a water pump or even a heater core, not a head gasket. I'm not sure........

  • bolivarbolivar Posts: 2,316
    Bad radiator cap? It get hot and pushes coolant to the overflow reservoir, but the little valve in the cap is not working right. It's not opening up when it cools down and pulling the coolant back into the radiator.

    Or, the rubber hose from the cap to the reservoir is bad. Somewhat same problem, it pushes coolant to the reservoir when hot, but when cooled down the hose allows air to be pulled in rather than coolant from the resevoir.

    Or, it there is a leak in any of the hoses - radiator or heater - the same thing happens. When the coolant cools down, air is pulled into the system rather than coolant being pulled back from the reservior.

    In general, the cooling system has to be air tight everywhere or there will be problems.
  • i have a 1998 ranger xlt and the temp guage goes crazy when you start the truck it goes from cold to hot but does not overheat. Also when going from park to drive it dies but does not when shifting any other time. thanks
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