I have a 1994 4.0L Ford Ranger that will overheat. The temperature gauge will "bounce!!"

Question

The temperature will goes to the high normal range for a few second and then it will goes back to the midrange or sometimes just below the midrange?..we've changed the thermostat and there is no white smoke coming from the exhaust. Could this be the radiator? Maybe needs to be flushed out or replaced?

Answer 1

Sounds more like a faulty temperature sending unit.

Answer 2

Don't worry. I have an eighty one ranger which is such a piece of c**p. Just feel lucky. No air condit. or heater and it sounds like a sherman tank which i'm pretty sure isn't legal!

Answer 3

SOUNDS LIKE AIR IN THE COOLING SYSTEM ,THE ITS A FAN CLUTCH

Answer 4

You are saying it goes to high normal? Does not go to red? You are not experiencing any over heating problems? If this is what you are seeing then you have a very delicate ( sensitive ) gauge -r- sending unit with nothing to worry with. If this just started then  I will suggest not to overlook the water pump not the cooling fan. Checking the centrifugal cooling fan when the vehicle reaches normal operating temperature then make sure air is flowing from the front of the radiator using a piece of paper to see if it will hold it against the front of the  condenser when you put it against it and release it to see if it stays there by itself.. Water pump then if your coolant reservoir is visible then when reaching normal operating temperature you should see the movement of the coolant when the thermostat opens and allows the coolant to circulate if the water pump is operating properly.

Hope this helps and have a great weekend.

Answer 5

Replace the temperature sensor, this is something that should be cheap and easy to do.  If the problem persists then it is almost certainly a head gasket, cracked head, or cracked block.  The last two are unlikely but possible.  You'll need to have the cylinders pressure tested, a fairly inexpensive job.  If the radiator was bad, even if there was something loose inside which was intermittently blocking the coolant, the effect would be longer lasting.  Your problem is closer to the sensor.  If the head is cracked you will have to make a decision to either fix it, sell or trade it, or drive it until it dies.  I have used K&W block sealer with some success on vehicles not worth the cost of engine repair.  It's temporary at best.