Ford Ranger Cooling

A 1995 Ford Ranger with a 4 Liter engine and 170K miles has a temperature problem. The temperature gauge cycles to high and back down within 10 to 15 seconds at highway speeds. It happens more often while climbing a grade. Down shifting will bring the temp gauge quickly down within a few seconds. The radiator, water pump and thermostat were replaced at about 150K miles. Coolant level is OK.

Can lower octane fuel be a factor?

temp cycles up and down to what? over heating, or just fluctuating?

it may be something as simple as a temp sender unit. but you should figure out if it is indeed overheating. you have not been clear on that.

You might have air in the system. Try running your engine for a little bit with the radiator cap off (engine cold, of course). Also try changing your radiator cap if that hasn’t been done lately.

Agreed. I have used the absence of temperature cycling to detemine when all the air was out of a system after a coolant flush. If this started recently there may be a head gasket leak or maybe the antifreeze water mixture is wrong and this is simple boiling.

I will check on if it is actually overheating.

The gage normally read about 10 to 20% to overheat when running OK. The fast cycle up goes anywhere from 60% to 90% to the top of the gage.