temp gauge fluctuating

[Brian Johnson]

I have a 94 ranger 4.0 with a fluctuating coolant gauge. the thermostat was just replaced along with a head gasket repair. The needle will rise from the N on normal to just above the L then drop back to the N. this happens continuously in 5 to 10 second incrinents. once the engine is warm.

 

[pwrranger88]

it sounds like the temp sensor is going bad i had the same problem until i replaced it

 

[footee]

You may have the wrong temperature thermostat. All my Rangers and Explorers do that, albeit not that hot. Basically, when your temp reaches that certain degree, usually around m on mine, the thermostat opens up and it cools back down to around the n. Then it closes again, which is where the fluctuation is.

 

[Brian Johnson]

Thanks, I will ck the sensor and thermostat. I Put in a Stant thermostat when I replaced the Head gaskets. Maybe I should go to the motorcraft stat?

 

[adsm08]

Meh. I usually try to push the motorcraft parts, but as long as its set up for the right temp range a thermostat is a thermostat.

 

[177CIOfPureLove]

Check your grounds. Mine did that for the longest time.

 

[locovaca]

+1 on the wrong temp thermostat. My sister had a Taurus and her fiancee stuck in one that opened at too high of a temperature. Everytime it would get hot the cold coolant would flow in and close the stat, lather rinse and repeat. It took 15-20 minutes of straight driving to get the entire cooling system at a temp where it would keep the stat open.

 

[modelageek]

I always push the correct temp motorcraft tstat also. it could be the sensor/sender. I don't know about the 4.0 but my 2.5 because of where the sensors/senders are located unless my coolant level is total full. the temp gauge will fluctuate with increased rpms because coolant is flushed over them.