Hello,
I have a 1996 chevy s10 4.3 X vin. I've been driving this truck for a while and the temp gauge has always read about 150 degrees when hot and running. I've been reading on a few forums and talking to people and they say that running that cold could damage my motor and that 195 degrees would yield more mpg's and would increase the overall health of the running motor. I recently changed my thermostat to a 195 degree thermostat and theres a problem. when I cold start and drive the truck it gets up to 195 degrees but when the thermostat opens the temperature shoots back down to around that 150 range and stays there. The thermostat regulates it to that temperature instead of regulating and holding it steady at 195. when it starts climbing again itll get up to no higher than 160-65 and then go back down. can anyone give me an idea of a diagnosis?

THANKS

JB

 

I've had this exact same problem. Exactly as you describe it. Spent hours bleeding the cooling system of any air pockets-no success in wasting gas in the drive way... Changed the thermostat twice now thinking maybe I am just unlucky and got a DOA stat... nope.. no change. Truck still drives, but it is quite frustrating. I just want the dang gauge to stay dead center where it should be.

 

Could be a bad engine coolant temperature (ECT) sensor.

 

Getting the air out of the system is a battle sometimes.

But you should definitely check the ECT sensor.

 

The coolant temp sender below the thermostat is for the engine module,the sender on the left head is for the guage.Just had to change mine as age/corrosion was giving false readings for the guage.

 

I'm glad im not the only one! it drives perfect, just want it to run at the proper temperature, or read the right temperature. the first thing i thought was the sending unit, but i would think that if it would be the sending unit, then the gauge would be all over the place. it looks like it is reading pretty accurately, just too cold.

 

I replaced the sending unit when I replaced the thermostat the 2nd time around. Made sure it was all teflon'd up. I did purge air from the system as per instructions in another post. Gauge still will not read a steady 210 tempurature. Moves all the way to 210 at warmup, then spends the rest of its time fluctuating around the first quarter mark... I know how frustrating this can be. The cooling system on the 4.3 isnt exactly the easier to work with either.

 

well thats exactly the line mine reads aroudn as well. oh well. ill figure it out. i have a few of the best mechanics and car guys in town in my contact circle because of my dad's 45 year history as a body man. we'll see.

 

Let me know when they find whats wrong with yours so i can try and fix mine. I don't exactly have all the good connections.

 

Ill get to it as soon as college permits. schools getting pretty heavy next week because of tests and the like.