The temp guage on my cossie is reading way too hot, it makes me shit myself everytime I drive more than 10 minutes away as the needle will be touching the red, but the engine, radiator and coolant pipes are all still just luke warm. It had all new temp senders when it had the head rebuilt last month and everything was working fine until then.

Any ideas?

 

did it have a new gauge sender, the single post that looks like a short piece of threaded rod that connects near teh ECT sensor for teh ecu.

if you pull the plug off the end, and short ot to the engine with the ignition on, it should go all the way to the top, this will prove the operation of the actual gauge.

 

It had a new ECT sensor and also the temp sender you're talking about.

 

so with the gauge sender disconnected, the temp gauge should be off teh bottom of the scale, with it shoprted to the engine/chassis, it should send the gauge right to the top, this will eliminate the actual gauge,

could be the wrong gauge sender....?

 

That'll definitely do it...

I remember years ago when i had an assortment of senders, all looked exactly the same, but the internal resistance that controls the output to the gauge varied so much, i could go from nothing on the gauge, to normal, to off the top by testing it with the different sensors.

I suspect if you are absolutely certain it is running at the right temp, then you could use a small trimmer pot wired in series, and trim it down to the normal region instead of buying a new sender...

 

Guage is definately working properly so it makes sense that it'd be the incorrect sender as thinking back to it, the parts supplier I got it from said that all Sierra temp senders are the same so just grabbed one off the shelf. Didn't give it a thought that it would be different as it looked and fitted exactly the same.