Thermostat Problem
 

I have 2005 blazer,4.3 litre with 90,000 klm.I noticed last summer that the temp gauge was a little hotter than average,not over heating but I know where my gauge usually sits,now in the winter the gauge is not moving much and I am not getting the heat I used to get,does this sound like a simple thermostat failure.Antifreeze is clean and topped up.All fans and vents are functioning normally,just not getting the heat im used to.Any help would be greatly appreciated.

Blazer Guy

If the gauge is running low and your heat went cool as well sounds like you nailed it, the thermostat is stuck open. Could be (probably) in the summer it was stuck in that spot as well, not quite open enough.

Thanks your responce RonJon,for all a thermostat cost,I will replace that next week and see what happens.

Blazer Guy

yep, mine ran cooler before i replaced mine.

Thanks blazinloud,I figure the thermostat is the perfect place to start trouble shooting............the symptoms have thermostat written all over it.

Blazer Guy

ever since i bought my 97 blazer the coolant temp never exceeded 155 degrees according to the gauge, and since we have had -1 to -15 degrees the last week i looked into it, the heater did not work very well at all, i changed the thermostat, and now it will get up to around 190 till the thermostat opens, then the gauge heads back down to the usual 155, again, it will climb till the thermostat opens and then go back down, any ideas on this situation, almost as if gm over designed the cooling system!

On the 4.3 replacing the thermostat sometimes addresses the symptom, not the problem of low temp and low heat. Low temp and low heat are often caused by air getting into the cooling system. The two main culprits are a intake gasket leak or a water pump in the beginning stages of failure.

Replacing the thermostat temporarily masks the above problems as air is often replaced with new coolant after the thermostat change, but in time the coolant weeps out slowly and the poor heat temperature returns.

A radiator pressure test is required to truly identify the cause of most 4.3 cooling/ heating issues.

Finally got of my arse and the weather was cooperating today,so i changed the thermostat in my truck,temp gauge goes up more and the truck now has lots of heat,I took it for a run on the highway and things seem to be back to normal.Thanks for all the help guys.