Hello everyone,

I have solved a lot of problems with my Blazer using the helpful people on this forum. One of the “simplest” problems it would seem, that I cannot solve is this:

I’m in Alberta, Canada (I'm posting to the USA due to significant likelihood there are a lot more people who have experienced and solved this problem) My 1997 Blazer warms up to the 1/4 mark on my temperature gauge (155-160F / 70C) no matter how long I’m driving it will remain there. When I’m stopped at a light it seems it creeps up a tiny bit, but sounds and feels like the engine is under load when I get going making me believe the the fan is trying desperately to get it back down to the 1/4 mark on the temperature gauge. The heat is fine when it is about (15F / -10C) outside, however anything below that the cabin struggles to stay warm.

I have replaced the thermostat twice, have changed the CTS. My blazer has one that the ECU reads that is pretty much right in front of the thermostat and one that gives me the gauge reading (1 pin) further down beside where one the spark plugs lives on the driver side. Given the symptoms I’m experiencing, I don’t believe it’s a false reading or that the temp sender is faulty. I believe the fan is engaging prematurely for whatever reason, however someone who is more mechanically experienced could have a different explanation and I could be wrong. The thermostat is the only thing I could think of that makes sense but unless I’m just unlucky and have gone through 3 thermostats since buying this Blazer all being faulty I don’t think that’s it. I have bled the system of any air as well, and the 50/50 Dex-Cool is all topped off.

If someone can please help me out, or tell me how they solved this problem if they have experienced it. That would be very helpful. Otherwise I might go clinically insane.

Thank you in advance!

(P.S. if anyone has the solution, and it works out. I will send you money to buy a case of beer)

 

Apparent overcooling. Right?

Are you confident of the actual temperature? Have you done a separate measurement of the temperature of the thermostat housing with a thermocouple or IR thermometer?

 

Hello!

thank you for replying! So I just took the temp. The T-stat housing is about 200F at the flange and above, and just below it drops in temperature to about 165F

upper Rad hose is 150F

lower rad hose is 120F

 

Agree with Christine with comparing the gage reading with a IR gun. If it does match, pull your thermostat out and boil up some water with a thermometer in the water. That will tell you what temp it is opening up. If memory serves, it should open at 195 F.

 

Hello!

thank you for replying! So I just took the temp. The T-stat housing is about 200F at the flange and above, and just below it drops in temperature to about 165F

upper Rad hose is 150F

lower rad hose is 120F

 

Yes 195, I will do this ASAP! Thank you

 

Yes! Do the hot water test for the thermostat on your stove.

I'll be interested in seeing what you get since your separately measured temperature at the t-stat housing is about what one would expect for an engine at full operating temperature.

If it turns out that your thermostat is fine, could it be that the thermostat on the fan clutch is not working? I.e., Is the fan clutch not disengaging the fan as it should when the air temperature aft of the radiator is low?

 

would love to know what the end result was!
same problem with my 2001