I just recently replaced my h20 pump, hoses and tstat.
I am finding that as I operate the car, sometimes I will drive is clear cross town 15 mins and 8-10 miles only to check and see that the t-stat hasn't even opened yet.
The temp gauge never goes over 210 or so but when I stop the tstat hasn't opened and I am thinking that it never even opened during my trip because the top rad hose going into the h20 pump isn't very hot by comparison to the lower hose.
a non-contact ir thermometer reveals that the h20 pump was about 170 deg, the stat isn't open yet but as the car sits for about 10 minutes the tstat will eventually open.
The system has been bled multiple times and I 'think' that all air is out.
The tstat is a new acdelco 180, and it will open if boiled.
The weather here in montana is in it's 40's..
how can the engine cool if the tstat doesn't open?

anyone have any idea about what's going on here?
Thanks,
Tal

 

Put it on the stove in a pot of water. Turn heat on and boil water. Time it with a watch.
It won't open if the engine isn't producing enough heat to open it.

 

180* is the temperature it STARTS to open. It may not fully open until it hits 200*.

 

If you're driving in 40 degree weather, you probably have the heater on.

The heater can provide quite a bit of engine cooling by itself, particularly in cold weather.

 

Thanks guy's!
I was wondering if it was all weather related as it hasn't been more than 45 degrees in weeks.
I was most concerned about the apparent lack of heat in the top radiator hose.
The heater goes like gangbusters and I guess it could be removing enough heat to stop the tstat from opening.
The engine is nowhere near overheating, typically it doesn't go higher than the midpoint.
Am I worring about nothing at all?
The new stat has already been boiled to confirm that it does in fact open.

Thanks for your replies
Tal