General coolant question

[fordysenior]

With these newer vehicles having overflow bottles, how do you know your thermostat is opening properly? In the old days, we just looked into the radiator. But if the thermostat is open, will I see any movement in the overflow bottle?

 

[2001AWD5.0]

no
because it is part of the coolant reserve (cold) and expansion (hot)
most the systems now have bleeders to vent air from the system as you fill system
i do all of my own work on my cars since 1973, starting with 1969 ford torino ( back then they just overflow bottles and to vent air out of the system)
hope that helps

 

[fordysenior]

I expected the answer to be no, but figured I'd ask. I have my Explorer and I have a '99 F150 -- both with the 4.6 engine. In the truck, I recently replaced the heater core and can't get the air out of the system. I hear it moving around when I step on the gas. I was thinking maybe I'm not getting proper coolant movement through the system.

 

[Number4]

Idle the vehicle the AC on. When the needle reaches the middle of the gauge, it's at least 194 degrees. If the t stat doesn't open, then the gauge will continue to rise. Though the needle will stay in the center until 230 degrees or so, when it will jump up.

 

[field]

Is there a reference or a reason for that jump to 230F?

 

[lincolnshibuya]

if the thermostat is open, the temp gauge will never reach almost halfway especially if you are driving in the freeway.

 

[field]

Cools apparently fine with out pressure.

My temp gauge has always gone to the same middle of it's range after a few minutes of driving. Really always. But there is never any pressure release when I remove the radiator cap even immediately after driving. Really never. This concerns me.

 

[fordysenior]

How old is the radiator cap? Maybe it's bad and won't hold pressure

 

[field]

I recently got a new radiator cap. Logically, I'll do a coolant pressure test next and hopefully that will disclose any present leaks and not blow out a new leak.