Heater core shutoff valve…revisited

[racerop]

Originally Posted by LuckyLightning

I just drove the truck today for a few hours in the hottest part of the day. I think what I saw was the temp rising before the thermostat opened up. I saw it happen again today - the temp would rise until the thermostat opened up, then go back down to normal. Interesting thing was it happened every time I turned off the truck for more than a few minutes (such as when pumping gas). I assume this is normal operation, but I never noticed it before.

I had a car have the same symptoms as what you are describing. I would flush/refill with new coolant and replace the thermostat. The thermostat is probably sticking while opening.

[tucsonjwt]

After running at operating temperature, then shutting off the vehicle, it will normally increase in engine temperature because the fan is not running and the coolant is not circulating. After sitting for awhile, the engine will normalize to ambient temperature. With a big block this effect is magnified because they have less air space around the engine/exhaust manifold to dissipate the heat.

My experience and $.02,.

[LuckyLightning]

Thanks tucsonjwt, I kinda figured that might be what was going on. Appreciate the confirmation.

[Bigstevex4]

Originally Posted by LuckyLightning

I just drove the truck today for a few hours in the hottest part of the day. I think what I saw was the temp rising before the thermostat opened up. I saw it happen again today - the temp would rise until the thermostat opened up, then go back down to normal. Interesting thing was it happened every time I turned off the truck for more than a few minutes (such as when pumping gas). I assume this is normal operation, but I never noticed it before.

That's normal the heat is rising to the thermostat. I have a Manuel temp gauge at the stat it will rise 20 degrees when shut it off.

[roger97338]

Originally Posted by LuckyLightning

I just drove the truck today for a few hours in the hottest part of the day. I think what I saw was the temp rising before the thermostat opened up. I saw it happen again today - the temp would rise until the thermostat opened up, then go back down to normal. Interesting thing was it happened every time I turned off the truck for more than a few minutes (such as when pumping gas). I assume this is normal operation, but I never noticed it before.

Being able to see the gauge fluctuate like that often means that there are still air bubbles (or one large air pocket?) in the cooling system.

[LuckyLightning]

I believe it roger97338. How do I get rid of the air pocket(s)?

[Liberty]

Originally Posted by LuckyLightning

I believe it roger97338. How do I get rid of the air pocket(s)?

Run it a bit without the rad cap on, should see it burp and drop fluid level. Driving it around can also help. (with the cap on of course!)

[LuckyLightning]

Great, thanks Liberty for the advice.