no heat - solved

Had a coolant leak so replaced water pump and thermostat while I was at it. Still had a leak and found the problem was the radiator, so I replaced the radiator. No more leak, but no more heat either. Could only get heat into the truck if I let it idle for a long time. Driving would eliminate the heat and it would blow cold. I determined it was a thermostat problem, so I dug through my garbage for the box it came in. It was the right temp, but a "fail safe" t stat. So, wfter replacing the pump and t stat, with the bad radiator, it still overheated and that tripped the fail safe t stat into locked open position, thus, no heat. I just need to replace the t stat and all will be fine. I didn't know I had bought a fail safe, didnt even know what it was till I saw the box. Thought I would share this.

Dave

I thought that fail safe meant that if it went bad, it would break in the open position. It does not mean that if it overheats once, it locks into open. It should still close when cooled down. That said, I have heard about tstats being ruined by being overheated. Normally, however, that is not the case.

sounds to me like the blend door is flapping

winterbeater said:

I thought that fail safe meant that if it went bad, it would break in the open position. It does not mean that if it overheats once, it locks into open. It should still close when cooled down. That said, I have heard about tstats being ruined by being overheated. Normally, however, that is not the case.

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The truck over heated after the install of the new T stat cuz the radiator was still bad. I should have replaced the T stat after the that over heating incident. The box says that it breaks in the open position, so you can limp home to repair it without over heating. It is also self-described as one -use only. It also says once it does that, it needs to be replaced cuz it won't close. I am not going to get another one. I'll use the standard kind. Wish I realized which one I bought at the time. you live and learn.

ehall said:

sounds to me like the blend door is flapping

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I checked that out, too. All is fine. Other tell tale symptom is slow to warm up, and never gets close to running temperature. My guess is 140 or so degrees, unless I let it idle without pulling air thru the radiator, then gets warmer and can get some heat.

Stant makes a deluxe model. It's only like $6 or $8. It looks like the best bet to me.

winterbeater said:

Stant makes a deluxe model. It's only like $6 or $8. It looks like the best bet to me.

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Agreed.

Dave Meyers said:

I checked that out, too. All is fine. Other tell tale symptom is slow to warm up, and never gets close to running temperature. My guess is 140 or so degrees, unless I let it idle without pulling air thru the radiator, then gets warmer and can get some heat.

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yeap tstat is stuck

Yup, removed the single-use fail safe tstat, it was locked open I installed a stock replacement. Heat works well, no coolant or tranny fluid leaks. Just in time, it is getting cold in Wiscsonsin, need heat in the truck, and don't want to wrench on it in the cold.