Overheating at Idle
10-01-11, 02:59 PM
#31
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No, it would have been stuck somewhat, not completely, closed and not allowing the coolant to flow freely. When ya drive, the RPMs go up and the waterpump is spinning harder which in turn would push the coolant harder through the system, which is why it would cool down. (And more air would be hitting the radiator) At idle, there probably wasn't enough pressure for the coolant to flow through a half stuck T-stat. If it was stuck open then the coolant would flow through freely and not overheat and also not get hot enough to give any heat.
Glad ya got it staying cool but, I had a "fail-safe" in mine which only lasted a couple months before I had to change it out again. Hope yours lasts longer.
Glad ya got it staying cool but, I had a "fail-safe" in mine which only lasted a couple months before I had to change it out again. Hope yours lasts longer.
Glad you got her fixed!! Ride on.
10-01-11, 05:18 PM
#32
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Yeah this makes more sense. I had a failsafe one that I had to change out in a couple of months because I had a bad fan clutch and it would still overheat. After I fixed the fan clutch issue the failsafe Tstat was stuck open and I was back in there putting in a regular one.
Glad you got her fixed!! Ride on.
Glad you got her fixed!! Ride on.
Makes sense that you would have some issues with the T-stat if your fan clutch was faulty. Sounds like the fail safe did what it was supposed to do.
10-02-11, 06:14 AM
#33
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The thing that happened with the bad one was it was stuck completely closed. The coolant wasn't flowing at all and the temp gauge would go all the way up. But it wasn't overheating, maybe b/c I would only drive it a few miles at a time. And it turns out, the T-stat I put in to replace it was
....a "Fail-Safe". 
Why would I do that, maybe b/c it was cheap? Eh, it's over a year and still good so I'm mixed on reliability, one good and one bad.
10-02-11, 08:27 AM
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I just looked into the past. (threads and reciepts) I was wrong, my "Fail-Safe" T-stat lasted about 9 months, not just a couple like I thought. Still, it died way before it should have.
The thing that happened with the bad one was it was stuck completely closed. The coolant wasn't flowing at all and the temp gauge would go all the way up. But it wasn't overheating, maybe b/c I would only drive it a few miles at a time. And it turns out, the T-stat I put in to replace it was....a "Fail-Safe". Why would I do that, maybe b/c it was cheap? Eh, it's over a year and still good so I'm mixed on reliability, one good and one bad.
The thing that happened with the bad one was it was stuck completely closed. The coolant wasn't flowing at all and the temp gauge would go all the way up. But it wasn't overheating, maybe b/c I would only drive it a few miles at a time. And it turns out, the T-stat I put in to replace it was
....a "Fail-Safe". Why would I do that, maybe b/c it was cheap? Eh, it's over a year and still good so I'm mixed on reliability, one good and one bad.Just the same, that thing should have failed stuck open, not closed and that's consistent with what I've been reading about this particular T-Stat, but I guess it's a 50/50 deal on many of them regardless of brand. Many of them are frequently bad out of the box.
10-02-11, 09:22 AM
#35
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Sorry to put a 
on ya but less mileage would make it worse, b/c it's not being used as much opening and closing. Every T-stat that I've seen fail have always stuck closed. In 30 years I've never seen one stick open, Ive heard it happen to other people so some do. All that does is make the car run cooler and have no heat. The old days we used to take them out in the summer but now with all the computers ya can't do that anymore b/c it needs to run at a certain temp to run perfect. The one that failed on me in the 9 months only had 12K on it. But really the way I look at it is Eh, they're cheap enough to change. As long as ya catch it before something worse happens.
on ya but less mileage would make it worse, b/c it's not being used as much opening and closing. Every T-stat that I've seen fail have always stuck closed. In 30 years I've never seen one stick open, Ive heard it happen to other people so some do. All that does is make the car run cooler and have no heat. The old days we used to take them out in the summer but now with all the computers ya can't do that anymore b/c it needs to run at a certain temp to run perfect. The one that failed on me in the 9 months only had 12K on it. But really the way I look at it is Eh, they're cheap enough to change. As long as ya catch it before something worse happens.
10-02-11, 03:57 PM
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Sorry to put a on ya but less mileage would make it worse, b/c it's not being used as much opening and closing. Every T-stat that I've seen fail have always stuck closed. In 30 years I've never seen one stick open, Ive heard it happen to other people so some do. All that does is make the car run cooler and have no heat. The old days we used to take them out in the summer but now with all the computers ya can't do that anymore b/c it needs to run at a certain temp to run perfect. The one that failed on me in the 9 months only had 12K on it. But really the way I look at it is Eh, they're cheap enough to change. As long as ya catch it before something worse happens.
on ya but less mileage would make it worse, b/c it's not being used as much opening and closing. Every T-stat that I've seen fail have always stuck closed. In 30 years I've never seen one stick open, Ive heard it happen to other people so some do. All that does is make the car run cooler and have no heat. The old days we used to take them out in the summer but now with all the computers ya can't do that anymore b/c it needs to run at a certain temp to run perfect. The one that failed on me in the 9 months only had 12K on it. But really the way I look at it is Eh, they're cheap enough to change. As long as ya catch it before something worse happens.Believe it or not, I have a T-Stat that appears to be partially stuck open in the car I'm driving daily ( 1987 BMW 535i). At idle the gauge is at dead center, but while running the gauge is right outside the cool zone. It hasn't affected gas mileage or heating at this point, but I plan on swapping it out when I get a chance.
Yep, they're definitely a cheap and easy change, but my greatest fear is being on a long trip somewhere and have the thing close up on me.
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