Thermostats..

[JesseH]

Does anyone else have a problem with their thermostat going bad often? It seems as if I have to change mine every year or two before I start having a problem with it. I've always ran toyota red coolant and toyota thermostats... I did try a parts store one and that only lasted about a year. Maybe I just have bad luck with these?::shrug::

 

[jetjock]

Define "having a problem with it".

 

[Poodles]

Water cooled turbo?

If not, did you block off the lines or loop them?

 

[JesseH]

Water cooled turbo?

If not, did you block off the lines or loop them?

They just start sticking, they start staying open and running cooler than normal then every once and awhile stick closed for a small duration enough for the temp gauge to start rising.

Non- water cooled turbo, the lines are looped as they should be, even when I was running my 60-1 that was water cooled I still had the same issue.

 

[planemos]

An easy way to test it is take the t stat out. Put it in a pot of water. Turn on stove and heat. If it doesn't crack open after heating it up a lot then you know it's bad.

 

[JesseH]

An easy way to test it is take the t stat out. Put it in a pot of water. Turn on stove and heat. If it doesn't crack open after heating it up a lot then you know it's bad.

I know it's bad, I'm just a little puzzled why they keep going bad every year or two.

 

[te72]

Can't say I've ever had one that went bad on me, but I don't put many miles on my cars either. Always a good idea to test them before you put them in though, just so you're sure it works.

 

[Compton74]

is your cooling system completely stock besides the looped over line?

 

[3p141592654]

The first problem I had with my Supra was a stuck thermostat. It was 1997, so the original lasted 7 years. Haven't had any problems since.

 

[JesseH]

is your cooling system completely stock besides the looped over line?

No, I have a 3 row aluminum radiator, and everything else that is stock in the cooling system has been replaced with OEM toyota parts (minus the heater core)... and the car has never had any form of a leak sealer or any additives in it. This has been an on going thing for the last 4 or 5 years all the way from when I swapped out the GE for the GTE. It's not like I put a stat in it and it's bad, they end up going bad every two years or so, with exception for the Stant one I tried once and that one only lasted a year. When I drain the coolant is still a nice red color with no traces of rust or anything of that sort.

It's not that I mind changing them, I would just like to know some sort of reason for it.

 

[Poodles]

Color of the coolant really doesn't show much, you have to test it.

Though i doubt it's your issue. How often do you drive the car? Maybe it's sitting for prolonged periods of time?

Also, why do you think it's the thermostat? Could be any number of things that are "solved" or masked simply in the act of replacing the thermostat.

 

[Compton74]

This may be a stupid suggestion but have you changed the radiator cap, it is not very likely but if it is not releasing the pressure at the specified temperature and the pressure builds up too high the water (coolant) won't circulate, i know you never mentioned your car overheating but this is kind of a cheap way to ensure it is working properly.

Id also make sure your fan clutch isn't showing any signs of going out, it will still work but slowly go out an not be as effective.

just trying to throw some suggestions out. Hope the problem gets fixed.

 

[3p141592654]

You need to verify the thermostat is bad, not just base it on symptoms at the engine level. An infant failure once in a while is believable, but on a regular basis is very hard to imagine. Next time you determine it to be bad, test it in a pot of water. You may well have another problem.

 

[jetjock]

.....they start staying open and running cooler than normal...

I'm still trying to figure that one out...

 

[JesseH]

Color of the coolant really doesn't show much, you have to test it.

Though i doubt it's your issue. How often do you drive the car? Maybe it's sitting for prolonged periods of time?

Also, why do you think it's the thermostat? Could be any number of things that are "solved" or masked simply in the act of replacing the thermostat.

I'm still trying to figure that one out...

The most it has sat over the summer has been a month tops, normally I drive it at least once or twice a week.

JJ, Like I said this is a rather odd one to me also.. the thermostat would stick, get up to operating tempature for 20 min or so then randomly drop three or four marks, come back up to operating tempature for awhile then the temp would climp a couple marks.

Now, before I changed the thermostat, I bought a new radiator cap from toyota along with a tempature sensor... that did not change anything. I then did a compression test and the numbers were 150 across the board on a cold motor. I changed the themosat last Saturday and have driven the car to work all week and the tempature makes it to operating tempature and stays there and has not fluxuated at all.

 

[jetjock]

The problem is a "stuck" open stat would not make the engine run cooler. That you seem confused about how the cooling system works (fwiw you're far from alone) makes it that much more difficult to resolve the issue from afar.

 

[te72]

Really hate to point the finger to *that* potential issue, but have you tested your coolant for exhaust gasses? I've seen that cause temperature irregularities. For what it's worth, the 'middle' of the stock temp gauge has a wide range of temperatures that it considers 'normal'. I believe (from monitoring my numbered gauge with the probe in the water neck) that 'normal' on the stock starts around 150 or so, so to drop below that...

Possible wiring issue a potential culprit?

 

[Poodles]

Not to mention the cooling system will fluctuate a bit for various reasons. If you're going off the stock guage you're a bit blind here...

 

[Mikael_7m]

The problem is a "stuck" open stat would not make the engine run cooler. That you seem confused about how the cooling system works (fwiw you're far from alone) makes it that much more difficult to resolve the issue from afar.

Wouldn't a stuck open thermostat cause the coolant to continue flowing through and have the engine run cooler than operating temp? I had an old worn thermostat that was effectively 'always open' which had my motor taking ages to warm up and hovering around the 65-70 degrees celcius mark....

 

[jetjock]

Longer to warm up is not the same as cooler.