Thermostat quality

[mechtech2]

Bad luck is bad luck.
A cheap thermostat may last 15 years, or a few months.
Our best bet is to get the best we can - it is not a wallet breaker.

 

[Gary Allan]

I really think that the only difference is in quality control. That is, they're the same thermostats. It's just that no one is rejecting the rejects. They're QC'd in the field. I don't think that a SuperStat uses any other method to open and close than a non-SuperStat.

 

[Cup of Joe]

Originally Posted By: jstutz
Originally Posted By: TaterandNoodles
I've had 2 new vehicles end up over heating when the OEM thermostats stuck shut. The last one a 08 mazda5 had less then 5k miles at the time.

I just had to change the thermostat in my Grand Caravan before christmas when I noticed it was running cold. When I pulled the old stat out it had broken the frame holding the stat together on one side so it would never fully shut.


what did you replace them with?


Both have been replaced under warranty at the respective dealers. One of the 2 failed while on a trip out of town, the other was local. The manufacturer paid for a tow over 60 miles to the dealership I had bought the car from and wanted it to be repaired at.

I am not going to repair anything on a new car that is only a couple of months old. I've had the Mazda nearly 2 years now so I would not have a problem replacing the stat at this point.

 

[andyd]

I paid 21$ for after mkt t'stat for my car 9 yrs ago and it works great. I think it is the first one I ever changed. I spent my formative yrs driving aircooled Bugs. Can you buy a t'stat that can only fail open?

 

[OVERKILL]

Many aftermarket T-stats are of the fail-safe variety, that are only supposed to fail open.

 

[artificialist]

This thread also discussed T-stat problems:
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1696774#Post1696774

 

[cchase]

How do you guys know if the car is running too cool? I was under the impression that the gauges in cars are notoriously inaccurate.

Just wondering. I keep replacing the t-stat in my truck and still the gauge never makes it up to where it used to sit, it sits at 160 degrees instead of the 195 it's supposed to be at. After replacing them twice I assumed the CTS was just whacked out from where it was.

I know how to test if a t-stat is working at the right temp but without pulling it how can you tell, I guess is my question.

 

[Quest]

Simple! take it out on a highway run where the wind gushes through your radiator with enough velocity to cool your engine coolant temperature down. As a result: when you put your internal compartment temperature up to high, you heated air becomes cooler as time goes by (until it's very cool/not enough heat to warm your compartment).

 

[mechanicx]

If you had a scanner and it says for example 195F and your instrument panel is saying 160, then you know it's inaccurate. a lot of times the CTS is also used for the gauge.

 

[jstutz]

Originally Posted By: cchase
How do you guys know if the car is running too cool? I was under the impression that the gauges in cars are notoriously inaccurate.

Just wondering. I keep replacing the t-stat in my truck and still the gauge never makes it up to where it used to sit, it sits at 160 degrees instead of the 195 it's supposed to be at. After replacing them twice I assumed the CTS was just whacked out from where it was.

I know how to test if a t-stat is working at the right temp but without pulling it how can you tell, I guess is my question.


I just know from having the vehicles for a long time and paying attention to where the gauges normally sit in each vehicle. On the other hand, i have a 93 C1500 with 217k miles on it and i have changed the Tstat twice and the coolant temp sensor by the thermostat twice and that gauge is set at 165F. I think it is just a bad gauge or something because if the tstat and the sending unit is working, the engine should be 195 and reading something close too it.

 

[cchase]

Originally Posted By: jstutz
I just know from having the vehicles for a long time and paying attention to where the gauges normally sit in each vehicle. On the other hand, i have a 93 C1500 with 217k miles on it and i have changed the Tstat twice and the coolant temp sensor by the thermostat twice and that gauge is set at 165F. I think it is just a bad gauge or something because if the tstat and the sending unit is working, the engine should be 195 and reading something close too it.



So you have the same truck, same problem and the gauge is sitting in the same spot... interesting.

 

[cchase]

Well, this has nothing to do with the original thread, but for the past 2 days I've been trying to fix this inconsistency I mentioned earlier.

I replaced the coolant temp sensor and still the gauge sits at 155 degrees. I checked operation of the gauge by shorting the connection, goes full up - good, I checked the ground of the sensor, good, the ohms at 195 degrees is 255 which seems correct, the voltage to the sensor is correct. All signs point to the gauge itself being the culprit, so tomorrow the cluster is coming out to be checked out.

 

[440Magnum]

Get a Mr. Gasket / Robertshaw balanced thermostat. The only one worth using, IMO.

 

[demarpaint]

Originally Posted By: cchase
Well, this has nothing to do with the original thread, but for the past 2 days I've been trying to fix this inconsistency I mentioned earlier.

I replaced the coolant temp sensor and still the gauge sits at 155 degrees. I checked operation of the gauge by shorting the connection, goes full up - good, I checked the ground of the sensor, good, the ohms at 195 degrees is 255 which seems correct, the voltage to the sensor is correct. All signs point to the gauge itself being the culprit, so tomorrow the cluster is coming out to be checked out.

Did you check the operation of the T-Stat to see if it opens at the temp it was designed to open at? There is a chance that the t-stat is opening up at the wrong temperature. I would check the t-Stat operation first if you haven't done so before I pulled an instrument cluster. They can easily be checked by heating them up in a pot of water and seeing what temp the water is at when the t-stat opens. JMO

 

[oldmaninsc]

Originally Posted By: demarpaint
Originally Posted By: cchase
Well, this has nothing to do with the original thread, but for the past 2 days I've been trying to fix this inconsistency I mentioned earlier.

I replaced the coolant temp sensor and still the gauge sits at 155 degrees. I checked operation of the gauge by shorting the connection, goes full up - good, I checked the ground of the sensor, good, the ohms at 195 degrees is 255 which seems correct, the voltage to the sensor is correct. All signs point to the gauge itself being the culprit, so tomorrow the cluster is coming out to be checked out.

Did you check the operation of the T-Stat to see if it opens at the temp it was designed to open at? There is a chance that the t-stat is opening up at the wrong temperature. I would check the t-Stat operation first if you haven't done so before I pulled an instrument cluster. They can easily be checked by heating them up in a pot of water and seeing what temp the water is at when the t-stat opens. JMO


I agree. Especially on vehicles where the thermostat is difficult to get to - I do the pot of water trick FIRST. I've seen too many thermostat out of the box that were defective.

 

[cchase]

Thermostat works correctly.

My last ditch effort now is pulling the needle off the gauge and then putting it where I know the temperature to be.

 

[jstutz]

Originally Posted By: cchase
Originally Posted By: jstutz
I just know from having the vehicles for a long time and paying attention to where the gauges normally sit in each vehicle. On the other hand, i have a 93 C1500 with 217k miles on it and i have changed the Tstat twice and the coolant temp sensor by the thermostat twice and that gauge is set at 165F. I think it is just a bad gauge or something because if the tstat and the sending unit is working, the engine should be 195 and reading something close too it.



So you have the same truck, same problem and the gauge is sitting in the same spot... interesting.


No, i have three of the same trucks (relatively). The blazer no longer has a problem, the TStat fixed it. My white 1500 still has the problem after i replaced the Tstat and Temp sensor by the thermostat housing.

 

[jstutz]

Update: I replaced my blazer Tstat with a superstat and it fixed the problem. Runs exactly where it should now. I bought another Tstat for the 1500, superstat, and it still reads 155 on gauge. I replaced the Temp Sensor up by the thermostat housing. The Gauge is still at 155. After some more research i found that the sensor that controls the gauge is not the one by the thermostat, but the one down on the block. I have that sensor here now and will get it in here in a few days. Im think that should fix it.

 

[cchase]

I already PM'ed you back, but for others...

I have replaced both of the sensors and measured their outputs which appear to be in the correct range for the coolant temperature. The thermostat operates correctly, the sensors are operating correctly, and yet the gauge still reads incorrectly.

I tried moving the needle manually to set it in the right spot but of course this offsets the "cold" temperature so that it sits at 120 degrees when the engine is cold... not acceptable in my book.

The gauge is not controlled by a stepper motor and appears to be either a current or voltage controlled gauge so clearly something else is going on here. There are no limit stops to the travel of the needle, it can rotate 360 degrees.

The plot thickens.

 

[wiswind]

cchase, seeing that you live in New England, if your temperature was really 160 instead of 195, you would notice the decreased temperature of your heat from your heater.
My father sold me his 2003 Sienna, and mentioned that just before I got it that he noticed that the heater was "not as hot as it used to be".
I connected my ScanGauge to the OBDII port and see a temperature as reported to the PCM (usually a different sensor from the Gauge sensor) of 166-168 degrees when the factory thermostat is rated at 180 degrees.
That tells me.....along with a heater that is not as hot as it used to be......that my thermostat is on the short list.
Not serious enough to mess with until the weather warms up (for me to work on it).
Those of us in cold winter country can do a reality check......with the heater to determine if our temperature is truely colder.....or if it is a sensor/gauge issue.
I agree with you.....I like the gauge to work as it should......that is what it is there for....so we can know that particular bit of information about our vehicle.

The Toyota factory manual has you test a thermostat by removing it from the vehicle....putting it into a pot of water on the stove.....with a thermometer.....and says that a 180 degree thermotst should start opening around 176 degrees.