Coolant thermostat/temp questions

[meerschm]

I have noticed that my temperature gauge (for what it is worth) has been running about a quarter to the vertical during the colder temperatures this winter. It does not jump around or vary with coasting or acceleration like others have noted, but will not warm all the way up to normal on my stop and go commute in the cold weather. Since this has been happening, the heat has not been getting as hot as usual either. Does it sound like a thermostat and radiator fluid change to you guys? That's what I'm understanding from reading this thread. Oddly, SEL just popped on this morning (a day or two after the arctic vortex).

You need to read the error code that made the light come on.

a low thermostat will do the trick. my CEL came on, and then I noted the temp gauge was a couplt ticks to the left of center. I initially troubleshot mine by signing up for Onstar for a bit (having had the hardware upgraded to allow such an option) they read the code while I kept driving..(which let me continue the six hour drive i was on with my wife)

a local auto parts place can read the error code for you too.

Knowing what I do now, I would get it changed as soon as possible you'r mpg will suffer, and if left too long, will eat the cat. $$$$$

 

[meerschm]

Can you do this again please? Only this time note the outside temp and let the truck idle until it warms up fully. My engine is taking a long time to heat up. I think its a stuck open thermostat but there doesn't seem to be any definitive tests other than comparing with a known good.

That graph starts at coolant temp of 59 degrees, which was ambient if I recall. can't find the original log file right now.

the slope is pretty constant, (not changing with the mph speed) on the temp graph until the themostat opened around 200 degrees, which happened 6 or 7 minutes into it.



it has warmed up here a bit, so may not satisfy your need.

my current temp outside is 40, and I drove it just before lunch so it is likely still a bit warmed up.

I will run some data and see what it looks like.

should be able to update later tonight.

do you have a way to read the OBD temp?

 

[Marksman762]

I have noticed that my temperature gauge (for what it is worth) has been running about a quarter to the vertical during the colder temperatures this winter. It does not jump around or vary with coasting or acceleration like others have noted, but will not warm all the way up to normal on my stop and go commute in the cold weather. Since this has been happening, the heat has not been getting as hot as usual either. Does it sound like a thermostat and radiator fluid change to you guys? That's what I'm understanding from reading this thread. Oddly, SEL just popped on this morning (a day or two after the arctic vortex).

Based on the above - yes that sounds like a stuck open thermostat. That said - get your code scanned when you can, that will tell a lot. It could be completely unrelated.

So long as you're on the road long enough (10 minutes+) you should warm up to operating temp regardless of the recently cold temps. I've been in -25F for the last week and I warm up to slightly above the 210 mark after my thermostat change.

 

[CaptainXL]

do you have a way to read the OBD temp?

Yes. I can heat up the garage to whatever temp you might have locally. I will just monitor the coolant temp and start it once it reaches. So test should be similar.

 

[hullman8]

Based on the above - yes that sounds like a stuck open thermostat. That said - get your code scanned when you can, that will tell a lot. It could be completely unrelated.

So long as you're on the road long enough (10 minutes+) you should warm up to operating temp regardless of the recently cold temps. I've been in -25F for the last week and I warm up to slightly above the 210 mark after my thermostat change.

Thanks, I'll stop and get it read on my way home from work tonight. Just thought I'd check to see if my gut was lying to me. Mine will not get up to normal operating temp when it's in the 30's outside during a stop and go commute (roughly 30 mins).

 

[meerschm]

View attachment 31976

I gave up after ten minutes.

ambient was 40 degrees, but the coolant temp was not that cold.

you can see the rise started to taper off, and was not uniform before I started to move.

(I figured the graph should give you enough for comparison)

I was in the shade in a parking garage. I have full synthetic oil in the crankcase. I had the heater set on low fan, but auto mode, and had the drls on.

View attachment 31977

this is up until I gave up and headed on the road. you can see the coolant was at 57 degrees when I started. the first 30 seconds or so are with the engine off. you can see the temperature rise started to taper off.

if I get ambitious, perhaps I will do this again in the morning. we are supposed to have freezing rain.

 

[meerschm]

View attachment 31986

Outside temps around 35 degrees. started after a minute or so and waited for 11 more minutes..

heater mode set to floor, second tick up on fan speed, DRLs on, and radio.

it was raining and there was some ice on the driveway.

below includes the drive out of the neighborhood. You can see that once I start moving, the temp comes the rest of the way up to thermostat operation pretty quick.

View attachment 31987

 

[mykals1]

I replaced my t-stat with a stant obd scanner reads 198 deg. is this enough heat in engine to come off rich burn or should I get it up to 210 with a gm stat

 

[meerschm]

I replaced my t-stat with a stant obd scanner reads 198 deg. is this enough heat in engine to come off rich burn or should I get it up to 210 with a gm stat

I think you are ok.

 

[Sparky]

198 is fine. I think 190 is the minimum, and if it was bumping that I'd be concerned.

Mine runs 195-ish, always has since I got it.

 

[mykals1]

thanks glad to hear,just passed nys emissions inspection and after chasing trouble codes for the past week be nice to enjoy it now

 

[fj4072]

Yeah wasn't there one year that the coolant sensor was on the back of the engine or something really weird? I seem to remember someone on here or the OS trying to find his sensor and no one believed him that it wasn't next to the tstat at first.

On my 06' TB SWB I6 I bought the Stant T-Stat 195 degree and the sensor since it was "right there". Nope, it's not there, my sensor is on the very back of the engine on the passenger side. Anyone have any pics of how to get to this PITA sensor and change it out? T-stat was pretty easy with ratcheting wrenches, alternator removed and battery/tray removed. However, this darned coolant sensor got to me, can't see how to get to it. Any help is appreciated.



P.S. Wow was I wasting gas & $ running that old stuck open t-stat (steady 180)...much better MPG now running 195+ degrees.

 

[IllogicTC]

On my 06' TB SWB I6 I bought the Stant T-Stat 195 degree and the sensor since it was "right there". Nope, it's not there, my sensor is on the very back of the engine on the passenger side. Anyone have any pics of how to get to this PITA sensor and change it out? T-stat was pretty easy with ratcheting wrenches, alternator removed and battery/tray removed. However, this darned coolant sensor got to me, can't see how to get to it. Any help is appreciated.



P.S. Wow was I wasting gas & $ running that old stuck open t-stat (steady 180)...much better MPG now running 195+ degrees.

Yeah, that's something we're working on... the "do them both in one shot" job claim only applies to 02-05 engines.

As I have an 05, the best I can say right now is to try searching. I know others have had the same problem.

 

[Playsinsnow]

...However, this darned coolant sensor got to me, can't see how to get to it.

Anybody else replace the ECT Sensor on a 2006 or newer truck with the 4.2L? What a pain!!! Passenger side, back of the block. 15mm, and I couldn't find a proper sensor socket anywhere, so I had to slit a deep 15mm socket to get it done. Took a long time to get the old one out and then the new one in.

Not one of GM's better ideas.

I second the search idea, trailvoy?

 

[dmanns67]

198 is fine. I think 190 is the minimum, and if it was bumping that I'd be concerned.

Mine runs 195-ish, always has since I got it.

Maybe its time for a new t-stat on my TB. Mine rarely hits 190*. Usually in between 183*-189* while I am driving. If I am sitting idle it will hit 190*, but never past.

 

[CaptainXL]

Maybe its time for a new t-stat on my TB. Mine rarely hits 190*. Usually in between 183*-189* while I am driving. If I am sitting idle it will hit 190*, but never past.

I have seen this before. And IMHO if you are in the 180's then its time for new stat.

 

[dmanns67]

I have seen this before. And IMHO if you are in the 180's then its time for new stat.

After reading through this thread, it would appear that I am running on the low end of the temp. This might help my MPG as well . Since I do not have an CEL hopefully I caught it soon enough before any further damage. Might as well replace the cooling system temp sensor too. Both parts appear to be under $20 via rockauto.com.

 

[fj4072]

After reading through this thread, it would appear that I am running on the low end of the temp. This might help my MPG as well . Since I do not have an CEL hopefully I caught it soon enough before any further damage. Might as well replace the cooling system temp sensor as well. Both parts appear to be under $20 via rockauto.com.

Rockauto is the best, that's where I went. Looking at your profile, you have an 07'.....you need to change the sensor....take one for the team with pics? Playsinthesnow, I followed all of you here to GMT, so don't frequent tv, BUT there was a write up on it. While the pics were a little vague, did give me a better idea, maybe I won't have to pull the engine after all. Thanks!

 

[JerryIrons]

On my 06' TB SWB I6 I bought the Stant T-Stat 195 degree and the sensor since it was "right there". Nope, it's not there, my sensor is on the very back of the engine on the passenger side. Anyone have any pics of how to get to this PITA sensor and change it out? T-stat was pretty easy with ratcheting wrenches, alternator removed and battery/tray removed. However, this darned coolant sensor got to me, can't see how to get to it. Any help is appreciated.

I had the exact same plan, bought the sensor and was planning to change it as well. Surprise! I took one look at that location and said F that, I will change the thermostat and see how it runs. The sensor is still in the box in my garage.

 

[jes1888]

On my 06' TB SWB I6 I bought the Stant T-Stat 195 degree and the sensor since it was "right there". Nope, it's not there, my sensor is on the very back of the engine on the passenger side. Anyone have any pics of how to get to this PITA sensor and change it out? T-stat was pretty easy with ratcheting wrenches, alternator removed and battery/tray removed. However, this darned coolant sensor got to me, can't see how to get to it. Any help is appreciated.



P.S. Wow was I wasting gas & $ running that old stuck open t-stat (steady 180)...much better MPG now running 195+ degrees.

I had the exact same plan, bought the sensor and was planning to change it as well. Surprise! I took one look at that location and said F that, I will change the thermostat and see how it runs. The sensor is still in the box in my garage.

The most efficient method to remove the coolant sensor on 06 + up is to buy or use and old one 15mm long socket, preferably for a 3/8 ratchet so it takes less space, take a grinder and cut a 1" or 1 1/2" strip on the socket for the sensor cable, like an o2 sensor socket. That'll be your best bet, that's the way i did it after spending the evening before cursing GM for that bad move. Good luck!!

 

[meerschm]

I too, purchased a temp sensor, and decided to leave it off the vehicle. mine was easier to access while doing the thermostat, but I figured there was no good reason to open up the system for a problem not there.

the original sensor is fine. as long as it is intact, and the wires have not corroded or broken off, there is not a real need to change it. just because if has six flats does not mean a wrench has to be applied

the thermostat has parts that move and wear. the sensor has no moving parts.

 

[JerryIrons]

I agree. It seems these days the new parts that you buy may not last as long as the old part that is still on there working fine.

 

[CaptainXL]

Really its not that hard to replaced the coolant temp sensor. Just need a crows foot adapter to a socket wrench to put it back on. It was $5 for a set a Harbor Freight.

 

['03EXT]

Sensors go bad as well, and can send back incorrect info to PCM , which in turn adjusts for the incorrect reading, it happened to mine , if u have any doubts and u are in there already to do the thermostat ( on earlier models) the ease of the change out and ease of price is a no brainer

 

[jes1888]

I too, purchased a temp sensor, and decided to leave it off the vehicle. mine was easier to access while doing the thermostat, but I figured there was no good reason to open up the system for a problem not there.

the original sensor is fine. as long as it is intact, and the wires have not corroded or broken off, there is not a real need to change it. just because if has six flats does not mean a wrench has to be applied

the thermostat has parts that move and wear. the sensor has no moving parts.

Still, the sensor seems a little crappy, i bought mine thinking it was near the thermostat too, but then it was on the other side of the block. I still changed it with the method i stated before and they tend to corrode on the tip, leading to wrong readings, or gauges going up and down. If yours is working fine, leave it like that if you want, however, when it's time to change it use the method stated before. cheers

 

[Machoman]

Where is the Temp sensor located? My torque app say my temp is 179-180.

 

[Robbabob]

Where is the Temp sensor located? My torque app say my temp is 179-180.

That is too low!!!! you're also in need of a new t-stat.

 

[CaptainXL]

That is too low!!!! you're also in need of a new t-stat.

Your too low. Pull up!

 

[Blckshdw]

Where is the Temp sensor located? My torque app say my temp is 179-180.

If you follow the radiator hose on the drivers side up to the engine, that takes you right to the thermostat. For your MY truck, the temp sensor is right next to it.

 

[jes1888]

Where is the Temp sensor located? My torque app say my temp is 179-180.

If you follow the radiator hose on the drivers side up to the engine, that takes you right to the thermostat. For your MY truck, the temp sensor is right next to it.

Correct, the temp sensor should be near the thermostat. If it aint there, then it's like in mine, on the passenger side, behind the manifold, near the firewall Good luck