Running Too Cool?

[eray2371]

Taken on the highway, at about 70mph, 2hrs into the trip and it was in the mid to high 50s. 113,000miles on the odometer.

Is Snow White running too cool?

 

[Mounce]

Got any codes? Might be time for a thermostat or ECT sensor.

-voltage is low too. Ever worked on the cluster? Needles might be out of spec.

 

[Daniel644]

YES, assuming the gauge is functioning properly (it's stepper motor can begin failing and give false readings just like the others), check it with a scan tool with live data to confirm, odds are thermostat went out and is stuck in the open position.

 

[Mounce]

That's not the typical behavior of a bad stepper motor though. Normally, when they go bad, they don't go to zero when key is turned off then it reads too high when you start her back up.

 

[coolasice]

Got any codes? Might be time for a thermostat or ECT sensor.

-voltage is low too. Ever worked on the cluster? Needles might be out of spec.

Voltage is normal for an 07. Most likely a tstat at issue...

 

[bobdec]

My guess is your at 175-180* not low enough to set a code (165* I think) or cause problems, I'd replace T-Stat as engine is happier above 185*. Was the coolant replaced at 100K miles. if not T-Stat change is a good time to do that.
Voltage is OK, indicates you are in energy saving mode, the '07 has battery management and lowers alternator to 12.5 volts under low loads on highway driving. The voltage gauge should indicate straight up, or a bit to the right (14 volts) after a start-up and running around in normal city driving.

 

[dmanns67]

You need an ELM327 and the TorquePro app so you can read live data. Those gauges are a waste of time. The coolant temp never runs at 210° to begin with. Usually around 194° with a functioning tstat.

You do not need a code to change the tstat. Using the ELM and app is how I figured out my tstat was getting stuck open. Never seeing temps above 183°.

98% of the time, the issue is with the tstat, but it is highly recommended to change out the ECT sensor with the tstat. Sensor is right above the tstat. You can get both parts off of rockauto.com for around $20 each.

 

[coolasice]

You need an ELM327 and the TorquePro app so you can read live data. Those gauges are a waste of time. The coolant temp never runs at 210° to begin with. Usually around 194° with a functioning tstat.

You do not need a code to change the tstat. Using the ELM and app is how I figured out my tstat was getting stuck open. Never seeing temps above 183°.

98% of the time, the issue is with the tstat, but it is highly recommended to change out the ECT sensor with the tstat. Sensor is right above the tstat. You can get both parts off of rockauto.com for around $20 each.

Don't know about 07, but my 08 has the ECT sensor at the back of the engine.. nowhere near the tstat. I did not change it when I did my tstat.

 

[dmanns67]

Don't know about 07, but my 08 has the ECT sensor at the back of the engine.. nowhere near the tstat. I did not change it when I did my tstat.

06-09 ECT sensor was moved to the passenger side of the engine near the firewall, huge PITA to change. 02-05 the ECT sensor is near the tstat on the driver's side of the engine. I am on tapatalk so I cannot see the OPs vehicle information.

 

[eray2371]

2007 4.2l L6
No illuminated CEL

The voltage is fine, like someone commented earlier, it's computer controlled and decreases depending on load.

I probably should just go ahead and change the t-stat, I bought one a year ago when I changed the wp and fc....

 

[Kurb]

06-09 ECT sensor was moved to the passenger side of the engine near the firewall, huge PITA to change. 02-05 the ECT sensor is near the tstat on the driver's side of the engine. I am on tapatalk so I cannot see the OPs vehicle information.

Hmm.. So that's where it is... I bought an ECT sensor when the thermostat stuck open last year on my 2006 TB, and I saw posts that the sensor was beside the thermostat. I never replaced the sensor since replacing the thermostat fixed my problem, and the thermostat took longer than it should have since GM did a good job hiding it. You have to remove the alternator to get to it. I did have the P0128 code, though.

 

[coolasice]

Hmm.. So that's where it is... I bought an ECT sensor when the thermostat stuck open last year on my 2006 TB, and I saw posts that the sensor was beside the thermostat. I never replaced the sensor since replacing the thermostat fixed my problem, and the thermostat took longer than it should have since GM did a good job hiding it. You have to remove the alternator to get to it. I did have the P0128 code, though.

I did the same thing although I never had the code thrown for it. Never did the ECT sensor... had no reason to.

 

[dmanns67]

That why I was suggesting some tool to read live data so you can see what the ECT is actually reading. Using the Torque app, I too seen I was running too cool and changed the tstat before any CEL came.

With the 02-05 it is recommended to change the tstat and ECT together due to location, price of parts, and coolant loss. More of an added preventive maintenance activity.

06-09, I would not worry about the ass pain of the ECT sensor replacement.

 

[eray2371]

Just finished my 250mi trip home....kept an eye on the torque app and it's running about 173 degrees at highway speeds. So I'd say there's no urgency in putting the t-stat on. Thanks for all the input gentlemen!

 

[coolasice]

thats how mine was before changing tstat.. 175-183... after changing i get 190-195

 

[littleblazer]

After they replaced mine (160ish) it currently runs 196-201 at 20 degrees and 70mph. You're going to burn a bit more fuel running colder too I believe.

 

[Denali n DOO]

I wouldn't be happy with 173, I'd change it. Think it can mess up the cat too...

 

[dmanns67]

After they replaced mine (160ish) it currently runs 196-201 at 20 degrees and 70mph. You're going to burn a bit more fuel running colder too I believe.

You are correct sir. In the end, by ignoring a failing tstat you could end up clogging your cat due to the engine burning more fuel and trying to run hotter since the optimal temperature is not being seen at the ECT sensor.

Thats why the SS guys swap out their OE tstat for a 160* tstat. More HP yo. #becauseracetruck

 

[djthumper]

Just finished my 250mi trip home....kept an eye on the torque app and it's running about 173 degrees at highway speeds. So I'd say there's no urgency in putting the t-stat on. Thanks for all the input gentlemen!

I would definitely change it out. I noticed an improvement when I changed mine.

 

[Tinman204]

My gauge was sitting at the same spot. I hooked up a scan tool and my temp was sitting at 180. I changed the thermostat and now it runs at 200 to 204 on a warm day. Fuel mileage also went way up now that she's running warmer to.

 

[DocBrown]

I wouldn't be happy with 173, I'd change it. Think it can mess up the cat too...

Yep! This is what happened to mine. If had only only known at the time that running a little cool would cost me that much money and work...

 

[SnowBlazer]

I just noticed that my T Stat needle only gets to about 1/4 of the way up.

I'll grab some pictures here in a bit

View attachment 67278

View attachment 67279

 

[Robbabob]

I just noticed that my T Stat needle only gets to about 1/4 of the way up.

I'll grab some pictures here in a bit.

SB, do a scan and make sure. Sure sounds like you have yours stuck open, and need to replace it asap.

 

[SnowBlazer]

SB, do a scan and make sure. Sure sounds like you have yours stuck open, and need to replace it asap.

Will do...she's parked now, so I'll probably run by AutoZone later and borrow their scanner. Only thing is, is that she's my DD so I'll have to drive it until I can get that part.

And it looks like TapaTalk doesn't want to upload my photos

 

[Robbabob]

No photo necessary. If it's at 1/4, it's way too low. Also, since it's at 1/4, the stepper motor should be working and probably giving you the correct reading.

Sounds like it's time to replace the temperature sending unit (I can't remember what's it's called, exactly), since you have an '02 and it is right in there near the t-stat. PIA to get to, so change them both at the same time.

Pretty sure all this information is spot on.

Good luck!

 

[dmanns67]

Will do...she's parked now, so I'll probably run by AutoZone later and borrow their scanner. Only thing is, is that she's my DD so I'll have to drive it until I can get that part.

And it looks like TapaTalk doesn't want to upload my photos

How have you not bought a code reader yet Buy an ELM327 and download the torque app. For $25 you can read and clear codes. You can also see live data which would show you what your coolant temp is actually is.

 

[Robbabob]

For $25 you can read and clear codes.

I haven't found where I can clear codes, but I certainly can read them. Probably just my bad learning curve. I'll have to leave my gas cap off so I can throw a code.

SB needs to get with the program on the ELM, though, for sure.

 

[SnowBlazer]

SB needs to get with the program on the ELM, though, for sure.

I Have an iPhone so would EngineLink work? Also, are the blue ones like these any good? http://pages.ebay.com/link/?nav=item.view&alt=web&id=231076061631

 

[Robbabob]

iGadgets require wi-fi, Android uses Bluetooth. They are not interchangeable.

Edit:Says it's good for either... Here. For under $17, damn good price.

Edit 2: I believe your app will cost you more than the Torque app does. Damn iDevices.

 

[SnowBlazer]

That's what it looks like after about 30 minutes driving her in 30*F weather.

 

[Robbabob]

Yep, the t-stat is not doing its job properly. It is either stuck open, or prematurely opening before temp setpoint.

That is very bad for your Cats and gas mileage. Don't put off this repair too long or you'll be buying a cat too.

Good luck!

 

[SnowBlazer]

Ok. So, it's just the T-Stat that I need? And what's the part number? I'll get it on order today.

 

[Robbabob]

You get to decide from where to buy, and your choice of videos on the replacement. I've no clue which manufacturer.

Remember, you'll want to replace the temperature sensor, too. Guessing Delphi is key for choice, here.

 

[SnowBlazer]

Thanks Robb! The only thing that puzzles me is the fact that I have no dash lights and my gas mileage is actually pretty normal. I average 15 with minimal highway driving.

 

[Robbabob]

yer welcome

Get a scan tool, or get to one, and verify via the OBDII plug. At that apparent temperature, you should have gotten a code; less than 180° F I think I read.

Call around to your parts stores and see who will scan you for free. They should carry everything you need for the repair. Buying from them shows your appreciation for the free scan.

 

[djthumper]

You may not necessarily need the temp sensor. I would change out the thermostat and leave it at that, unless you are still having issues.