Coolant temp issues (causing other issues?)

[jme2712]

I replaced my malfunctioning thermostat about a year and a half ago and ever since my engine hasn't been able to get near the 210 hash mark. Any ideas on why my engine won't reach optimum temps? Should I replace the sensor? Also i believe this is when my intermittent ac issue began. Could any of this be the cause?


View attachment 28744


As for air gap and ac I haven't been able to procure info on what the gap measurement should be. The only thing I've been able to do is compare it with my parents 02 envoy and the gaps appear to be the same.

I also have a bad fan clutch maybe that is causing it. I think my envoy is lemoning on me.

 

[meerschm]

you could have the wrong thermostat. should run straight up at 210 (within a needle anyway)


you should try to read the coolant temp from the OBD. if it reads ok, the thermostat would be ok, and you could just have an instrument panel issue.

i would think you would get codes from running that cold, and end up with some potential damage to the cat. do you have a check engine light?

 

[RayVoy]

Your new (last year) thermostat is either defective out of the box, or the wrong temp for the engine. The correct temp should be (if I remember correctly) 187 F degrees, a quick site search should find the correct temp.

 

[jme2712]

you could have the wrong thermostat. should run straight up at 210 (within a needle anyway)

you should try to read the coolant temp from the OBD. if it reads ok, the thermostat would be ok, and you could just have an instrument panel issue.

i would think you would get codes from running that cold, and end up with some potential damage to the cat. do you have a check engine light?

No check engine light. That's what has me confused. So most likely an instrument issue.

 

[meerschm]

does the light come on when you turn key on and start?

have you read the codes? I would want to see what the real coolant temp is.

you don't have an IR thermometer laying around, do you?

 

[jme2712]

does the light come on when you turn key on and start?

have you read the codes? I would want to see what the real coolant temp is.

you don't have an IR thermometer laying around, do you?

Yes the light works. Unfortunately I don't have anything to communicate with my car. I'm looking for a good one now.

 

[RayVoy]

Ok, I agree you could have a bad sensor, or a problem in the gauge.

Did the gauge read correctly (needle straight up) before the t-stat was changed?

The first thing you need to do is have the engine temp checked (you need one good and known constant).

 

[jme2712]

Ok, I agree you could have a bad sensor, or a problem in the gauge.

Did the gauge read correctly (needle straight up) before the t-stat was changed?

The first thing you need to do is have the engine temp checked (you need one good and known constant).

Yes it worked before the change. Just around 210 is where it always hung before the stat crapped out and overheated my engine. Any good obd's for iOS?

 

[The_Roadie]

Any good obd's for iOS?

Torque for Android (assuming you trade your phone for Android) is the best for iOS.

 

[jme2712]

Torque for Android (assuming you trade your phone for Android) is the best for iOS.

I would but i would hare to see all those purchases I've made through the AppStore since 2008 go the way of the dodo.

 

[RayVoy]

and overheated my engine.

I'm not trying to be hard to get along with, but that would have been good info to have posted in the opening post.

Cooling problems post-overheating is a completely different trouble shooting path.

As I suggested earlier, let's find out what the water temp is actually running at.

 

[jme2712]

I'm not trying to be hard to get along with, but that would have been good info to have posted in the opening post.

Cooling problems post-overheating is a completely different trouble shooting path.

As I suggested earlier, let's find out what the water temp is actually running at.

I ordered an wifi dongle to read that info and more. I'll update when I have more info. And there nothing wrong with constructive criticism.

What kind of issues would I be looking for if the coolant temp is within spec?

 

[RayVoy]

I ordered an wifi dongle to read that info and more.

Again, I'm not trying to be critical, but that won't provide the info needed. All your doing is providing a 2nd gauge. If it reads the correct temp, then the gauge is bad, but if it reads the same as the dash gauge, you still don't know what the problem is. To get the correct water temp, you need to use a known correct thermometer. An IR digital one would be ideal, but a good old fashion, dropped into the rad thermometer will work.

 

[jme2712]

An IR digital one would be ideal, but a good old fashion, dropped into the rad thermometer will work.

In that case I'll be able to do that tomorrow. I'll report my findings and we can go from there.

 

[CaptainXL]

No check engine light. That's what has me confused. So most likely an instrument issue.

Not necessarily. The PCM will believe the Coolant Temp Sensor even if it's bad. My suggestion would be to replace both the thermostat and coolant temp sensor this time around.

 

[Wooluf1952]

Not necessarily. The PCM will believe the Coolant Temp Sensor even if it's bad. My suggestion would be to replace both the thermostat and coolant temp sensor this time around.

But if the t-stat and/or temp sensor are bad, there should be a CEL. Where as if the gauge/stepper motor is bad, the PCM is getting good info and no CEL is set.
The OP needs to get the actual temp first, as RayVoy and Meerschm have stated. Unless I missed something.

 

[CaptainXL]

The OP needs to get the actual temp first, as RayVoy and Meerschm have stated. Unless I missed something.

Nope you guys are correct. I failed to read all the replies. Need to get the temp from Autozone or some other place that does free code checks. Those scanners they use should be able to read coolant temp.

 

[meerschm]

View attachment 28754

If you see your actual coolant temp is pretty close to 200 degrees f, I would drive and be happy.

here is a screen from a drive I took last year. you can see i fussed a bit with the computer attached before taking off. and the temp went from 60 to around 200 and stayed pretty much between 200 and 210.

given you had overheated the engine, I would want to find a way to measure the coolant temp, or replace the temp sensor. you need the temp as coolant leaves the thermostat.

for reference, I replaced the thermostat a few months before this, was running cool. I still have the original sensor, after ten years and just under 150,000 miles.

I use my laptop (my cell phone barely takes pictures) with obdwiz software and obdlink SX cable from scantool.net I also invested in Scan XL software, and a GM package which reads more codes not in the generic OBD set.

you may want to check out https://itunes.apple.com/us/app/dashcommand-obd-ii-gauge-dashboards/id321293183?mt=8
kind of pricy. probably cheaper alternatives in the apple app store.

 

[jme2712]

Please forgive me for lacking details on the original post. When I put the new thermostat in is when I saw the needle go into the red with in 5-10min span. I turned off the car immediately and let it sit over night I could hear boiling from the coolant overflow reservoir. Then next day it didn't over heat it ran cool at about the temp you see in the pic. The reason I changed my stat is because the engine was running about 230-240 and I could hear the boiling at this point also. I should mention that the gauge (currently) will rise 2-3 ticks and fall the same amount when I'm idling and able observe. That is all the details i can think of.

I will update on coolant temp later today.

 

[RayVoy]

Ok, good info. The good answer to your problem is that you still have air in the cooling system.

The temp spike you saw the night you changed the stat, and the bubbling sounds you heard, are indicative of trapped air. Some will slowly work it's way out, but it sounds like you still have air trapped in the system.

I'll suggest parking on a steep grade, nose in the air, and remove the rad cap. Run the engine until the t-stat opens and the pump starts to move the water. Moving the water without the system being pressurized may move the air.

The bad answer is that there may still be a problem with the t-stat, or the sensor. Let us know how you make out with the temp reading.

 

[jme2712]

Just an update until I can do a non digital measurement on the coolant temp and run on a steep grade tomorrow. I got my obdII dongle in and though dashcommand it says my coolant temp is 180F. This is after driving 15miles, letting it sit (off) for about 20 minutes while i tried to config the dongle and then letting in run for 5 min. Seams about right to me, but I'll follow up tomorrow with a real test.

 

[gmcman]

180 deg is too cold. Can't think off hand but min temp is around 186?

How hot was the coolant when it was overheated? How long did you drive it that way? Something to consider is a possible warped head and exhaust gasses entering the cooling system which would cause overheating. Would be worst case but if all else fails it's something to check. Either by a coolant pressure test (easier) or a compression test.

 

[jme2712]

180 deg is too cold. Can't think off hand but min temp is around 186? How hot was the coolant when it was overheated? How long did you drive it that way? Something to consider is a possible warped head and exhaust gasses entering the cooling system which would cause overheating. Would be worst case but if all else fails it's something to check. Either by a coolant pressure test (easier) or a compression test.

what's the downside of running 170-180? Just curious.

 

[CaptainXL]

what's the downside of running 170-180? Just curious.

Will cause the PCM to run the engine in constant enrichment mode which will reduce the life of the catalytic converter. The engine was designed to run between approximately 190F and 220F

 

[triz]

To lazy to look. But was this a factory thermostat?

 

[gmcman]

jme....you should replace the temp sensor as suggested just to be sure. This is something you should do when you change the stat since it's right there. This way you know the ECM is (or should be) receiving true signal. Your coolant could very well be at 200 ish and the ECM thinks it's cold also depicted on the gauge.