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2012 1.8L overheating (or is it?)

12K views 32 replies 7 participants last post by  N8ECH 
#1 ·
Good Tuesday morning:
I find myself a bit frustrated with our daughter's 2012 LS, that has just turned 83K. We have had it a little over a year, and other than the well known plastic T stat assembly leak, it has been problem free. At present, the dash coolant temp gauge says that engine temps are good, but the dash info display is telling quite another story.
The display advises that engine temps are running from 225-245.

I have replaced the radiator temp sensor with no change. The engine temp sensor was changed along with the T stat when the plastic coolant pipe was replaced with the nicer aluminum unit. At times, the A/C would shut down along with the "AC off engine temp too high message." This has not reappeared since the radiator sensor was changed.

The dex cool has been replaced with some good gold colored G0-5 coolant. From what I have read, it can be a PIA to get the air out of this cooling system. I am aware of the bleed screw on the top pass side of the radiator. Any helpful hints for this process would be very much appreciated.


TIA Don
 
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#2 · (Edited)
The display advises that engine temps are running from 225-245.
I want to say that's within the designed operating range. The spec for the (stock) thermostat is that it's supposed to be fully open at 243°F. [Edit: Spec is 248°F for fully open.]

The one thought I have is that maybe the radiator fan is not kicking in when it should. The resistors in the fan speed control section are known to go bad. There are two: one for low, one for medium. If the medium speed resistor is bad, and the fan doesn't come on when it should, the engine will get a bit warmer until the high speed setting is finally chosen by the ECM.

If you're worried about it, you can test the fan by disconnecting the fan connector, and jumpering +12V to each of the 3 speed pins with pin 1 (where the black wire connects) jumpered to GND.

pin 2 - LOW - where white/blue wire connects
pin 3 - MED - grey wire
pin 4 - HIGH - yellow wire

If the fan does not come on when +12V is applied to pin 3, that may help explain seeing 245°F on the display, and also indicate the fan needs replacing.

Doug

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#3 ·
Good morning Doug:
Your reply is much appreciated! I have noted that the cooling fan does not seem to always want to kick to high when the temps are in the 240 range. Something I left out of my original post, was that I changed the water pump thinking there could be an issue there. Once off, the WP seemed mechanically, good, but there did appear to be small leak. When I fired it back up after that, the fan was on high, and did not seem to want to slow down. I shut the car off, and the fan did not restart when I restarted the car.

I'll test the fan as you recommend. The other cars we have don't seem to run quite as warm as this thing.


TIA Don
 
#4 ·
Well:
I ran it again today after topping off the coolant. The fan seemed to run more like I thought it should. It started out on low speed, and then bumped up the speed when the info cluster temp got to 230. I ran it around a while, and the temp would move around between 220-240. I am very unimpressed that the temp gauge stayed right at a needles width below halfway. That is crazy! If one does not have the info center temp up, you will never know about the wild temps swings.

I sure as hell hope this thing does not have a head gasket issue. I don't want to regret adding it to the fleet.

Don
 
#5 ·
Well:
I ran it again today after topping off the coolant. The fan seemed to run more like I thought it should. It started out on low speed, and then bumped up the speed when the info cluster temp got to 230. I ran it around a while, and the temp would move around between 220-240. I am very unimpressed that the temp gauge stayed right at a needles width below halfway. That is crazy! If one does not have the info center temp up, you will never know about the wild temps swings.

I sure as hell hope this thing does not have a head gasket issue. I don't want to regret adding it to the fleet.
Unfortunately, I've not found adequate documentation for how the temp sensor info is processed for the gauge and for the info center display. But considering there are two coolant sensors may help explain why you see such different behavior between the gauge and the display.

Doug

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#9 ·
The gage is computer controlled and as long as the car is running in the 190 to 240 range the needle won't move. The temperatures you're seeing on the digital readout are ok as long as they go down when the engine is under load and up when it's not under load.
 
#10 ·
So, you think the fluctuation we are seeing is not a concern. I am used to a 5 degree swing on most of the cars I have owned, but not 10-20 once it's up to temp. How hot would you say is too warm? I am not real comfortable with 230, let alone seeing 240 or 245. I know the T stat is 221.

Don
 
#11 ·
So, you think the fluctuation we are seeing is not a concern. I am used to a 5 degree swing on most of the cars I have owned, but not 10-20 once it's up to temp. How hot would you say is too warm? I am not real comfortable with 230, let alone seeing 240 or 245. I know the T stat is 221.
Here's the description in Chilton's online manual:

Thermostat controls the flow of coolant and is mounted to the cylinder head. The thermostat contains a wax pellet that expands and contracts based on the coolant temperature, which will mechanically move the main spring and a sealing disc to control the flow of coolant. It is assisted by electric power in order to open the main valve earlier than original opening temperature. The thermostat will begins [sic] to open electrically at 90°C (194°F) under full load condition and will begins to open mechanically at 105°C (221°F) under part load condition. It will be fully opened at 120°C (248°F).

So this does indeed indicate a very wide operating range of more than ±25° about the 221°F center point. Also note the mention of "electric power" - ie, the heating element - to open the thermostat early.

So I don't think the numbers you are seeing merit worrying.

But do keep a close eye on the coolant level. That's the first sign of leaking, which seems to be common on this car. As you're probably aware, the coolant outlet, thermostat housing, and surge tank are known failure points. But, having serviced those on my two LS Cruzes, I am satisfied I've got the upper hand now :)

Doug

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#12 ·
WOW:
Your time an effort here Doug are much appreciated.
What a crapshow of a T stat operating guideline. Some engineer really must have been smoking something when he/she designed this thing. Clearly a case of, "Gee, lets see how complicated we can make such a simple thing."

I am a big fan of the KISS principle, but this is crazy.

The Cruze is for our 17 year old daughter to use. I can handle issues being a car guy, but don't want her to have to worry about them. I think those of us who are parents can identify with that.

Don
 
#13 ·
WOW:
Your time an effort here Doug are much appreciated.
Thanks. That's very nice of you to say.

What a crapshow of a T stat operating guideline. Some engineer really must have been smoking something when he/she designed this thing. Clearly a case of, "Gee, lets see how complicated we can make such a simple thing."
I had similar thoughts when I first saw the fan control schematic. I think my comment was, "This is what happens when mechanical engineers design logic circuits" :)

The Impala fan control is almost as bad, with 3 relays controlling two 2-speed fans.

That said, showing due respect to some guys who have done some amazing engineering, maybe there's graceful failure engineered into that 5-relay concoction that's not readily apparent from the schematic.

That is, if there are only 3 speeds to command, why not just have three relays controlled by three outputs from the ECM instead of two? Surely the added cost of two more relays is much greater than the savings of one ECM output. So there must be some other advantage to having those extra relays such as added reliability or some kind of quasi-redundancy in them.

The Cruze is for our 17 year old daughter to use. I can handle issues being a car guy, but don't want her to have to worry about them. I think those of us who are parents can identify with that.
My 22yo daughter is driving our 2012 Cruze, and so far, so good! She loves that car, and still hasn't hit 100k miles. So I'm hoping for many more miles out of it, knock wood !

Doug

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#14 · (Edited)
Amen to the thought that both of our daughters get many more happy, trouble free motoring miles from their Cruzes.
For the most part, I am a Dodge guy at present. I have a good old trusty but rusty 2004 Durango SLT Hemi for my DD, and a much nicer 2014 Charger R/T AWD for nice weather that spends a lot of time in the garage.

I've had GM, Ford/Mercury, and now Dodge as the years roll by. My wife enjoys a 2011 Hyundai Sante Fe AWD 3.5L for her DD. No real complaints to date about any of them, other than a bit thirsty for fuel here and there. Most of our commutes are short, so it's not a huge issue for us.

Don
 
#15 ·
As a follow up, my wife and I took a nice 25-30 mile drive around the county this afternoon. Ambient temps were in the mid 70's. I ran the AC the entire way, The DIC reported coolant temps running between 220 and 235 for most of the trip. At one point while in a drive through, DIC temp hit 240, and the radiator fan went to ludicrous speed for minute, bringing the temp back to 230. At no time did the ominous "AC off, engine too hot" DIC message rear it's ugly head.
I have to wonder if the cooling system is indeed operating as designed? I still cannot wrap my head around a 221 degree thermostat though. Both of my 5.7L Hemis run 203 degree T stats from the factory.

Don
 
#16 ·
Good Tuesday morning:
I find myself a bit frustrated with our daughter's 2012 LS, that has just turned 83K. We have had it a little over a year, and other than the well known plastic T stat assembly leak, it has been problem free. At present, the dash coolant temp gauge says that engine temps are good, but the dash info display is telling quite another story.
The display advises that engine temps are running from 225-245.

I have replaced the radiator temp sensor with no change. The engine temp sensor was changed along with the T stat when the plastic coolant pipe was replaced with the nicer aluminum unit. At times, the A/C would shut down along with the "AC off engine temp too high message." This has not reappeared since the radiator sensor was changed.

The dex cool has been replaced with some good gold colored G0-5 coolant. From what I have read, it can be a PIA to get the air out of this cooling system. I am aware of the bleed screw on the top pass side of the radiator. Any helpful hints for this process would be very much appreciated.


TIA Don
I feel a little stupid for asking this, but...My daughter has a 2013 Eco and I can't find a dash display that reads engine temps. Is it part of the menu of items that is displayed between the tachometer and speedometer? Or is it part of the display in the center dashboard of the car?
 
#17 ·
Svenny:
No dumb questions here. The display I speak of, is the one centered between speedo and tach. You push the rectangular button on the turn signal stalk, and then roll the collar beside it up or down to scroll to the screen you want if I recall correctly.

Don
 
#19 ·
I have it on my 2012. Not sure if it's on my 2013. For sure, while the engine temp is indeed displayed on my 2012 DIC, it's not listed in the owner's manual.

There was a thread here some time ago about this. I have the foggy recollection that the temp display was eliminated.

Doug

Text Diagram Line Parallel


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#21 ·
Update:
Apparently, the "AC off, engine too hot" message monster is not tamed yet! My daughter let me know a bit ago that she got the DIC message while driving around today. I think I am gonna have it evaluated for a bad head gasket. I sure hope not though, at 8ish years old, and 83K.

I have had very good luck on the used cars I have bought through the years. I am hoping this Cruze does not turn out to be the car from hell..............

Don
 
#22 ·
Update:
Apparently, the "AC off, engine too hot" message monster is not tamed yet! My daughter let me know a bit ago that she got the DIC message while driving around today. I think I am gonna have it evaluated for a bad head gasket. I sure hope not though, at 8ish years old, and 83K.
Well, shoot. Sorry to hear it's back.

Did your daughter get a look at the temp gauge when this happened?

Doug

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#23 ·
Yes Doug:
The smaller temp gauge on these cars is a joke! The car could be ON FIRE, and the little gauge will read a hair below half way. I am thinking and hoping that the new thermostat and it's housing are junk. The piece itself is aluminum, and looks 10 times better than the oem plastic housings that are known to warp, crack, and leak.

If not for the DIC, you would not be able to get a decent temp reading until major problems were underfoot.

Don
 
#24 ·
Yes Doug:

The smaller temp gauge on these cars is a joke! The car could be ON FIRE, and the little gauge will read a hair below half way. I am thinking and hoping that the new thermostat and it's housing are junk. The piece itself is aluminum, and looks 10 times better than the oem plastic housings that are known to warp, crack, and leak.


If not for the DIC, you would not be able to get a decent temp reading until major problems were underfoot.
Hi, Don,

What I was thinking is that often the "AC off, engine too hot" message is accompanied by either a temp gauge needle all the way down on C, or way up close to H.

If it was down on C, that would indicate a sensor issue such as a bad connection or damaged wire (or it would indicate a very low coolant level).

If the warning went away, and the gauge went back to just below half, that would seem to indicate the sensor started working again which is consistent with a bad - intermittent - connection.

That said, I think a bad connection might set a code.

On the other hand, if the gauge was near or up in the red when the warning was displayed, that would indicate an actual over-heating condition. Assuming adequate coolant level and a working water pump, I'm wondering if there's a bad - intermittent - fan relay that failed to get the fan going when it should.

I know the temp gauge is not well liked here, but in the absence of any other temp indicator, that's what we have to work with.

Chasing an intermittent relay is a pain never mind the risk of over-heating waiting for one to not connect. I hate shot gunning parts, but maybe replacing the high speed fan relay is worth doing.

Another thought is to leave the code scanner hooked up monitoring the engine temp so that data can be collected when another warning message occurs. That's an extra burden on the driver, but it might provide some correlation with the warning message.

HTH.
Doug

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#25 ·
Doug:
Again, your comments are appreciated. The temp gauge thus far has yet to move above the normal position of a needles width below half way. As far as the warmup sequence goes, it does that part just fine.

As far as the fan goes, it seems to do it's thing when needed. I had a nice drive this evening in my '14 R/T Charger. The DIC indicates 199-205 as a normal operating range. It's T stat is 203 degrees. Still cannot wrap my head around a modern engine running normally in 220-235 degree temps. I'll keep after it one way or another.

Don
 
#26 ·
I'm fighting coolant leaks right now, but have been looking around at cooling system topics in this forum quite a bit. After I fix the current turbo coolant return line leak, I am planning to change the thermostat as described here:


With all of the plastic parts in this coolant system, I think it's better to run cooler.

This probably isn't your problem if yours is getting hotter than it should, but just thought I'd share.
 
#28 ·
I have to wonder if GM then gave us what they felt was a more important parameter in place of engine temp? Being old schoo, l I know that coolant and oil are the lifebloods of an engine. I would hope that they improved the "U" in useless dash temp gauge when they did this. It used to be, if you had an idiot light, you hoped that it "might" come on before the damage was done. In the case of a gauge though, you could monitor the beginning of the issue as the problem progressed. Now it seems, they have turned some of the gauges into nothing more than a facade...............

SMH Don
 
#29 ·
Trust me. Better the gauge not move then move. Battery voltage is a classic example

“My battery keeps running down to 13V!!! WTF IT SHOULD BE 14V THE CAR HAS NEVER DONE THIS BEFORE”. It’s working as intended.

or....

“My engine speed keeps wiggling!!!” Yes even the tachometer is faked and smooth.

or of course...

“When I accelerate the coolant temp goes up. Why Chevy why?!?”


That’s why.
 
#30 ·
Snipesy:
I would agree with you that having the gauges be too sensitive would also be problematic. Beyond that, not having any change in reading, especially when the situation at that time could be very damaging and costly is no good.

One of those cases where what the driver does not know can be very costly.

Don
 
#31 ·
Another update, and hopefully the final one. I got the Cruze back to the local folks who performed the original repair (March of this year) when the oem plastic coolant housing was leaking. As I thought, the "new" thermostat housing (Dorman 902-033) which is electronically as well as mechanically operated was not working correctly. They said it was not allowing proper coolant flow until 240 vs 215 which is the spec. Thankfully, today's work was done under their 12/12 warranty, so no charge.

Don
 
#32 ·
Just wanted to confirm that it appears that the "new" Dorman T stat/housing assembly was indeed the culprit. Since the 2nd one was installed almost a month ago, no more overheating, and no more "AC off, engine too hot" DIC messages. While I am at it, should any of you be in the area of SW Ohio, University Motors in Oxford is a good place to have automotive work done. Like everyone, they are not perfect, but from what I have seen, do an excellent job of standing behind their diagnosis and repair.

YMMV

Don
 
#33 ·
As an additional follow up, when I had the valve cover replaced back in December '21, University Motors concluded that the Dorman T stat/housing had a fail(ing) sensor. It was replaced a 3rd time under the lifetime warranty. It's really a shame that this part is so problematic. The all aluminum construction is 10x better than the plastic of the oem unit. It seems though, that the sensors on the Dorman unit are problematic.

Don
 
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