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Discussion Starter #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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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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Discussion Starter #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
 

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Discussion Starter #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
 

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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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The gauge is just a physically moving representation of the old idiot lights. Cold is the old cold/choke lights, middle is no lights, high is overheating. It's not meant nor designed to convey actual metrics.
 

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More importantly why can’t GM make the **** needle point up. If it does nothing at least make it OCD friendly.
 

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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.
 

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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
 

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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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Discussion Starter #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
 

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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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Discussion Starter #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
 

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Discussion Starter #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
 

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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?
 

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Discussion Starter #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
 

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OK. Hers doesn't give that information. The only operational info there is the voltage, oil life, and tire pressure. Must be different on the Eco. Thanks!
 

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OK. Hers doesn't give that information. The only operational info there is the voltage, oil life, and tire pressure. Must be different on the Eco. Thanks!
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

vehicle_info.jpg


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