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Discussion Starter #1 (Edited)
OK, let’s start!
I had multiple Cruze cars since 2011, unfortunately I can’t say I have/had one free of issues! Talking about the heating and cooling, I saw different & multiple issues reported by people. I did many changes to my cars during the years and I’m going to share with you a few interesting things about the thermostat, specific for 1.4L turbo (ECO). It can be similar issues for other trims, even for Diesel, but the cars I tested & modified are Cruze ECO 2011-2012.
Based on testing 4 cars, here are my observations:
First, the “input data”:

  1. The OE Thermostat on Chevy Cruze ECO (1.4L turbo) from 2011 to 2016, is with a wax thermostatic element that starts opening at 105°C (221°F).
  2. The OE Thermostat is also wired and controlled by ECM. Based on different algorithms and program codes, the thermostat can open at any temperature at any time, if the ECM requires that!
  3. The water temperature display gauge is… a joke! I monitored it for different cars and compared with data from OBD. The dial moves when the temperatures increases until… until 185°F (85°C) only! Then stays there, right before 6 o’clock, no matter how high is the real water temperature. When I tested this, I changed the coolant concentration, adding much more water into the system and let the engine run until the water started boiling. The gauge was at the same position max position, telling me “everything’s ok!
Gauge.jpg

4. The expansion OE tank cap is opening only at 20PSI.

Under all these conditions, the coolant temperatures during normal driving conditions stays around 220°-230°F. I said normal driving conditions because when the engine is overheating, the ECM controls and changes everything. It may open the shutter grille to help cooling down and also it can open the thermostat at any temperatures it “wants”, based on data collection. So, not only that you drive with coolant at high temperature, but also the entire system is at high pressure, since the tank cap opens over 20 PSI. In theory, a higher engine operating temperature helps improving its performances. Well, maintaining a higher temperature for the engine and cooling system requires also better quality system parts. Coolant’s boiling point is way too high under the condition I mentioned so everything is ok until… One small crack into the system will lower the PSI and of course the boiling point of your coolant. Add adding more water into the system and you will lower it even more until the coolant will start boiling time to time, without you notice it I replaced the recovery tank a few times, and many hoses all the time! Many others did the same things on this forum.
Sick of changing parts all year along I decided to change the thermostat and go “old school”. It took me a while until I found something that works but here is what I did. I bought a new thermostat housing 55593035Dorman 902-2080 (GM) that is for Cadillac ELR 2014 Chevy Volt 2011-2014. Do not buy MotoRad, it is a different new model, it will not work! You need the one with the “cage”, see the attachment. The housing is different from the outside, but the internal thermostat is fully compatible with Cruze’s thermostat housing. Push the cage and rotate as in my picture, then take out the spring and “cage”. The thermostat will come out relatively easy. It looks the same as the other one, only the wax inside is different and starts opening at 176°F (80°C). Be careful with the 2 legs, don’t bend them so they can go straight back into the housing.
I’ll not got into details of how to take out the existing thermostat, there are good posts on this forum. Put everything back, and make sure you have enough coolant. Then, old school again, I changed the tank cover with one that is opening at 15 PSI, not 20 PSI (MOTORAD T46 )!
I did this replacement on 6 ECO-s and these cars have between 500 to 3200 miles since. No issues at all! The temperature goes usually up to ~184°F then the thermostat is fully opened so the temperature goes down around 180°F. I didn’t notice any drastic changes to MPG! I have hot air blowing inside the car as I had before the swap.
I did all the changes I mentioned because me and my friends have multiple issues with the cooling system since 2011. If you like the solution and have questions, please let me know. I don’t want to argue with anybody about why GM built the system in the way it is so don’t challenge me! :p

T00.JPG OLD.jpg NEW.jpg
 

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So you put the "Guts" of the new Dorman thermostat in the original Cruze housing?

Both the Cruze and the Volt share the same 1.4L engine. The Volt not having the turbo. Are the gaskets and mount holes not the same between the two thermostats?

Why couldn't you just use the Dorman thermostat as is?

I agree that as these cars get older leaks are going to be bigger issues.
 

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I think you should have spent more time identifying the root cause of your other problems. In my ownership of the Cruze I haven't had to replace those components and haven't had to top off any antifreeze.

I don't think what you did was a good idea. The engine needs to run hot enough for efficiency and without a re-tune, you might see a drop in fuel economy. Furthermore, engine oil needs to operate above the boiling point of water to prevent condensation and water contamination from building up. That point is 212F. You running the thermostat below that temperature means you'll likely also need to change oil more often since oil will not reach above the boiling point of water, which may cause it to break down more quickly.

A 195F thermostat may have been more appropriate.
 

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That's why the day my water pump broke, the engine's fan was going full throttle, while the temp gauge stayed in the center, not moving an inch.
The engine was basically running dry on coolant. I could swear it would be coitus-ing up my car!
 

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I can confirm using my ultra-gauge that the temp gauge is completely useless, and as OP mentioned, it reaches one tick below half at 185F and does not move from 185-226. The car during initial warm up will reach as high as 226.4F before opening the thermostat and settling back down between 208F and 221F. If I remember correctly, there are only two other places the temp gauge will touch over the "one tick below half normal operating point" It will go to 3/4 when the computer senses an overheating condition. This will also trigger the A/C Off due to high temp alarm on the DIC. The other is it will reach 100% hot when the computer senses a severe catastrophic failure such as a "no coolant" condition.

I also agree messing with the thermostat operations as designed may have unintended negative consequences, and I can't recommend that anyone else on here follows this advice, though I find it very interesting.
 

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My 12 LT has the original Trifecta select-a-tune. With the tune the digital temp, not the gauge reads 199-203 coolant temps. It remains the same in both eco mode and sport mode. Been 80k miles plus and no ill effect with mine.
 

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I don't think what you did was a good idea. The engine needs to run hot enough for efficiency and without a re-tune, you might see a drop in fuel economy. Furthermore, engine oil needs to operate above the boiling point of water to prevent condensation and water contamination from building up. That point is 212F. You running the thermostat below that temperature means you'll likely also need to change oil more often since oil will not reach above the boiling point of water, which may cause it to break down more quickly.

A 195F thermostat may have been more appropriate.
This is interesting. My daughter has a 2015 1.6T and the engine runs around 105C. I have a 2012 diesel and it runs around 80-85C summer or winter. Both our cars have the digital temperature displays and the diesel gauge starts to move at 50C, not sure about the daughter's car as I don't drive it much. The heater starts working before the gauge starts moving.
 

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This is interesting. My daughter has a 2015 1.6T and the engine runs around 105C. I have a 2012 diesel and it runs around 80-85C summer or winter. Both our cars have the digital temperature displays and the diesel gauge starts to move at 50C, not sure about the daughter's car as I don't drive it much. The heater starts working before the gauge starts moving.
Diesels are a bit different.

In colder climates, we routinely see people freaking out over finding a white residue on their oil cap, thinking they have a blown head gasket. Turns out it's nothing more than condensation from short trips that don't allow the engine to reach operating temperature. The solution is to go for a longer drive to fully warm up the engine and vaporize that condensation. That becomes quite a problem if you can't get the engine up to a high enough temperature though.

Condensation causes corrosion. Furthermore, condensation mixed with oil causes acidity which depletes the detergent package and drops the base number of the oil. Diesels are not as sensitive to this as the byproducts of combustion are not as acidic. When you have a gasoline engine though, adding more acidity to an already acidic combustion byproduct depletes the additives in the oil in short order.

Even slightly below boiling point, oils manage to release vapors since some areas of the engine operate significantly above coolant temp, but that is a limited range. For example, if your water coolant temp is 220F, you can probably assume your cylinder head is operating at about 235-240F since thermal transfer isn't 100% efficient. However, if your coolant temp is 176F, your cylinder head probably isn't operating at above 200F which becomes a problem over time.

There's just no benefit whatsoever to running the system that cold.
 

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Discussion Starter #9
So you put the "Guts" of the new Dorman thermostat in the original Cruze housing?

Both the Cruze and the Volt share the same 1.4L engine. The Volt not having the turbo. Are the gaskets and mount holes not the same between the two thermostats?

Why couldn't you just use the Dorman thermostat as is?

I agree that as these cars get older leaks are going to be bigger issues.
The housing and seal has a different outside shape, otherwise I would just replace the entire unit. :)
 

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Discussion Starter #10
I think you should have spent more time identifying the root cause of your other problems. In my ownership of the Cruze I haven't had to replace those components and haven't had to top off any antifreeze.

I don't think what you did was a good idea. The engine needs to run hot enough for efficiency and without a re-tune, you might see a drop in fuel economy. Furthermore, engine oil needs to operate above the boiling point of water to prevent condensation and water contamination from building up. That point is 212F. You running the thermostat below that temperature means you'll likely also need to change oil more often since oil will not reach above the boiling point of water, which may cause it to break down more quickly.

A 195F thermostat may have been more appropriate.
Andrei, I now my decision is debatable :) I can argue with you ant tell you that "other cars" are operating using this, or similar thermostat, for years without any issue. Talking about MPG, like I said, I didn't see any major difference yet, nor my friends. I may observe a change in the summer of for long trips. My idea was also to put a thermostat that opens at 195F as you said but I couldn't find any that fits! The existing thermostat is not just opening by temperature but also the ECM can "dictate" when to open, depending of the information it receives from other sensors. If you, or others, could find a thermostat that fits and opens around 195F, please let me know I would use that instead.. Until then, I'll keep monitoring the cars I changes and let you know if there is any major change during the next months.
 

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Discussion Starter #11
Conclusion!

Let me share with you the observations after I did this Thermostat Swap to 4 cars, all have at least 5K since the change:

  • During cold weather the coolant stays most of the time around 184F ±2F. Some exceptions if you are stuck in traffic when the coolant’s temperature goes higher since the “smart” ECM won’t start the fan so early.
  • When is hot outside, over 100F, the thermostat works great, your coolant stays again around 184F most of the time! It is even better than in the cold weather because this time you are using AC and the radiator’s fan works very often, getting down the temperature. No issue if you are stuck in traffic, I never got the temperature over 190-192F and that only for a few seconds!
All 4 cars I changed behaved in similar way, I only had same issue with one in particular, until I did a better air flush to the coolant.
To summarize: I got the engine working temperature down from 221++F to ~184F, in order to avoid continuous overheating issue (the gauge is useless, it goes max to 185F, so you can boil the coolant without even know!). I didn’t see any MPG major fluctuation after the change. I never had issues with car warming up during the cold weather, nor overheating during the hot days and rush hours. I’m not going to argue about better engine performance at higher temperature, but this is not a racing car! :D

Ideally.... ideally I'll do the swap to a thermostat that would open at 195F-200F but the only one that fits and I could find is the one I mentioned into the original post. I didn't want to change the housing, add adapters, etc. If somebody can find a better thermostat, let us know! :)
 

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A friend had a Mini (original1966) and had 2 temperature gauges fitted. One for water and the other for oil. The water ran at 180F and the oil went to 250F, even though he had an oil cooler. I know the diff and transmission are in the sump, but the oil still runs hotter than the coolant in most cars that I have owned.
 

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I am really like the idea of a lower temp thermastat. I've always worried more about overheating than condensation in the oil. My old 86' pickup got a 160° F thermastat in it. Now I understand that theses engines are better off closer to 220° and that's fine...givin that the gauge would show it! As y'all have said the gauge goes to a tick below halfway and stops. That is the reason I had to put another engine in my 2011. The fan resistor, on the fan shroud, burn up or messed up from corrosion , causing the fan to only run on "turbo" mode when the a/c high side got to high. Before the engine swap I replaced the head gasket, thinking that was my problem, and when I got it back together I used my ODBll scan tool to monitor the temperature, which goes off the outgoing sensor on the rear of the engine, and saw temps up to 250°f , no fan and the temp gauge on the dash still never got above the tick below halfway. That tells me whoever had the car before me along with myself had been running it hot for a long time and never knew it and cooked the engine. Having an old school thermastat at a slightly lower opening temp would make me feel a lot better.
 

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1st, thank you CRUISE-CRUZE for the research and time it took to find the parts to do this!
i have done this and am VERY happy with the results. my car is now running at 185° ± 5°. Most of the time i run 180° but when climbing a steep grade on my daily commute the temp does raise to 190°. i have noticed if i let the car sit and idle for an extended period of time (30-40 minutes) the temp will climb to 210°.
the last few weeks the temp has been in the high 20s to low 30s F i have had no problem with the heat in the vehicle.
After my commute to work, the coolant temp is always about 180° and i have taken several temp reading of the cams and the temp of the cams was 218°F. i do not have a way to measure the oil temp but an infrared thermometer aimed at the cams under the oil fill cap is good enough for me. this temp of the cams mitigates the thought that the oil will not get hot enough to evaporate moisture.
my MPG has not changed at all

i ordered the following from rockauto

MOTORAD T46 - CAP
DORMAN 9022080 - Thermostat
DORMAN 603383 - Coolant recovery tank

why isnt this a sticky?
 

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Discussion Starter #15
1st, thank you CRUISE-CRUZE for the research and time it took to find the parts to do this!
i have done this and am VERY happy with the results. my car is now running at 185° ± 5°. Most of the time i run 180° but when climbing a steep grade on my daily commute the temp does raise to 190°. i have noticed if i let the car sit and idle for an extended period of time (30-40 minutes) the temp will climb to 210°.
the last few weeks the temp has been in the high 20s to low 30s F i have had no problem with the heat in the vehicle.
After my commute to work, the coolant temp is always about 180° and i have taken several temp reading of the cams and the temp of the cams was 218°F. i do not have a way to measure the oil temp but an infrared thermometer aimed at the cams under the oil fill cap is good enough for me. this temp of the cams mitigates the thought that the oil will not get hot enough to evaporate moisture.
my MPG has not changed at all

i ordered the following from rockauto

MOTORAD T46 - CAP
DORMAN 9022080 - Thermostat
DORMAN 603383 - Coolant recovery tank

why isnt this a sticky?
Thank you for your post! A few other people asked me and it is good to know when somebody else does changes that are working and help us to deal with our issues. I counted 9 cars, including you, that I'm aware about this change (or I did it myself to a few) and have no more issues. Two main things to watch:

1. The thermostat has 2 version, one version you can't take out the inside component so you need the other one, see it also here:
https://www.ebay.com/itm/112394548622?ViewItem=&item=112394548622&ppid=PPX0

2. Make sure you properly add back the coolant after the replacement and take out the air from the installation when done!

As a remark, the latest Cruze model (1.4 turbo) is using the OE thermostat that opens at 82 Celsius! You can't use that model, it doesn't match to our 2011 & 2012 models but just for your reference only, the thermostat that opens at 105C "to improve car performances" is for a different application, market, in my opinion. :D
 

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Let me share with you the observations after I did this Thermostat Swap to 4 cars, all have at least 5K since the change:

  • During cold weather the coolant stays most of the time around 184F ±2F. Some exceptions if you are stuck in traffic when the coolant’s temperature goes higher since the “smart” ECM won’t start the fan so early.
  • When is hot outside, over 100F, the thermostat works great, your coolant stays again around 184F most of the time! It is even better than in the cold weather because this time you are using AC and the radiator’s fan works very often, getting down the temperature. No issue if you are stuck in traffic, I never got the temperature over 190-192F and that only for a few seconds!
All 4 cars I changed behaved in similar way, I only had same issue with one in particular, until I did a better air flush to the coolant.
To summarize: I got the engine working temperature down from 221++F to ~184F, in order to avoid continuous overheating issue (the gauge is useless, it goes max to 185F, so you can boil the coolant without even know!). I didn’t see any MPG major fluctuation after the change. I never had issues with car warming up during the cold weather, nor overheating during the hot days and rush hours. I’m not going to argue about better engine performance at higher temperature, but this is not a racing car! :D

Ideally.... ideally I'll do the swap to a thermostat that would open at 195F-200F but the only one that fits and I could find is the one I mentioned into the original post. I didn't want to change the housing, add adapters, etc. If somebody can find a better thermostat, let us know! :)
Question: What impact has running cooler had on your emissions? Part of the reason the Cruze runs so hot is for emissions purposes - hotter engines tend to burn cleaner.
 

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Discussion Starter #17 (Edited)
Question: What impact has running cooler had on your emissions? Part of the reason the Cruze runs so hot is for emissions purposes - hotter engines tend to burn cleaner.
First, the facts:
1. GM is using the same thermostat on an actual engine (Volt)
2. GM changed the thermostat to the 2019 1.4L turbo to a mechanical one that opens at 82C!
3. The gauge doesn't go over 185F (85C), telling you that "everything is ok" although many people boiled their coolant without even knowing it!

You are too aware of emissions! :)
The higher coolant temp and higher pressure is also for higher performances, on theory. Since the Cruze is for "general population" the extra cost didn't worth it! Extra "saving" features as the smart grille that shouts down under certain conditions (I monitored that for long time) were obsolete nowadays since the initial advertising worked but otherwise the 0.5 MPG gain is worthless!

"Electronically controlled thermostat: The coolant thermostat’s operating point is electronically controlled to optimize engine temperatures during different phases of operation to enhance fuel efficiency. The engine control module monitors sensors and controls the thermostat based on mapping that takes into account the wide range of engine operating conditions, including temperature and load." Sounds awesome but in reality it causes more issues than advantages so GM changed to a mechanical thermostat for the 2019 models, even before!



To summarize it: today GM is using a similar thermostat for 1.4L turbo as I used to replace the original one. No sensor on my car or my modified cars came on (or check engine) to tell me that something doesn't work properly. So... it is your own choice to do the swap or not based on all these information ... :)
 

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The summer here it gets into the high 90s to low 100s. I have always put lower temp thermostats in my vehicles for this reason. Thanks to Cruise Cruze I can now run a cooler thermostat in my Cruze too

Doing this isn't for everyone. Either is the big brake mod or the PCV mod or the CDV mod.

This information is valuable to those who would like to do this

Sticky this



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First, the facts:
1. GM is using the same thermostat on an actual engine (Volt)
2. GM changed the thermostat to the 2019 1.4L turbo to a mechanical one that opens at 82C!
3. The gauge doesn't go over 185F (85C), telling you that "everything is ok" although many people boiled their coolant without even knowing it!

You are too aware of emissions! :)
The higher coolant temp and higher pressure is also for higher performances, on theory. Since the Cruze is for "general population" the extra cost didn't worth it! Extra "saving" features as the smart grille that shouts down under certain conditions (I monitored that for long time) were obsolete nowadays since the initial advertising worked but otherwise the 0.5 MPG gain is worthless!

"Electronically controlled thermostat: The coolant thermostat’s operating point is electronically controlled to optimize engine temperatures during different phases of operation to enhance fuel efficiency. The engine control module monitors sensors and controls the thermostat based on mapping that takes into account the wide range of engine operating conditions, including temperature and load." Sounds awesome but in reality it causes more issues than advantages so GM changed to a mechanical thermostat for the 2019 models, even before!



To summarize it: today GM is using a similar thermostat for 1.4L turbo as I used to replace the original one. No sensor on my car or my modified cars came on (or check engine) to tell me that something doesn't work properly. So... it is your own choice to do the swap or not based on all these information ... :)
The 1.4T engine in the 2nd generation Cruze isn't the same engine as the one in your Cruze. While the Volt's 1.4 engine in the Gen 1 Volt is the same base engine, it never runs as hard as the one in the Cruze does and in fact never exceeds 4500 RPM. The engine tuning in the two cars is dramatically different.

As for being aware of emissions, you would be aware of them as well if you drove under an electronic highway sign every day and over half the days of the year it's urging you to not drive because of air quality problems. Although no CEL came on when you swapped to a lower temperature your car isn't burning as clean.
 

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The 1.4T engine in the 2nd generation Cruze isn't the same engine as the one in your Cruze. While the Volt's 1.4 engine in the Gen 1 Volt is the same base engine, it never runs as hard as the one in the Cruze does and in fact never exceeds 4500 RPM. The engine tuning in the two cars is dramatically different.

As for being aware of emissions, you would be aware of them as well if you drove under an electronic highway sign every day and over half the days of the year it's urging you to not drive because of air quality problems. Although no CEL came on when you swapped to a lower temperature your car isn't burning as clean.
cars with a tune aren't running as clean. cars with dirty air filters arent running as clean. cars with old plugs arent running as clean.

AGAIN

This isn't for everyone. This needs to be a sticky for those wanting to do this

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