Installing a colder thermostat might set a DTC for thermostat performance sooner or later. The ECU monitors operation of the thermostat by comparing engine and radiator Temperature and maybe also ambient temperature and expects specific values after a certain engine run time. If they`re not met, it will set a code and MIL after a few drive cycles
You can alter the desired ECT by changing it in the calibration

@BigLee:
the engine does have internal exhaust gas recirculation.. this is realized by the VVT system, not by an external EGR valve.. in medium load conditions, specific timing of the exhaust cam makes the exhaust valves stay open for some time of the intake cycle… this allows some exhaust gases to be sucked back from the exhaust manifold into the combustion chamber and being burned again. In this engine this is enough to reach the desired emissions

 

Well, my car has been through a few hundred drive cycles with the cooler thermostat, and so far no codes.
Not saying it wont ever set a code for low temp. Fall and winter are approaching, and we'll see how things go then at ~176°
It went through last winter at ~190° without issues.

And VVT isnt there to provide EGR.
The valve timing alterations needed to attain sufficient exhaust gas dilution would almost certainly be detrimental to both fuel economy and driveability. While it's true that you almost always have some residual exhaust gas in the cylinder from the previous firing, it's not enough to to prevent NOx formation threshold.
The formation of NOx is actually an indication of a more fuel efficient combustion event, as it provides more heat (and thus pressure) to drive the piston with.
The converters break down the resulting NOx...

 

Valve overlap. I think that's what it was called.

Engines have always had that.

Intake opens up slightly before TDC. Exhaust closes slightly after TDC.

Probably different these days. As far as timing to piston position.

 

Sorry, VVT on a gasoline engine can be used for internal EGR and top optimize torque and power ..

check this for example

Exhaust Gas Recirculation (EGR) System

 

Key words are "can be used".
Like I said, if you are using VVT as EGR, then you are sacrificing power, drivability and fuel economy for NOx reduction.
What a waste of VVTs potential, when either an actual EGR valve or converter could be used to achieve it, while letting VVT focus on it's more beneficial aspects.
Besides, many non-VVT engines have also ditched their EGR valves as well.
The later model Chevy 4.3s (iron) and LS family V8s (pre-VVT models) come to mind.
So how are they controlling NOx?
The converters...
Converters are the preferred method of controlling NOx now.
It let's VVT focus on more beneficial things, and eliminates the efficiency reducing aspects of diluting the intake charge with buffer gas, which requires increased ignition advance to maintain efficiency, reduces peak heat energy extraction, and increases the odds of misfires.
All three of these things are undesirable.

Causes of High NOx Emissions

NOx (or nitrogen oxide) is a chemical in automotive exhaust that gets created when the temperature inside a vehicle engine's combustion chamber exceeds 2,500 degrees Fahrenheit. It is a pollutant that helps create smog, acid rain and particulate pollution. This can cause health problems for...

itstillruns.com

Technology Details | MECA

www.meca.org

 

Sorry.
Double post.

 

NOx increases as engine temps increase. As already posted.

That's why I"m surprised GM went with a 220 thermostat for the gen1. More NOx is produced.

Could also be why imports run 180. Less NOx.

And that. Is what's taught in emissions classes. Or was.

When I took it. It was mostly centered around Cali's smog problem.

 

NOx increases as engine temps increase. As already posted.

That's why I"m surprised GM went with a 220 thermostat for the gen1. More NOx is produced.

Could also be why imports run 180. Less NOx.

And that. Is what's taught in emissions classes. Or was.

When I took it. It was mostly centered around Cali's smog problem.

Apparently GM felt that hydrocarbon emissions were a bigger issue than
NOx was.
For what little increase you get in NOx from a 30-40 degree increase in coolant temps, I guess they figured that improved catalyst designs were up to the job of handling it...

As for import brands staying with cooler thermostats, maybe they figured the pros didnt outweigh the cons.
It would seem that with the Gen2 1.4s, that GM has finally come to the same conclusion that the imports did.
If GM had reached that same conclusion on the Gen1 engines, it probably would have saved them MANY millions of dollars in warranty claims over the past several years, AND give them a more satisfied and loyal customer base as well...

 

currently we have a big NOx and particle discussion in Europe.... on Diesel engines EGR is mainly used to reduce NOx… high EGR rates reduce NOx but increase soot particle emissions… so this has to be balanced… as converters do not fully convert NOx, they add DEF fluid to chemically reduce NOx.. on gasoline engines EGR is used to reduce fuel consumption in low and medium load conditions..EGR generally reduces combustion temperatures. On gasoline engines it is possible to do Internal EGR with the VVT system. Reduced combustion chamber temperatures also mean less tendency to knock. Downside of EGR can be driveability issues and oil contamination. Reducing emissions of the raw exhaust is always preferred over using expensive components for aftertreatment

 

Diesel and gasoline approaches to handling emissions are rather different. With similarities but almost apples and oranges in the end.

 

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!

View attachment 254945

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!

View attachment 254953 View attachment 254961 View attachment 254969

Did your modulations fix the issue with your coolant behind expelled through the overflow and then subsequently overheating.

 

Yes, none of the cars I fixed had any issues with the coolant after the swap. Didn't see any changes to the MPG also.

 

Since the weather has been getting cooler, I have noticed that the coolant temps have risen by about 3-6 deg. F
It's especially noticeable in the mornings when the heater is in use, less so in the late afternoon when temps are warmer, and the heater isnt needed.
Here's what's i believe is happening:
Now remember, the 1.4s thermostat is on the INLET side of the engine, while the coolant temperature sensor is on the outlet side.

As such, its opening point is influenced some by return side coolant from the radiator temperature, and by the recirculation coolant from the heater core that's used to provide engine heated coolant across the thermostat's wax pellet.
Now in warm weather, the heater isnt used, so it doesnt loose any heat to interior airflow. In cooler weather, the heater core is used, and the coolant temp is reduced as it exits the heater, and returns to the thermostat housing. This cooler "sampling" coolant in turn postpones the thermostat's opening by several degrees, which in turn causes a slightly warmer coolant operating temp in cool weather.

So for these engines, this is a normal occurrence...

 

Update: since doing this mod about 4 mos and 4000 miles ago, i have had zero problems. Its now winter and i was curious as to whether the heater would be able to provide as much heat as before. Yeah. It does.

 

I have a 2012 diesel ans a few days ago the outside temperature was over 40C and the engine was at 78C. Today it was a pleasant 23C and the engine was at 82C. The a/c is set at 23C, so no heater was involved, so my guess is that as the diesel (in Australia anyway) has 2 fans it must simply supply more cooling in hot weather. I suspect one of the fans runs constantly when the a/c is on. My daughter's 1.6T which runs at 105C has just had a new thermostat at 90,000km.

 

Why not use a 95 C thermostat , on this
parcayedek.com/gates/31368-termostat-10-astraj-corsae-14-a14net-gates-1620318.html

 

That works out to about 203°F.
Still warmer than I care for.
But that part # doesnt seem to be available in the U.S.

 

I use it 203 °F.
how much do you want it to work,
considering fuel saving and heat ? 197 ?

 

I'm not sure what you are asking here.
But 176-183°F seems to be working great for me.
Fuel economy is better than ever, and my heater will end up running you out of the car if left at max...

 

I agree, I have digital temperature in my DIC and the round gauge starts to work at 51C, but even before that I am getting reasonable heat into the car. While 2-6C may not seem cold for winter it is cold enough to need a heater. I have automatic a/c and leaving it at 23C all year round works fine even at 40+C. By the way the Australian diesel Cruze doesn't have an electric heater and the engine runs at about 80C but takes a long time to get there in winter.

 

Is it correct to work open at 190 ° F in summer and 203 ° F in winter?
Does it matter whether it's summer or winter (190 ° F)

when the engine temperature is more than 194°F degrees
cooling fan works when the car stops.
fan stops when car moves.
Could the replacement of the thermostat break the fan?

 

Could the replacement of the thermostat break the fan?

No.

 

Before you decide to perform this modification, read this: measure 1.4 thermostat resistance question, P0599

 

Before you decide to perform this modification, read this: measure 1.4 thermostat resistance question, P0599

Heat and pressure are the enemy in a cooling system with many plastic components. The thermostat is a point of failure in the 1.6T engines. There is now available a metal housing for this engine which has proved to be more reliable. Perhaps this is available for the 1.4T as well?

 

So how come my Cruze never gets above 204 ECT? Can a tune change this?

 

The oil temperature is not really related to the coolant temperature and usually runs hotter than the coolant. If this wasn't the case why do performance cars run separate oil coolers? A friend had an original mini minor and fitted a gauge that had a switch that went from the coolant to oil temperature at the flick of a switch, so the same gauge was used for both. Coolant ran at 170F when cruising and the oil ran at 250F when cruising. I know the transmission was in the sump, but it was also ribbed alloy to help with cooling.

 

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!

View attachment 254945

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!

View attachment 254953 View attachment 254961 View attachment 254969

First of all, thank you for this post. I have been racking my brain trying to figure out what to do about finding a thermostat with a lower temperature setting for opening. I have 2014 1.4L Eco with turbo. Will the thermostat tou mentioned work on this model as well? Again, thank you!

 

All 1.4l turbo Gen1.

 

KENSTV123 is wrong with the thermostat, at least for Gen1. The model needs to have the pins to connect to he wires also, this one is just a thermostat that won't work for Gen1 (1.4l).
Xtrem: in theory yes, you need to find the root cause but in my opinion the quality of components is not the best and you will not be able to keep the high pressure into the system so the coolant will get air and boil. And you are wrong about running the engine at lower temperature, I work withe engines but I won't start arguing, it is a long theory and we will talk forever. I did it for over 20 cars and had only one minor issues in one situation. It works grate in cold (very cold) weather or high temperatures as we had this summer.
To summarize it: who wants to do it can ask me for support but if you want to argue I'll not get involved.

 

Yeah, I realized after I wrote the question that it wouldn't be a full swap, but I was hoping that it would be a candidate for a change of just the guts. $6 is a lot cheaper than $50. It won't be the first thing I work on anyways. I gotta fix a leak on the turbo coolant hose first. I'm trying the cheap "cut the hose crimp off and replace the hose with hose clamps" because removing the turbo isn't on my list of things to do.

 

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!

View attachment 254945

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!

View attachment 254953 View attachment 254961 View attachment 254969

I drilled a 3/16 hole through mine temp stays around 200° +\- 5 you could drill two

 

The only potential issue with that is a slower warm up if you have cold temperatures in your area..

 

today, after procrastinating, I changed over to the lower temp thermostat, and replaced the leaking reservoir with 15 psi cap, and replaced bypass hose that was cracking and the reservoir hose. All parts either leaking or about to leak. milage is 105663. The changeover took about 2 hours, the hardest was removing the small hose from the thermostat....get the right tool, my plyers we’re difficult.
I immediately noticed my temp gauge...it actually fluctuates, looking like all works well.
I will give mpg and overall satisfaction soon

 

r procrastinating, I changed over to the lower temp thermostat, and replaced the leaking reservoir with 15 psi cap, and replaced bypass hose

You will not have any issues just make sure you bleed the air properly from the bleeder valve!

MPG honestly I didn't see any difference, I still got 45MPG average last year for a trip from Detroit to Montreal.

 

Good job there! If you checked my post in detail you will see that the gauge will never go over half way, even if you will boil the coolant! At least for Gen1!