1.4 ECO - Thermostat Swap - 221F to 176F!
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Thread: 1.4 ECO - Thermostat Swap - 221F to 176F!

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    2nd Gear CRUISE-CRUZE's Avatar
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    1.4 ECO - Thermostat Swap - 221F to 176F!

    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 105C (221F).
    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 185F (85C) 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 220-230F. 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 176F (80C). 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 ~184F then the thermostat is fully opened so the temperature goes down around 180F. 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.JPGOLD.jpgNEW.jpg
    Last edited by CRUISE-CRUZE; 02-18-2018 at 08:24 PM.
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  3. #2
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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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    Quote Originally Posted by XtremeRevolution View Post
    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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    Quote Originally Posted by Aussie View Post
    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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    Quote Originally Posted by carbon02 View Post
    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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    Quote Originally Posted by XtremeRevolution View Post
    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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