[CRUISE-CRUZE]

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.

 

[CRUISE-CRUZE]

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.

 

[CRUISE-CRUZE]

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!

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!

 

[CRUISE-CRUZE]

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.

 

[CRUISE-CRUZE]

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 ...

 

[CRUISE-CRUZE]

..... Although no CEL came on when you swapped to a lower temperature your car isn't burning as clean.

Hehehe! So you don't trust the electronics? How you define then "...as clean"? Let me have bigger concerns than that! Unless... you are driving a full electrical car and have solar panels all around your house and recycle the water you use on daily basis?:th_angelsmiley4:

There are pros and cons but I work in the field and believe me not all the released products on the market are based on proven ideas and detailed tests.
I checked the thermostats for major passenger cars today and tell me if you can find one that is opening over 100C! I couldn't find any! Ideally I would put a thermostat that opens around 90-92C max but couldn't find a direct replacement and didn't want also to change the housing, adapters etc. I'm not going to argue more about "performances & emissions", I just shared my work and the results so others can decide if they want to do or not the swap since the gauge for coolant temperature is useless and you boil the coolant without even knowing it, zero warnings! :wave:

 

[CRUISE-CRUZE]

Question: What would be the effect of just changing the cap to 15lbs? That 25% reduction in system pressure seems where most of the benefit comes from. As far as I can tell, the boiling point would be 267F down from 282F. (This is for generic 50% antifreeze - I couldn't find a table for Dexcool.)

Edit: For Dexcool, it's 260F/266F/277F depending on 40%/50%/70% mixture at 15lbs. I don't know what it is for 20lbs.

What hasn't been addressed is the temperature gauge that doesn't give good warnings. That's going to take a computer solution.

In theory, yes, it is better to have a higher pressure into the system. But in reality the extra pressure damages the hoses, connections, expansion tank, etc. See how many issues are related with that on this forum. Look around to other similar cars and see the cap spec. I monitored long enough the system and the active grille shutter has also influence on controlling the coolant temperature. Not efficient at all under different circumstances, when for example the grille it is locked into a random positions due to the outside temperature. That is another story, they dropped also this extra feature that was very advertised when they came in US with the first Cruze generation. I have mercury tilt switch on the grille connected to an LED inside the car so during the years I could daily monitor its behavior. The thermostat for the first Gen is also "smart" so the computer supposed to properly control the temperature and open/close the thermostat and grille based on different algorithms. The intention was good but not efficient in my opinion....

 

[CRUISE-CRUZE]

Right. I get that. The question is if it's safe to run lower pressure without changing the thermostat. I'm not sure what the peak temperature would be and how much margin is needed.

You just need to keep the coolant from boiling. The boiling point is related to temperature, pressure and % mixture of your coolant (and type of coolant). You can find all these then do the math.

 

[CRUISE-CRUZE]

:tempted:Guys, relax!
I did the change only because I was frustrated like many others to boil the coolant without knowing, I explained also that the gauge temp is useless! I would use a thermostat that would close around 90-95C but there were no options that I could find to replace with minimal changes. And I explained this, even GM change the thermostat later to lower temperature but different housing for the next generation (2017) that opens at... 82C yes! I changed, or help others, to do this change on more than a dozen cars and no issues. I detailed the steps for people who want to improve and avoid issues but don't start arguing now like the Cruze is an F1 car, where every small changes would have a big impact! I keep driving my Cruze/s with this change for that many months, I even forgot about it until I saw this topic opened again. We can debate a lot about it but, unless you have time to put gauges everywhere and go to deep details based on measurements, just look at the real life results: it works! Don't trust it? Don't do it!

 

[CRUISE-CRUZE]

CRUISE-CRUZE, thanks for sharing
this cooler Dorman thermostat.
I have a 13 Sonic, and I have modified a couple of conventional thermostats to fit into the 1.4T housing.
I use a resistor to satisfy the PCMs
Looking for voltage/no voltage on the heater circuit.
This dorman is a much better option though.
It also offers potential to have a driver selectable dual temperature capability.
I wired up a switch to the thermostat heater circuit to manually control it while driving. Once the engine stabilizes at ~178°F, I can turn on the heater circuit, and on the highway, the engine temp will drop as low as 156°F at 85° ambient temp. Takes about 40-60 seconds to drop that much.
This could be good for things such as track outings, ect.
And contrary to popular belief, I believe that cooler operating temps could actually be beneficial to fuel economy.
I think that at lower engine temps, detonation is less common, so more timing advance can be used.

My normal operating temps now run between 173-178°F.
If this seems to be a bit lower than typical, it could be because when I was swapping out the "guts", I noticed that the original spring was about 1/8 inch shorter, and seemed to take a bit less pressure to compress, so I kept the original spring.
Now wether this spring is deliberately calibrated differently, just a manufacturing variance, or has softened a bit from use, I dont know.

Interesting, I like the idea! The only issue is that the temperature gauge is useless (unless they put in Sonic something better?) so you need to watch the temperature to a secondary gauge (OBD) then to act accordingly..
I'm replacing one of my oldest Cruze with a 2014. Same trim: Eco & MT. A lot of downgrades I can see so I'm swapping parts from the old one now. Same issue with the thermostat so I have to swap it again. And it has the PCV issue and the trunk button issue and no light into the glove compartment, etc, etc... I have a lot of re-work to do until fall. I said a few times that owning a Cruze (more) makes me a better mechanic month by month!!

 

[CRUISE-CRUZE]

I agree.
I think that the plastic cooling system components are very close to their limits of durability, especially longterm.
My 13 Sonic has had 4 water pumps (not plastic, but the seals are definitely stressed), 2 resivoirs, a water outlet, and a radiator replaced.
I think that lowering both the temperature and pressure will greatly reduce the stress on these parts.
Lower pressure surge tank caps are available, and are definitely recommended as well.
GM/ACDelco part#s are:
15 psi - 15075117 / RC98
9 psi. - 88986846 / RC108
The 9 psi cap is probably best used after the cooler thermostat, and an auxiliary radiator fan switch is installed.

Just look at my original post and see the picture with the initial coolant reservoir. High temperature & high pressure are not for this vehicle! The 15psi cap works the best, going to 9psi may risk to boil the coolant if the mixture is not properly done.
And I said before, GM moved back to a lower temperature thermostat lately. Look for example the 2018 Cruze, it has the thermostat that starts opening at 180F! In theory, yes, higher temp and pressure will give you better performances. IF.. you use quality components, but if you try to cut cost everywhere, using cheap materials, then have the decency and change also the mechanical components to adjust to the new situation.

 

[CRUISE-CRUZE]

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.

 

[CRUISE-CRUZE]

Did you replace the reservoir too or just the cap?

I did a few swaps like this for multiple Cruze. One in particular I had to replace the reservoir too, it was cracked all over. For others I kept the originals.

 

[CRUISE-CRUZE]

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.

 

[CRUISE-CRUZE]

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.

 

[CRUISE-CRUZE]

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..

 

[CRUISE-CRUZE]

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.

 

[CRUISE-CRUZE]

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!

 

[CRUISE-CRUZE]

See in the pictures what you need to replace. You can push against the spring with your hand but use a glove to protect your fingers.