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Riikanbkk 写了： 2023年 4月 2日 00:08 Ye'are still buzzing nonsense and stupidity. At least go learn some SAE basic mechanical principles and get 60/100 atleast. Don't tell me you dunno what's SAE???

I got perfect score on my SAE engine/tranny drivetrain test so NO thank you I got zero interest your nonsense tuber quotes. Me personally follow only true expert tubers, Ryan/McUncle/BisforBuild/RollaChriz alike. And I am big tech contributor inside yota FB groups, from building to butt-tuning.

It's COMMONSENSE thermostats are not for high-temp regulation, but it is regulating LOW-temperature letting your engine warming up faster( recall SAE: oil pressure is determined by both journal clearance & oil TEMP/viscosity, and remember when you building the engine setting tight measurements, rings gapping, cross-hatching etc. ) and don't cool down too much if you're low load cruising in rainy weather.

What you're sillius confused is thinking thermostat openning temp as limiting high-temperature, which is non-sense, because all cars coolant temp is limited only by cooling capacity & load, and for DAILY CARS they all lacking in cooling cap under heavy load/low speed.

Thermostat openning temp is for don't let colder coolant flow through it, thus warming up faster after cold start. Yeah if your car warming up so fast so hot you could run a aftermarket colder thermostat for lil catching time after cold start, but same flow and cooling capacity, won't get you any meaningful results. Since DAILY CARS lacking cooling cap under heavy load/low speed, even different fans switching temp won't get any difference. Period.

Riikanbkk 写了： 2023年 4月 7日 09:10 Hi if you check my replies in details you know there's usually nothing to worry about...
1) for normie daily cars since water has 20% more heat capacity than gly-mix, usually could just swap. Of course your car going 112C fast is lil abnormal should source that before hand, but summer 112C 50mix is only ~105C at most when running PURE water.

2) cooling system caps are pressured for a reason the usual 0.9-1bar caps will raise boiling temperature by 20C. Bubble shocking hammering could be VERY dangerous -- that's why I said for perfectionist make sure 100% bled off air and maybe increase pressure. BUT then for daily grocerie getters: since PURE water will lower the max temperature, and you're UNLIKELY get to 120C suppose everything sorted out, I fail to see that's a big prob... And since you're experienced in car maintenance you should know how to maintain cooling system properly I suppose

3) I run all my cheapo cars PURE water only -- whether daily getter stocko plumbing, or track day / drag meeting with diy TIG plumbing floor it smashing that Lambo etc. lol. For many years. And inside all jacket and plumbing looks pretty more than acceptable. Convince me.

Of course I live in tropical weather. Being pauper I also always running purified drinking water only. If you run distilled water with proper treatment I mentioned even better, I suppose there wouldn't be any issue( if abnormal heating sorted out ).

4) as I said cooling system caps are pressured for a reason, the usual 0.9-1bar caps will raise boiling temperature by 20C. For all my DIY handmade plumbing all have swirl pots( extract & make sure only air in the entire system are at highest expansion pot ) and 1.3bar higher pressure cap. Not only that gives more 10C space 130C boiling for safety and faster cooling( when hotter ), but also totally removed needs for reservoir as entire cooling system rarely go beyond 1.3bar and no leaking to reservoir. No ganrantee but I found 1.1bar caps are generally OK for normie stocko plumbing if everything proper, would give 5C more space before 125C boiling

5) from my experience thermostats are purely mechanical and reliable usually lasts, unless abandonned junkyards it rarely go stuck. No experience on elec thermostat but as the elec motor serves as fine control on top mechanical function, should be similar reliable perhaps? Than I'll seek diagonizing other issue first step, like run the car heavy pedal but don't use AC or full heater, if big difference I know it's AV plumbing or fans' problem, or engine AFR not abnormally lean then deffo the prob, or pressure wash radiator see if any stuck, etc etc... or sorta like those.

wolf_north_1234 写了： 2023年 4月 7日 16:14 Hi.

thanks for the detailed suggestions.

I checked my car again with scanner, unfortunately the cooling system (thermostat, cooling fan) is controlled by ECU, the thermostate is controlled by ECU as well. I do not have the details on how the thermo is controlled, only below:

at zero volt, the thermo starts to open at 221F (105C)

at 12V, the thermo starts to open at 176F (80C)

No voltage mentioned, the thermo is fully opened at 288F(120C) !!!

the expansion tank cap is a 20 PSI one, in other words, the cooling system max pressure is 20 PSI.

I guess that the voltage is also the ECU function of throttle, gear ration and engine load. I do not have the details on the ECU program.

Anyway, it is much more involved than I first thought. I think the best things I could do are:

1. flush out the whole coolant, flush 3-4 times with distill water, then use the new coolant, make it 50/50.
2. when driving in the condition on high engine load, like uphill, very hot ambient temperature, local stop and go, using AC, I will try to change gear late, let the rpm between 2k-3k, try not to overload the engine.


My owner's manual on changing gear is

upshift 1,300 - 2,500 rpm.

down shift 1,000 - 1,500 rpm.


my cruze eco (1.4L turbo) 6 speed manual gear ratio is

1 4.27
2 2.16
3 1.3
4 0.96
5 0.74
6 0.61


the rest cruze (1.4L turbo) 6 speed manual gear ratio is

1 4.27
2 2.53
3 1.47
4 1.07
5 0.87
6 0.74


Notice that the eco has three over drive gears (0.96, 0.74, 0.61), the last gear ration is high (0.61). I think the gear pattern also plays roles in the cooling system.