THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

Hey. Just looking on some other opinions about thermostats. Running a b18c turbocharged right now. The car overheats on the highway, but not in the city. Now I have a Mishimoto x-line 3 core radiator (hella thick :tobes) and my fan is on constant, but on the highway, with about 20 minutes of driving, it hits the 210 degree mark. My question is targeted at the thermostat because I never thought of it to be a problem before, but as I'm sitting here at work, it dawned on me. I have a Mishimoto low-temp thermostat that opens at 68 degrees Celcius (roughly 154F). But if the coolant in the radiator is 160, and the coolant in the engine is 160, doesnt that mean that the thermostat will STAY open until water/coolant that is less than 154 degrees hits it? if so, that means my thermostat would be staying open and the same water would just be circulating through and through without a chance to stay in the radiator and get cooled down properly, right? ....starting to believe this thermostat may be the issue and i need to replace it. I've replaced everything else...radiator, pump, hoses....even filled the system with supercoolant and water instead of 50/50...

re: THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

Any other modifications to your cooling system? Like deleting any hoses on the thermostat housing, intake manifold, etc.?

re: THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

My turbo projects all ran 'hot' , but stabilized at 200-205 . They did not overheat. I tuned for it knowing to adjust maps for higher temps and to use aggressive fanning. I decided my situation was not severe enough to change the cooling system.

Stock my Integra ran 192 F and my Accord 196 as a baseline.

If it keeps rising and the temps do not stop rising in traffic, your cooling system might simply have a pressure leak. More than just an improper tune. Lean or retarded.

Only water is the best coolant, better than water wetter or some snake oil.

Temps should stabilize at some point. If not you will hit boil over , and the heat cannot be controlled by cap pressure any longer. Water coolant boils at 218 F +10 degree per cap PSI.

The 160 spec is opening temp. I didnt understand the rest of that.

Is it truly overheating, boiling over with visible steam? Uncontrolled? If temps hold but at elevated levels, the cooling system capacity can be altered/increased , using custom radiators.

re: THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

If you're overheating on the highway, but not when stopped, then odds are you have an airflow/ducting issue.

Post a picture of your engine bay and the way your radiator is mounted. It sounds like air is being allowed to go around the radiator rather than through it when you're at speed.

Edit: Also, to add on - You do not need a low temp thermostat. I can't think of any reason to EVER use a "low temp" thermostat. If the cooling system is sufficient and doing it's job properly, the OEM thermostat (or OEM spec) should always be used.

re: THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

ive always gotten less knock at lower temps

re: THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

Yeah, this.

re: THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

Try to do a 20 minute trip by removing the thermostat all together.It looks like it opens
but it isnt able to open all the way so it can handle a low heat ratio but not a higher load that creates bigger cooling / time requirement.
IIt probably opens a lot lower % that it needs.

re: THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

If the thermostsat is suspected of hanging grab a pot of water, activate the stove to boil, and use a thermometer. Should be able to visiually inspect when it opens.

There is no overheating at highway speed, but not parked. So.. If it is ducting, then it won't flow doesnt matter when. Perhaps it is not driven far enough yet.

Sweep a temp gun on it, look for an obstruction in the system.

re: THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

It is very easy to have higher temps on highways and no overheat while standing.
The temperature comes from the rpm and load.
On the idle you have lets say 100 joule / minute heating of water, and on highway cruising 400 joule /min.
If the thermostat opens 2milimeters the water passing through might be enough to stabilise temp of 100joule/ min heating.
On the highway it may needs to be open 5mm to maitain balance on the heat to cooling ratio.
It can be reprodused but shuting the thermostat all together but making holes to it.
The key is the fan working on the idle.

re: THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

No. Im under the impression you believe it is not distance related. Fine.

Letting off the gas cruising at 65MPH , returns it to normal temps? I don't follow the condition. Thread poster, please explain with maximum verbosity.

You should not be getting any knock, is this new? My sensitivity is set real low in the parameters, my opinion is the factory knock sensor is not for performance tuning but a safety.

Were holes drilled in the thermostat prior to install?

re: THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

Lol.. Yeah.. Go ahead and run straight water and see how long your shit lasts. Water pumps will be destroyed over time due to corrosion. The boiling point of Ethylene Glycol is also much higher than you stated.. Its boiling point is 387°F. The efficiency of water cooling is ok, but depends upon the best possible contact between the surface and liquid. Problems with liquid cooling begin when the engine starts reaching the boiling point and bubbles start forming. These bubbles prevent proper contact between the liquid and engine surface, then the problem starts becoming exponentially worse..

re: THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

No sir. no other mods. No deleted hoses. None deleted on the IM. However, if i'm not mistaken, one is supposed to be running from the back of the head to the throttle body if I remember correctly (its been a long while LOL). That one is capped off on the back of the IM where it bolts to the head. Running an aftermarket throttle body (always have)

re: THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

only mod is the waterline that goes from the back of the head to the throttle body is capped off. Running a Skunk2 pro series

re: THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

It's odd because NONE of my projects before ran HOT, per se. Last one was an EF that was running a little warm, but I replaced the 1/2 radiator with a full sized one and never saw temps above 170...and before that, i had an EM1 Si with a Mishimoto 1/2 size...never ran hot. when my car hits 210 degrees, i get an engine light for overheating. and my problem is NOT that the temps rise in traffic, they rise on the highway. In traffic from A to B im good. I hit the highway and 10-15 miles later im hitting 209...and on the way back, cross the 210 threshold, thereby activating the MIL

re: THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

Im overheating on the highway...but not overheating during CITY driving, so really say im not overheating "when stopped". During normal driving, around the city or wherever, its fine. Stretch it on 95 for some miles and then we have an issue. Uh, the radiator is mounter the way its SUPPOSED to be mounted in an EG. :yum: Fan, and shroud included.

re: THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

right

re: THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

Think I'm going to actually secure a REGULAR thermostat. Removing the thermostat causes the vehicle to overheat as well

re: THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

yes this is also what i was thinking. I figured its the load of the engine, and the transmission I have is NOT making it any better LOL. Anyone got an LS tranny laying around for sale?

re: THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

no, letting off the throttle doesnt return it to normal temps. I'm not getting any knock. Where did you get THAT notion from?? No, I didnt drill any holes in the thermostat. The coolant system is pretty much stock, with the exception of the radiator and fan replacement, the replacement all fluid transfer hoses, and ONE hose being blocked off. The one that is supposed to go from the nipple on the back of the intake manifold to the throttle body. I have a Skunk2 Pro-series throttle body, which doesn't accommodate for fluid usage.

re: THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

If your engine is tuned with a OEM Thermo the OP temp will be at that temp, once you replace it with a Mishi thermo, the engine does not reach that OP temp as fast and will cause drivability and tuning issues, Bisi Moto is the one who told me this. I had the Mishi thermo and the temp would reach about 160 - 170 and I couldn't get the engine any warmer during the dyno, the tuner wanted it to reach about 180 deg and was explaining the engine is running a little too cool which was strange to him but I told him about my Mishimoto radiator, cap and thermo. We tuned it but I later replaced it with a OEM thermo and temp will rise to 180 for the engines OP temp. I still will retune it as it was never properly tuned that day do to other factors as well. But I think the OEM thermo is the best to have.

re: THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

Never reaching operating temp can be worse than overheating. That sounds like you had a bad thermostat and it was opening too soon.
Are you under the impression that runninng the engine under 180 F is beneficial? Those are running temps, not IAT temps. 1 thing at a time.

Shine a temp gun on the engine. It sees high temps.

I explained what overheating was. You are not overheating. You have your fuel maps wrong.

It is holding at 210? Not steam from under hood at shut down.

Can you smell coolant? Sweet smell..possibly means its not holding pressure and you have a leak in the system.

What RPM at 65MPH? With constant 65MPH air flow,nah.. What load is there at 65MPH cruise? Load condition is in the stop and go city. And he said it was not distance or time related.

re: THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

SMH...whether I'm under the impression that running the engine under 180 is beneficial or not it IRRELEVANT seeing has how my car is running 210+ degrees. Who is talking about IAT temps??? I'm talking about the temperature of the engine/coolant. I'm not ASKING if the car is overheating, i'm STATING that is is. So now my fuel maps are wrong and you are under the impression that I'm running lean, causing the vehicle to overheat? I guess 14-15:1 is no longer considered a good range to be in, outside of boost. NO, my temps are not holding at 210. If they were, I wouldnt have created this thread. I would just drive at 210. :shrug: But when I hit 215, 220...225, then yes, i'm going question it. No, i dont smell coolant. No leaks. No drips. Pressure tested the system already. I'm running a JDM GSR tranny, so my RPMS are up there at 65 mph. I'll figure it out...

re: THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

Its overheating, not leaking, ok. If you had it holding at 210 I would say try a larger capacity radiator.

I have not had to upgrade the cooling system at all. I'm at 1 bar sometimes 17-19 PSI in my projects.

My GSR I swapped in a LS 5th gear with the 4.79 final drive. That puts 5th gear 60MPH at 3000RPM. Might have some cooling effect.

Have any friends where you can look at their maps, see the duty cycles and timing map. Look at how much their fueling, for the size injector, at a power level. Im still thinking its burning lean for that long distance highway cruise temp change, running on the low speed maps while your not getting into it city stop and go. Or a leak.

re: THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

Have you tried giving it more fuel in order to cool it down?

That hose goes to the Iac and fastidle valve, as you know. Those systems handle fueling for the running conditions, adjusting for temp. You compensated for omitting this in the tuning software? Bigger throttle body, more air, it would be leaner at cruise without fueling.

re: THERMOSTAT...YES, THERMOSTAT *SOLVED*
 

I think you just need more air flow to the radiator.