engine coolant temp too low?

[1990dsmkid]

Heys trying to figure out what temp range car needs to run in. Right now I have a vrfs fmic with no ducting, cx racing 2 row aluminim radiator, new rad hoses, newer heater core and a 180 tstat. During the summer my gauge reads 180 and up but I keep it under 210 with fan wired to a switch. Well now that the air is getting cooler my temp stays around 180-190 for the most part. Is 180 too low to be running all the time? Temp is read by an autometer short sweep electrical gauge. Thanks for the helps guys

 

[eclipsyco]

Mine runs around those temps (180-190) all the time I'm not saying is the best but I really don't see any problem at all.
Also where do you have that gauge (the sensor) hooked up!?

 

[1990dsmkid]

I have the sending unit installed where the factory one was. I no longer have or use factory gauge

 

[BogusSVO]

Too low of a coolant temp will cost you power, gas mileage, and cause accelerated cylinder wear.

Too cool and you do not get all the thermal efficiency from the fuel you burn.

On most cars, since the early 70's, the engines have been designed to run about 200*-210*

 

[1990dsmkid]

So your saying I need to put a stock 190 tstat back in and let it run and just dont let it get too hot but that brings up the question of what is too hot? I know I dont like seeing my gauge get close to 210 but if its safe then when should I start to worry and throw the fan on?

 

[BogusSVO]

Water boils at 212* at sea level

For every pound of pressure the rad cap holds you can add 3*

A stock DSM rad cap is rated at 13 psi

So

13 x 3* = 39*

now

212* + 39* = 251* would be your boil over point (Assuming the cooling system is in perfect shape)

I have read on the fourm, I do not recall the thread, at what temps the ECU turns the fans on and off.

 

[jayson427]

So me running a 160 t stat on a 10.5 compression is not good?

 

[BogusSVO]

195*, 180*, 160* thermostats, that is the temp point they are fully open. NOT what temp the engine will run.

So the sooner they are fully open, the longer it will take to reach op temp.

Size of the rad, and air flow over the rad, and temp settings of the fan(s) will dictate what temp the engine runs.

 

[1990dsmkid]

ok Thanks Bogus. Guess im going to have to change my tstat and not worry so much about the temp gauge hitting 210

 

[boost97gst]

anywhere from 180 and 210 is fine. Even the low 220s are ok, not ideal but ok. At, IIRC, 210* the ecu will pull some timing. You dont necessarily need to swap tstats all the time. Slide a small piece of cardboard to cover 1/4 of your radiator in the colder months. That should do the trick. Ever see 18 wheelers with the tarps that they cover their grill with in the winter? Same theory.

But, our tstats ARE extremely easy to get to so , get ya a summer tstat and a winter one .

 

[1990dsmkid]

idk what Im guoing do. Kinda getting mixed feelings here on what temps need to be at. I want my car to preform at its best and get the best milage I can and sacrifice as little as possible

 

[JFZERO ECLIPSE]

Listen to BogusSvo,

I would throw a factory t-stat back in to run at a little warmer temp as the ecu doesn't enter "learn mode" until it it at a minimum of 190*

 

[eclipsyco]

Copied from an old gofer's post:
For a 1g ECU to enter learn mode ALL must be true:
Coolant temp > 190F
Intake air temp < 123F
Baro > 22.9 inHg
Baro < 31.6 inHg

So sorry if I gave wrong info follow Bogus advice for your 1G
I know for a fact tho that 2g is:
Enter ECU Learn Mode: 180F (82C)
Coolant Fan ON: 210F (99C)
Pull 1 degree timing: 206F (97C)
Pull 2 degree timing: 224F (107C)
Enter Open Loop Mode: 228F (109C)
Default Coolant CEL : 235F (113C)
A/C Override: 240F (115C)
So my temps are normal notice please that those temps are while cruising at idle or hard pulls it goes as high as ~205-210.

 

[kamikazeredneck]

I would not recommend changing the thermostat. The stock temp is what that engine is designed to run at. Putting a thermostat in that is lower will reduce the engine life up to 10% for every 10* difference in temp from stock the thermostat that is run. If you change your thermostat and it fixes the problem then you are actually masking a more serious problem in the cooling system. This is a common problem is old V8 engines like the big block chevy.

On our cars the best operating temp is : Lowest: 193* highest: 206*
Although these are the optimum temps, not the max or minimum. Our cars will run fine at 210* like others have said but the fan turns on and the computer removes a degree of timing to put the temps back between the "ideal" range. It is the same with temps below 190*. Under 190* your engine puts in more fuel and increases the idol to get it to optimum operating temp. Max and min temps are not the same for every engine especially when you change things inside the engine over stock.

If your car is running between those temps then you are fine and do not need to change anything. The tune for your engine runs the best between those temps and keeps your engine running for the longest amount of time.

As others have said before, if your car is running too cool during the winter then block off part of the radiator or radiator intake. But please as a courtesy to other motorists please make sure, whatever you use to block off the radiator, is secure. Start out blocking off a small portion of the radiator and get bigger as needed.

195*, 180*, 160* thermostats, that is the temp point they are fully open. NOT what temp the engine will run.

This is absolutely correct. The opening temperature of the thermostat is what the temperature ratings means when you are talking about the thermostat.

So the sooner they are fully open, the longer it will take to reach op temp.

It can also cause other engine issues to be running the engine at non-operating temperatures. You want to do as much driving at the operating temperature of your engine to keep your vehicle running for as long and best as possible. This is why they do not do (or shouldn't be doing) dyno tests before the engine is up to operating temperature (this means the oil as well). This also applies to compression tests.

Size of the rad, and air flow over the rad, and temp settings of the fan(s) will dictate what temp the engine runs.

Another factor which is often left out of cooling discussions is the size of the radiators pass tubes and fin density.

The "pass tubes" are the size of the tubes that the go from one end tank to the other. The fins then are attached to these tubes. Yes that is correct, the tubes are what the coolant runs through not the fins themselves. The larger the tubes, the more heat being dispersed into the fins which get cooled by the air passing by them.

The next thing is "fin density". This is how many fins are in a given area. The denser the fins, the more cooling capacity the radiator has. Unfortunately you cannot run too dense of fins because then the air cannot pass through the radiator and effectively cool the fins.

This comes to another point, the amount of "rows" the radiator has. A "row" is considered one set of tubes running from the end tanks. When you add another "row" it puts another set of tubes either behind or in front of the first set of tubes. This makes it a 2 row radiator and it can keep doing this over and over. Back in the day everyone used to say the more "rows" the radiator had the better it cooled the engine. Well now days we have figured out that it is better to run less rows and bigger tubes. This is because of the fact that by the time the air from the first set of rows hit the last set of rows, it would be almost the same if not the same temperature as the coolant inside the tubes, which would not cool at all. This also applies to the thickness of the radiator. Just because your radiator is thicker does NOT mean it is going to cool better then another radiator that is thinner. (there are times when it being thicker is better but that is for another discussion)

The last part of the radiator is the number of "passes". A "pass" is referring to how many times the coolant goes from one side of the radiator to the other. Inside the end tanks of the radiator is chambers. When there is only one pass on a radiator then the end tanks have no chambers. This means that the coolant passes from the inlet end tank to the outlet end tank only once. When you have two passes then there are chambers in the end tanks separating the coolant. This allows the coolant to pass from one side to the other then back. This allows the coolant to pass through another set of "pass tubes" that send it through the radiator again before going back into the engine. This, in turn, allows the coolant to pass through the fins yet again to further cool the fluid.

Your fans are there to help draw the air through the radiator when at slow speeds or when there is not enough air being drawn through the radiator naturally.

When the radiator is working properly this is an extremely effective system to cool the coolant in the cooling system of the engine. This works just the same for any type of fluid cooling system on your vehicle whether it be the oil, transmission, power steering or engine cooling system.

If you are running into a situation where you are running too cool like the OP seems to be, it can be caused by a couple of things. 1) the cooling fans are staying on, pulling more air through the radiator than necessary. 2) the thermostat opening temperature is too low and allowing the engines coolant enter into the radiator even when its temperature is below optimum operating temperature. This brings me to another crucial part of the engines cooling system, the thermostat.

The thermostat is a device that stops or allows the flow of coolant from the engine to enter into the radiator. The thermostat for a given car is rated in *F or *C. This temperature rating dictates when the thermostat is designed to open and close. If say our cars have a 190* thermostat. This would mean that the thermostat is designed to open, and allow coolant to flow into the radiator at 190*. Any temperature of the coolant below 190*, say 189* or less, the thermostat stays closed and does not allow coolant into the radiator. This thermostat is there to allow the engine to warm up to its operating temperature (in our case 190*) before it needs to be cooled or sent into the radiator for cooling. During the time that you are driving your vehicle, the thermostat is opening and closing to keep the temperature of the coolant, and subsequently the engine, at its optimum temperature.

I hope this help you understand some of the different parts of the cooling system of the engine. In the case of the OP I would suggest changing the thermostat back to the 190* for use in all weather and season conditions. If you are having cooling issues during the summer (but judging by your OP I doubt you are having any) then your cooling system needs some attention. If you are constantly going above the 220* mark during the summer, then there are many other things you should do besides changing the thermostat to a lower temperature unit. If you have questions, would like to know more about the cooling system, or are having overheating issues and would like to know what you can do, please feel free to send me a PM and I will get back to you.

 

[1990dsmkid]

Im deffinetly going to have to change my tstat back to a190 when I get the chance to. If during the summer months my car does overheat then I should be good by just adding ducting for fmic and radiator. One more thing though, my temp only seems to really raise when Im sitting at idle obvisouly or when going up a big or long enough hill. Is this normal? I figure it is due to more load on the engine. From everything said thou Ive never really gotten that hot its just me not knowing 210 is save temp.

 

[eclipsyco]

Man just to keep it simple keep your temps between 190-210 either idle or cruising and hills.
Hard pulls is normal to rise above 210 but usually drops pretty fast to normal temp again.

 

[boost97gst]

This got way way complicated for a tstat question.
First, i didnt notice you are a 1g, learn mode is 180* in a 2g. My bad.
IDK why, but my Stant 170* manages me through cold temps and 100*+ days. I dont get too cold nor too hot, Im sure if i had really good ducting and it was 10* out my freeway temps might dip below 180* but i havent had the problem yet.

Bogus knows what hes talking about, do as he says and things will be ok. We all have to duct when going with fmics or aftermarket manis with no heat shields so that would be on my to do list if i were you.
GL

 

[kamikazeredneck]

It is completely normal for temperatures to rise a little but as long as it is controlled and not going past around 215-220*. You shouldn't be seeing sustained temperatures that high though but it doesn't seem like you are having that problem at all. When you turn your fan on it should be cooling the car down after long pulls and keeping it stable during. As long as it's not rising rapidly and staying between the temperatures stated, you will be fine. I wouldn't worry until the CEL comes on, going to hurt, which if your computer still has the stock setting, is not going to hurt your engine at all.

I apologize about the extensive reply, but the more information you know the better decisions you will be able to make further down the road. I wanted the OP to realize that not only is the thermostat a big piece of his cooling problem but also the fact that he has an upgraded radiator makes a huge difference. Now I understand not everyone might have the same opinion or like the extensive post but there is no harm in knowing more information and making an educated decision. I have gotten a PM from Bogus to make this info available in the tech posts so I will be creating a full tech post on the entire cooling system to the best of my knowledge about it. I have delt with multiple cooling issues with all kinds of engines from old BBC to new modern closed cooling loops, but I am no where near an expert so I welcome any and all help in these matters. I thank Bogus for asking me to make this a tech post as I was unsure if it was something that others would benefit from.

 

[eclipsyco]

^^^ Is a good and informative read don't apologize bro!

 

[JFZERO ECLIPSE]

I told ya Jordan , stock t-stat ftw...

 

[93AWDDSM]

Sorry to bring this back.today is 55* out and My temps are in the 165-185 range when the temp gauge shows operating temp. Lower range is when heater is on, I can’t get into the 190+ and stay there. I never see 200+, I’m going to try and change thermostats because the ecu needs to see 190*+ to get into learn mode correct?

On WOT pulls to 5.5k temp still only gets to 189-195*

 

[motomattx]

Unless your running engine management that you set the point at which the closed loop occurs, then yes it updates the trims at that factory set temp, alot of people change that in the ecu to whatever they want. Put it this way, as a technician most of my life so far, I have never seen an engine damaged from running "too cold" , however I have seen plenty get replaced from running TOO HOT! If your car cools properly in the summer leave it alone, we have had some super cold unusual weather lately and even my stock VW has set a code daily for engine cooling performance, there is nothing wrong with the car, its the fact that its negative temps outside.

 

[93AWDDSM]

No. I’m engine management I’m stock. Wouldn’t not getting into learn mode cause excessive gas usage? I’m just worried about properly getting into closed loop when I’m in cruising with such low coolant Temp.

 

[motomattx]

It COULD but not neccesarily, how is it currently doing?

 

[93AWDDSM]

Well, I’ll record a log of just normal driving in an hour. I replaced the fuel filter and replaced the t stat with a 192* one even though the one I pulled out was 192* also. I’m wondering if my coolant temp sensor could be off?