Running without a thermostat ok?

-

sargentrs

Well-Known Member
Joined
Aug 9, 2014
Messages
436
Reaction score
31
Location
Jasper,GA
Few months ago replaced the radiator, water pump, thermostat, hoses, etc. Had a 160* thermostat and when cold weather came in, upped it to a 180* to get more heat flowing. She's always run around 180*-185*. As the temps rise, I've noticed she's running hotter as the heat rises. When it was 80* she ran about 185* 85-90* outside, it started rising to 190*. 90-95* around 195*. Temps hit 97* today and she ran as high as 200*+. Same road, same driving every day back and forth to work. No sign of lower temps so I expect it to just keep climbing. Everything seems to be working ok, she cools down at 45-50mph and idling at stop down to around 185+* or cruising on shady roads. As she starts uphill and I maintain speed, the temps start climbing. Question is, is it ok to run without a thermostat or should I just drop it back down to a 160* and see that provides enough coolant flow to keep her down to under 200*? I expect 100*+ temps in a couple of days. Any and all input is greatly appreciated.
 
I have heard people argue both ways. Personally I got tired of the cheap parts store thermostats freezing up every single year after the car sat all winter. I took a thermostat and gutted the spring and diaphragm, but still run the housing to restrict enough water to somewhat simulate the thermostat being open. Been working for me just fine. Car seems to run at 170 despite ambient temp. Thats one opinion. Hope it helps.
 
I hear where you're coming from, it looks like we're in for 95/100 degree temps for at least another week :banghead:.

I personally would not pull the stat with the scenario you wrote about. You actually have pretty normal temps for a standard cooling system. As long as you're running close to a 50/50 mix of coolant, I seriously doubt if you'll get close to a boil over situation.

As spoken of above, you do need "some" restriction in flow...especially on the highway. You gotta keep that coolant in the radiator long enough for it to do it's job.
 
If it overheats with a properly functioning thermostat, it will overheat without one. If the thermostat does not open, replace it. Changing back to a 160 shouldn't make any difference. Since the engine cools with the car moving, it would seem that the radiator and thermostat are functioning properly. Heating up in traffic on a hot day isn't abnormal, and 200 is just fine. Take a good look at the fan and fan clutch, and fit a shroud if not equipped.
 
No. It's not ok.

I wouldn't

I hear where you're coming from, it looks like we're in for 95/100 degree temps for at least another week :banghead:.

I personally would not pull the stat with the scenario you wrote about. You actually have pretty normal temps for a standard cooling system. As long as you're running close to a 50/50 mix of coolant, I seriously doubt if you'll get close to a boil over situation.

As spoken of above, you do need "some" restriction in flow...especially on the highway. You gotta keep that coolant in the radiator long enough for it to do it's job.

If it overheats with a properly functioning thermostat, it will overheat without one. If the thermostat does not open, replace it. Changing back to a 160 shouldn't make any difference. Since the engine cools with the car moving, it would seem that the radiator and thermostat are functioning properly. Heating up in traffic on a hot day isn't abnormal, and 200 is just fine. Take a good look at the fan and fan clutch, and fit a shroud if not equipped.

^^This and verify your tune.
 
As spoken of above, you do need "some" restriction in flow...especially on the highway. You gotta keep that coolant in the radiator long enough for it to do it's job.

Sorry this is not true. You DO need a stat but "keeping it in the radiator" is not the reason.
 
no thermostat lets the water run too quickly through the radiator for proper cooling leading to water that hotter than it should be back into the engine. Like another poster here said, at least gut a thermostat to replicate the restriction to slow the flow
 
no thermostat lets the water run too quickly through the radiator for proper cooling leading to water that hotter than it should be back into the engine. Like another poster here said, at least gut a thermostat to replicate the restriction to slow the flow

I keep trynnna tell you this. It ain't true. If an engine overheats without a stat it is NOT because "it goes through the radiator" too quick. However, you are right in one respect.......a stat, a good one, should be in place.
 
Take a good look at the fan and fan clutch, and fit a shroud if not equipped.

Also a good thing to look at if your temps don't stabilize until you're 45-50mph...
 
The thermostat only sets the minimum running temp.If your engine runs hotter, the rest of the system is unable to shed heat fast enough, or the engine is, for some reason, creating more heat than it ought to, and the system is unable to shed it.
 
The thermostat only sets the minimum running temp.If your engine runs hotter, the rest of the system is unable to shed heat fast enough, or the engine is, for some reason, creating more heat than it ought to, and the system is unable to shed it.

Well, no matter how hard you try to tell some of THEM that, THEY just will not listen.
 
Thanks for all the input guys. The thermostat stays then. Good, I didn't feel like changing it anyway. This being my first slant, I'm not familiar with what is considered "normal" as far as water temp is concerned. So 210* is not unusual or too hot?
 
Thanks for all the input guys. The thermostat stays then. Good, I didn't feel like changing it anyway. This being my first slant, I'm not familiar with what is considered "normal" as far as water temp is concerned. So 210* is not unusual or too hot?


210 ( if it was there a lot)is a little hotter than i would be comfortable with but im sure somebody else will chime in. im not a wizard at cooling systems ( or anything lol) but i believe as long as it cools off when you slow down or stop then its not really ( what most people would consider)overheating. i am not sure about gutting the stat for restriction but have heard a lot of people do it so maybe and i did not see it above anywhere so maybe somebody will answer that one or maybe they did not answer because its a stupid idea lol

now off to read the above link that i prob should have read before replying lol.
 
The trick here is to get the cooling system to opperate well enough that it tries to close the thermostat. I doubt the length of time coolant stays in the radiator will matter much, as the longer it cools in the radiator, the hotter it gets in the engine. Heat transfer and fluid flow equations I'm sure will bear this out. After the engine reaches 200 degrees every typical thermostat will be open all the way and stay there, no matter its rating, and if it is functioning correctly. You now need the system to keep up. Make sure the radiator is clean and not blocked, hoses are not collapsing, block is clean, fan is correct and belt tension is proper. Shrouds seem to help, but I have had good luck without them, however I do eliminate the clutch fans. They will slip a little under hard acceleration so as to allow a little more power to the drive train, but I always figured that's when I needed the most cooling.
 
well.....in the 50's/60's people would regularly remove the stat for the summer. Mainly a stat restricts waterflow to enable an engine to heat up quicker so as to get heat sooner out of the heater core. But...with a high flow pump..it can flow too fast for it to cool properly. I run a 160 stat with a small hole in the stat. Works for my hemi in hot weather
 
Run a thermostat. Without one coolant will flow freely at max flow all the time. AS stated, the coolant will not retain the heat in the engine and will flow too quickly. It will take longer to warm up and result in loss of performance and fuel mileage.
 
Can we assume a new radiator cap went on the new radiator ? Does oil pressure drop very low when the engine gets hot ? Oil flow does effect engine temp
 
Does this make sense as a general rule?
Hot at idle. Look for an airflow issue.
Hot at speed. Air flow has increased, look at fluid issue.
 
Does this make sense as a general rule?
Hot at idle. Look for an airflow issue.
Hot at speed. Air flow has increased, look at fluid issue.

No, it can have a fluid flow problem at any speed or temperature, unless there is no fluid.
 
Can someone explain why some people say an engine without a thermostat will overheat? I don't entirely believe that because an engine with a thermostat stuck open runs cold from my experience. I read the information in the link above, interesting read.
 
Can someone explain why some people say an engine without a thermostat will overheat? I don't entirely believe that because an engine with a thermostat stuck open runs cold from my experience. I read the information in the link above, interesting read.

Except for a thermostat stuck closed they overheat for pretty much all the same reasons with or without a t-stat.
 
-
Back
Top