Should my coolant temp ever pass the t-stat temp?

[mitsuman47]

Searched a bit, and didn't really find anything.

My car ('01 civic non-vtec) has a thermostat that begins opening at ~176f and is fully open at 195f. My scangauge will show coolant temps in the 200-213 range pretty often in the summer. In the winter it stays in the low 180's. I've changed the t-stat, burped the cooling system, and the car runs fine.

My question is, is it ok to go beyond the design limits of my cooling system? I mean, if Honda put a 195f thermostat in there, should I ever see temps higher than that if the car is in good shape?

I hope this makes sense. Thanks for the help.

 

[Oldwolf]

Most modern electronic instrument panel gauges are filtered so that they stay at one position during all normal driving conditions. If the engine really does begin to overheat the needle will then begin to move to the red. Today's "gauges" are really no more than "idiot lights". Most people are unconditioned these days to see the temperatures swing up during high load or high ambient temperature conditions. Manufacturers have found that a steady gauge needle makes people content and reduces the complaints they get.

Your scangauge on the other hand, is shown real operating conditions. The coolant you have in your engine allows the temperatures to get up to 240F or higher before boiling occurs. You are OK in my opinion.

 

[John K]

I would only be concerned if the cooling fan didn't kick on when temperatures increased. I've had some cars that the fan would only kick on when idling, when moving the air movement through the radiator was sufficient to keep it cool.

 

[Trav]

Very common and normal to see numbers in the 205-220 degree range for vehicle of this type.Vehicles fitted with electric fans generally don't turn the cooling fan on until a point after the thermostats operating temp is reached.

Even though the thermostat is fully open it takes a few minutes for the whole system to drop back down after the fans start or the vehicle begins moving to push air through the cooling fins.

The engine is designed to operate with this temp fluctuation.
Unless it appears the engine is inevitably going to overheat(gauge heading dangerously close to the red) or the electric fans are non functional then this fluctuation can be considered normal.

For you own peace of mind you can check the system.
1)Check the coolant level
2)Check the thermostat to insure its fully opened at the specified temp.
3)Make sure the electric fan comes on when the a/c is turned on when the engine is at operating temp.(if the system is designed this way,check the service manual)
4)Check the fan sensor,make sure the fans are starting at the specified temp.

IMO you seem aware of this so just keep an eye on it.I wouldn't get to carried away testing.As with any cooling system concerns keep an sharper than normal eye on the coolant level until you feel comfortable that this is normal for your engine

 

[IndyIan]

Your car is running normally, I have a scangauge too and see temps abit above the fully open temp of the thermostat(195F). At 212F the cooling fan kicks on and at 200F it shuts off. Keep in mind as the temperature of the coolant increases it transfers more heat out of the engine so unless you are seeing temps that aren't dropping when your fan kicks on your car is fine. Just follow the schedule for your coolant changes and you shouldn't have a problem.

 

[Cup of Joe]

You are fine. If the fans quit working then you have a problem. I just had the fan relay go out on my Grand Caravan so temps climbed as high as 240's before the coolant gauge moved on the dash. When I hooked up the Scanguage it was 230's and no fans. I drove it to Carquest (50 miles) and was fine until I got in town and temps started climbing into the high 230's again. With the overpriced solid state relay fixed the fans come on at roughly 213's.

My Rio has a 180F thermostat and normally operates at 202-204 on the freeway. Its never higher then 207F in town without the fans coming on so it has a very small temperature window. Sonata I just bought runs 190 on the freeway and will go up to 213 or so before the fans come on.

 

[tomcat27]

Absolutely the car will see temps above 195. thats simply the temperature at which the thermostat is fully open. most cars will see temps from 200-210 in the summer, a few will run even a little higher.

 

[mechtech2]

Thermostats are rated by their opening temperature.
A 195 therm results in a car running at 205 or so.
Are you sure your rather new car's thermostat opens at 176? That is unusually low for a modern car - 195 is more normal.
This would explain everything.

 

[swalve]

The thermostat's job is to keep the coolant temperature *above* the set point.

 

[mitsuman47]

Thanks for the help guys. I'm feeling a little better about it.

One thing to add, though: You guys keep saying stuff about the fans coming on and all that. But, when I see the high temps, it's when I've been on the freeway for awhile. When I'm just sitting in traffic, its fine. Stays at 180 with the a/c on (fans on constantly), and goes up to about 206 with the a/c off (fans on intermittently).

Would this change anything? I mean, I'm not relying on the fans at highway speed. And, I'm actually seeing sustained temps higher than what is needed to turn the fans on.

 

[mitsuman47]

Originally Posted By: swalve
The thermostat's job is to keep the coolant temperature *above* the set point.


I had always thought it was there to keep the coolant in a certain temperature range. No?

 

[mitsuman47]

Originally Posted By: mechtech2

Are you sure your rather new car's thermostat opens at 176? That is unusually low for a modern car - 195 is more normal.


Yeah, I'm sure. I bought the $125 factory service manual that the honda techs use. It says begins opening at 176f and fully open at 195f.

 

[swalve]

Originally Posted By: mitsuman47
Originally Posted By: swalve
The thermostat's job is to keep the coolant temperature *above* the set point.


I had always thought it was there to keep the coolant in a certain temperature range. No?


Nope. The cooling system as a whole keeps the coolant in the range- the thermostat keeps it from going too low, the radiator and cooling fans keep it from going too high.

 

[IndyIan]

Originally Posted By: mitsuman47
Thanks for the help guys. I'm feeling a little better about it.

One thing to add, though: You guys keep saying stuff about the fans coming on and all that. But, when I see the high temps, it's when I've been on the freeway for awhile. When I'm just sitting in traffic, its fine. Stays at 180 with the a/c on (fans on constantly), and goes up to about 206 with the a/c off (fans on intermittently).

Would this change anything? I mean, I'm not relying on the fans at highway speed. And, I'm actually seeing sustained temps higher than what is needed to turn the fans on.

Atleast on my Neon the AC rad is over laying the engine rad so when the AC fan kicks on it pushes air through both cooling the engine too. Sounds like your car is setup the same.

 

[Trav]

Originally Posted By: mitsuman47
Thanks for the help guys. I'm feeling a little better about it.

One thing to add, though: You guys keep saying stuff about the fans coming on and all that. But, when I see the high temps, it's when I've been on the freeway for awhile. When I'm just sitting in traffic, its fine. Stays at 180 with the a/c on (fans on constantly), and goes up to about 206 with the a/c off (fans on intermittently).

Would this change anything? I mean, I'm not relying on the fans at highway speed. And, I'm actually seeing sustained temps higher than what is needed to turn the fans on.


The A/C turns the fans on automatically.At highway speeds the engine is being cooled by air being blown over the radiator fins.206 degrees is fine and nothing to worry about.What you describe is normal operation.

 

[mechtech2]

When a thermostat is open, it is open.
It doesn't matter if it is a 160 or 195. So very high temps like 220 means any thermostat is already open all the way.
Things to check are belt tension for the water pump [not sure what system is on your car], oddball water pump impeller blades being loose or corroded internally [tough to figure this one out!], partially plugged radiator, or a coolant system low on fluid or a faulty thermostat.
Get a good factory thermostat first, and go from there.

 

[The_Jeff]

I would check under the front bumper and make sure all the factory plastic stuff is still there. The goofy spring loaded shrouds on most cars get ripped off by parking curbs. They matter.

It's also very possible the coolant temp sensor is significantly far from the thermostat... so high water flow rates or high heat rejection rates have differing effects on each part. My dodge spirit had its thermostat on the engine outlet and dash gauge sensor on the inlet-- in winter when the car was working HARD going up a hill etc the thermostat opened wider, increasing flow from the freezing cold radiator and making my gauge DROP. Wierd, I know.