Thermostat going symptoms? what causes this?

[281pony]

i think my thermostat is going out, or something is fishy with my cooling.

today it is raining out, about 40 degree's or so i would guess. my car ran hotter today then it does in the 80 degree weather we had this past weekend. this is what happens, best i can explain it.

i drive the car like a grandma 98% of the time, and in the city usually. no matter what the weather, it seems to stick around 170 degree's. with alot of stop and go i see 175-185 TOPS.

so today with the weather i stated, i had a little fun going around some corners. spinning through the first few gears at about 1/4 throttle, controlled rpm's, never even saw my 4500 rpm shiftlight come on. car went up to 180 and stuck there for about 30 minutes of driving.

i stop to get some food, and it goes to 185 slowly. im waiting at the window for it, and it jerks over to 192ish, then 195.. i shut the car off thinking something is wrong. i get my food finally, by this time the car has heated up to 205.

i start it, and almost immidiately, it has dropped back down to 180 and stays there. wtf makes the temp all the sudden decide to jump? my running temps are inconsistant with the temps outside. sometimes the car will barely heat up when shut off, and jump like 5 degree's, and other times it jumps up like 30 degree's.

most of the time i never even see 180 degree running temps when warm, it is just very inconsistant. does this sound like a thermostat problem? ill list my cooling specs:

stock radiator, 170 degree thermostat, edelbrock mechanical waterpump, removed ac unit infront of radiator. temps off an autometer gauge on front of intake.

 

[DMAN302]

I'm not even intrested in the Temp untill I see 210*. With my Eddy pump and 180Tstat I am now in the very low 180's. You could change your stat out, but I know the EEC really doesn't like anything under 180*..or so I have read. At this point I would keep an eye on it..check the system for air, and continue to drive it..seeing if she acts up as the temps outside start to get higher.

 

[pwcracer]

When I had stat problems I wouldnt have heat a lot of the time.

 

[281pony]

that was the first thing i did. turned on the heater to see how it affected temps and if it was working even. it was hot and the temps didnt rise anymore.

i know the car isint necessarly getting "hot". im just wondering why some days it runs cold, and some days almost normal temp. seems like the thermostat is staying open at times and at other times maybe opening like it should

it has always run cold, before i did my 331 it never got over 160 degree's. maybe i will get a new thermostat and see what happens. just seemed like the thermostat would be the most likely cause for the inconsistant temps. thought maybe someone had a similar experience. i do always get the weirdest crap with my car though, or i am too paranoid over everything.

 

[ill advised]

Like DMan mentioned it sounds like there's air in the system and it needs to be "burped". Let the car idle with the radiator cap off and the heat on. If there is excess air in the system the car will literally start throwing up antifreeze. It may overflow then drop down a couple times. Let it idle until the antifreeze goes down and stays down, then add more water/antifreeze.

 

[67coupe]

Generally, t-stats usually stick open. I would suspect your t-stat if when cruising on the hiwaay, your engine temp is below the rated temp of your stat. Is this a "regular Auto-zone stat? The cheap $3 one. If it is, I've had many problems with them. I always upgrade and get the hi-po one ($7). As DMan mentioned, I would check your system for air first.

 

[vristang]

I have always suspected the t-stat first when having cooling problems, but have yet to see the t-stat actually cause any problems. If you did not have any problems before the motor swap start looking at things you changed with the motor. First the stroker will have greater cooling requirements than stock, but not so much that you would overheat. Did you re-route any coolant lines? Did the radiator go in with all of the same hardware? If you left out the rubber mounts on the bottom the rad, it will sit lower in the car. This could leave a high spot in the cooling system in the motor or the heater core/lines. That High spot will collect air pockets which will periodically block coolant flow. The temps you describe are nothing to worry about. When you run the car hard you build up heat in the block, heads, etc. If you do stop running at rpm quickly the coolant flow will reduce before the heat can be reomoved from the motor. The same kind of problem can occur in turbos. This is why a turbo car should be run at idle for a couple of minutes before shut down

 

[HISSIN50]

in addition to the good stuff already mentioned......

the stat regulates temps, whether the ambient temps are hot or cold. said another way, when it is cold out, the stat helps keep the motor warm. running at 180 (per the driver side lower intake location) with a 180 stat is great. and it is normal for temps to creep up after the car is shut off (heat soak and depressurization of the cooling system).

based on my quick scan of what you said, i would actually want to make sure the fan is up to par - that temp rising is what jumped out at me most.

a stat swap is always a nice idea. i am a fan of Mr Gasket stats. very nice pieces. 10 bucks at local speed shops here or under 9 bucks at online speed shops.

good luck bud.