your coolant works really good... :lol: (possibly) doesnt seem like its a problem if nothing abnormal is happening to the engine. Your engine must take in alot of cold air as its driving at faster speeds so maybe your radiator is working more as your going faster and less when its not moving.. seems kinda werid that it would do that though.. but doesnt seem like a bad thing at all

 

yeah...i don't think that i'd be too worried about that lol

 

Maybe an early sign the thermostat is about to go.

 

Maybe an early sign the thermostat is about to go.

I agree. Temps shouldn't vary that much. Your thermostat is opening but not closing like it should. Could be it is not closing at all and staying open. Have you noticed if it is taking longer than usual to reach "normal" operating temps? If this continues to the winter season, you might have very long cold rides before the engine warms up.

 

Maybe an early sign the thermostat is about to go.

I agree.

The thermostat is what regulates the temperature, the variation would suggest that it's staying open most of the time.

 

I think greylock and 500KCamry have hit the nail on the head. Your thermostat is not completely closing. A new thermostat and gasket (o-ring actually) should run about $10-$15 at the dealership. It should take about 20 minutes to change out and about 45 minutes to refill the coolant and then bleed all the air out of the system. This is a great beginner DIY project. Get a manual to help you through it.

Mike

 

Maybe an early sign the thermostat is about to go.

Not necessarily. I have a weird issue with my cam too. The temp gauge is all over the place. When at stop lights and stuff it'll drop to almost cold, then while in traffic it'll move closer to the normal operation temp, but will fluctuate as well from normal to cold.

I had a minor tune-up done recently (distrib cap, rotor, plugs, plug wires, fuel filter, and thermostat) and the problem still exists.

The guy that helped me do the tune-up (mechanic at my job) said that since the thermostat didn't fix the problem it's probably my "Coolant Temperature Sending Unit" but said it's not that biggest deal that I replace it cause it's kinda expensive.

So this might be what your experiencing too.

 

Yea, it's pretty weird, and it seems that Durrby's ride's doing the same (or at least somewhat similar) as mine. Warm ups don't take long (by my standards), including the winters, and the indicator needle never exceeds the middle, so I don't think I'm in immediate danger of damage. Nevertheless, I'll have a closer look under the hood today and I'll have my repair manual in hand. You never know what can happen next. Thanks for everything guys, and more input is more than welcome as I'll continue to read your guys' responses from time to time.

 

The coolant sensor isn't that expensive $75 CDN, I think. If that is the problem it should be changed cause it influences the fuel injector pulses. You fuel economy might drop, and your car (if I4) might be hard to start at times.

Also check your coolant level, when the car is cold take of the rad cap and fill if necessary. Put the cap on then fill the reseviour to the cold level. 50/50 water/antifreeze.

 

i think it's doing good, your thermostate should be okay, when you rev up to higher rpms the thermostate opens up more to let more anti-freeze in, so it would make sense that when your car gets to higher operation zones that the temp. gauge would read different measurments, i think all it's saying is that your car is doing what it's supposed to be doing, which is, cooling your car.

my cam has the exact same symptoms.

also my camry heats up real fast as well, by the time im at the end of my road it's about to the middle, between hot and cold (great for winter).

also thermostates are very very cheap as well.

 

Ya Think!

 

The thermostat and temperature sensor are separate. The thermostat opening/closing is controlled by water temperature, not coolant flow.

I don't like the cooling system on the I4 because if it's down a few cups of coolant it doesn't work properly. It's not very forgiving with coolant loss.

If you buy a new thermostat make sure it has a jiggle pin and when you install it, make sure the jiggle pin is on top (closest to the hood). The pin lets air past the thermostat when the thermostat is closed and for the I4, when the coolant is filled air can get trapped in the lower radiator hose that connects to the thermostat housing body.

 

I agree, try replacing the thermostat.

You may get better gas mileage once this is done. My Saturn behaved this way and everything was fine after replacing it, and I got better mileage to boot. On the Saturn, the computer looks at the coolant temperature and gives more fuel to what it thinks is a "cold" engine.

Should be a cheap fix; even cheaper if you do it yourself. Good time to change the coolant too.

 

It hasn't gone to the point where fuel consumption is dropping... yet. I've been averaging 26 mpg (too lazy to convert to L/100km) in mixed city/highway driving, which I think is good, EPA numbers are nothing but bull. I'm very curious to see how it behaves with A/C on (I almost never use A/C because it saps power). Last time I checked, my coolant level is OK, and I'm pretty sure it's a 50/50 mix, so chances are it's got a helluva cooling system, or it's the thermostat. I eliminated the coolant sending unit, as I'm pretty sure that's not the problem. I'll see what Toyota thinks of this during my next 5000mile service, which, thankfully is in a couple of weeks. This is awesome, keep 'em coming!