when im stopped at a light, for example, the gauge reads where it should. now as soon as i start driving it starts to drop. the faster i go the more it drops. If im doing like 60 mph, its below the cold mark. lol. then if i stop, it little by little comes back up to normal operationg temp.

I got some custom ducting into the enginebay, a vented CF hood, and Waterwetter additive in the radiator coolant. Even still, the gauge or the sender must be wrong, right? BTW its a 2002 Lancer es

thanks for any help.

 

I would assume it goes down the faster you go because the air is moving faster and faster thus it cools more and more. Try flushing the radiator and using regular old radiator fluid without cooling additives, you might be over doing it.

 

Do the temp gauge even go above normal operating temp?
If it doesn't, don't worry about it.
Ambient air cools your motor better when you drive since you've got all that ducting and vented hood.

 

It also possible that you have a termostat that is stuck partially open.

 

I figured it would drop SOME but the gauge goes ALL THE WAY PAST COLD. lol BTW i didnt know you could over-cool your engine. he he

 

+1.

 

shouldnt the colder air mean more performance? ;D!

 

going that low is kinda wierd you should notice a drop with the water wetter i use it noticed about a 7-9 degree difference. You could do a pressure check on the radiator just to be sure but i wouldnt worry unless it begins going the other way hahah

 

Original gauge cluster? If it is, and it's always worked fine before...eh, maybe that water wetter is God's gift to your cooling system???

 

Very good point

 

NO NO NO! Colder is not better. Hot is bad, so is bad. Wear increases greatly, and fuel economy suffers horribly. If your thermostat and temp sender are working properly, the coolant should be in the vicinity of 190-210 degrees all the time, regardless of vehicle speed.

Your problem is caused by one of two things. One, it could be the thermostat. They are cheap and easy to replace (approx $5-10). Do that first.

If you still have a problem, change the coolant temp sender. NOT THE ENGINE COOLANT TEMP (ECT) SENSOR!! They are different. This is the gauge sending unit that affects the instrument cluster reading. These usually cost from $40-60 and are also very easy to replace.

Ignore what they said about removing the water wetter. An efficient cooling system relies on good thermal transfer (water wetter helps) and temperature regulation (an accurate thermostat). I am dealership mechanic and I have seen this problem before. I've also heard people say that they're not worried because low operating temps are ok. It's not ok, it's killing your motor and wasting your gas.

Yellance: Pressure testing is only needed in a situation where coolant is being lost. The problem he described has nothing to do with leaks.

 

wow lots of good info! Thanks!

Here are the new developments. I changed the thermostat and i still have the same situation. When the veh is moving, the temp gauge drops very quickly way below the C mark. As soon as i stop at a light it quickly comes back up to the middle of the gauge. I also comes down a little if i rev the engine while at a stoplight. There are no leaks whatsoever

Im thinking ima change the coolant temperature sender as mcgarvey suggested. Hopefully its just that the sender is just buggin out.

 

This happened to me a few months ago. It was the temperature sensor wire. Somehow it had corroded and broke off so every time the car moves a little and it would touch, my temp would go up like it was normal. Then I would go and drive the car and I guess the wire moved and disconnected itself causing my temp needle to drop all the way down.

 

ok now i got another question'

which is the coolant temp sender and the coolant temp sensor and where are they at?

diagrams would help, thanks.