Civic EG

So my cooling problem isn't that it overheats, it actually overcools if that makes sense. This is the temperature whenever i am driving down the freeway. This usually happens if i am in 5th gear and not pushing on the gas. It does have thermostat and this picture was taken after driving for 2 hours. I have a D15b vtec engine with stock everything. no a/c and no P/S.

My car did the same thing ALL winter. First off make sure you dont have your defroster on because that makes the fan kick on. Second have you replaced the thermostat recently? If not the thermostat if probably stuck open and unless its really warm out the car will stay like this. Does it do this in city driving to or just the highway driving?

If your thermostat is stuck open which you wont tell until you take it out, go buy a new one at the parts store, shouldn't be more then $25 with a new gasket and all. Thats where i would start. You should be able to use the thermostat out of the d16z6. Before you replace it i would get some boiling water on the stove and drop the new one in there and make sure it opens to make sure its not defective...

This only happens in freeway driving. even when the weather outside is 90 degrees. on city driving or stop and go, it stays right under the middle which is operating temperature. The thermostat was replaced a month ago so it isn't that.

Could still be the thermostat. There are plenty examples of brand new things being defective.

Do you have an over-sized radiator?

Radiator is stock and the thermostat was replaced yesterday just in case. I took it out for a long drive and it still does it. maybe this is my engine telling me it wants more compression

I want to say CLT. It's an usual problem, but if I were you, that's what I would try. Take a deep socket and pocket one from the junkyard. Many Hondas use the same sensor so they're not hard to find.

There's two CLT's and a fan switch. I always forget which coolant sensor is for your gauge, and which is for your ECU. One is under the distributor next to the one pin fan switch... now I can't remember off hand where the other is. Damn I'm getting old. I turn 31 in a few days.

too much coolant? not a 50/50 mix of coolant?

Blackdeath159 wrote:Radiator is stock and the thermostat was replaced yesterday just in case. I took it out for a long drive and it still does it. maybe this is my engine telling me it wants more compression

hate to ride you but did you check the thermostat before you put it in with boiling water?

listen to suspedhatch about the CLT.

Take a look at your radiator, from the backside (facing engine). is there green all over it?

Also drive down the highway till it gets this low, and pull over and pop the hood. The fan shouldn't be running at this low of a tempature so make sure it isn't running yet

I did all the test, i even took it to my local honda dealer and they cant explain why it cools so quick. They found out it will only do it going down hill when they weren't pushing on the gas. The engine is actually warm not hot after the temp goes down even though they have been driving it for a while. they let it warm up to operating temp. then they took it out for a drive and when they were coming back they had to drive down a hill and they noticed the needle going down so they pulled over and checked the temp. and it was at 101 degrees from 192 degrees when it was warm. They said that since i didnt have a condenser in front of my car, the wind helps cool down my engine

Blackdeath159 wrote:said that since i didnt have a condenser in front of my car, the wind helps cool down my engine

i call bs i have no a/c and no condensor and i dont have this problem goin down hills.. and if ur fan was on while drivin at high way speeds it would affect any thing

but that sensor is prob the reason it does that
ur thing says u live in riverside
id hit up pick a part off the 60 in fontana
for the sensor under the dizzy(the one wire)
or ecology in fontana they have 2309423094823094 hondas there..lol

did they tell u how they checked the temp?

all they did was point an infrared temp gun to the top hose. I call BS too cuz it didnt do this when i had my d15b7. well i went to pick a part and got 5 of those sensors. my first test didnt prove anything. it still went down. im about to give up on this. and if it is my sensor then why is my engine block still not getting hot?

damn i have know idea

ur rite how is it the sensor if the block isnt hot...

maybe ur cooling system is soooo freakin good it drops 100* down hill

there is only a few things in the cooling system
and if any of them are bad(but the thermostat if stuck open) the car overheats..

what kinda coolent are you runing?
unplug ithe rad. fan and go down hill..
i know its not the fan, cause i had my fan hard wired so it was always on when the car was on and i used to come down from moval to riverside that lil hill and that never happen... but its worth a shot maybe it is..

but i can ask around at my school and see if i can get any info for you

It's not the coolant mix cuz you can run straight water and that wont happen.

It's got to be the thermostat. That is the only thing that can cause the engine to over-cool besides an over-sized radiator.

How do you know your engine block isn't getting hot?

Which sensor did you replace? There are multiple CLT sensors and one of them is simply a switch for the rad fan.