My civic only sees normal operating temp when at idle when i start to move the temp goes down half way in seconds - i just replaced the radiator termostat engine temp sensor and coolant annndd water pump when it does reach normal temp on gauge the fan kicks on this is drivng me crazy any help is greatly appreciated

2000 civic si

 

bump
mine does the same after i propped up my hood.

 

@ idle, fans are suppose to kick in, not when driving though

 

in for the solution

 

hmm that seems like a weird issues, its seems like you have replaced almost every component that would effect the cooling system. If you can't figure it out maybe run the fan on a switch so you can turn it on and off when you like..?

 

highly common bizzness here, my homeboy is an acura mechanic and he has two cars that do it. he tried going to a honda oem thermostat and his acted normal again, but the other one didnt so i guess its like shootin the breeze in hopes to get it right

 

i've seen people with cardboard sticking from the tops of there radiators is that to reduce air flow to keep the car at normal operating temp while driving?

 

^^ That is most likely the reason they are doing that, however, I do not recommend it. I would get a different temperature T-Stat instead.

 

At lunch i am going to hook up the HDS and see what the coolant reads at - I will keep everyone posted because every other thread i have found no one posts any resuslts to know how the car was repaired

 

I also have a similar problem. Well I have a cx racing dual core radiator with new piping and a brand new oem thermostat. I have my fan wired on a custom on/off switch. My temps never get higher than a 1/3 of the way up. Well unless I leave the fan off and let idle fora good half hour. But than as soon as I drive it it goes right back down. Should I buy an aftermarket thermostat that opens at a hotter temp. I'm worried about damaging something.

 

What is the temperature outside ?

Try disconnecting the fans and see if your coolant temp goes down with operation.

( do you have an aftermarket coolant gauge to diagnose exactly the temperature ? ) .

and you replaced the thermostat with an OEM honda correct ? do you know what temp rating you have ( or partnumber you purchased )

 

did you use all oe honda parts?

 

Is the system properly bled?

 

You might be losing some cooling system pressure due to a small radiator leak. Even a small drop in cooling system pressure will cause the car to take much longer to warm up; if it's cool outside and you are driving on the freeway.

 

Cx Racing Dual Core Radiator is brand new. Had it for maybe 2 months before I took my civic off the road for winter. Tubing is all new as well. Cant remember the brand but its blue. haha. No leaks of antifreeze at all coming from anywhere. No white smoke or smoke of any sort so I know none is being burned either. All the gaskets on the head were replaced with about 2 months of DD on them with Falpro Gaskets. The system is also properly bled. Thermostat is OEM Honda and its for the 94 DelSol or 99 Civic Si since I have a B16a. I believe it opens at 160. Was tested in hot water before I installed. Also replaced the water-pump from a 94 DelSol VTEC. I have a switch on the interior that turns the fan on and off. So I know its not an issue that deals with the fan/wiring. I can leave it off driving down the road at any speed and temp. is still at 1/3. If I let it idle for a like 30+ minutes than it will start to overheat and the fan must be turned on. I do not have an aftermarket temperature gauge, hopefully will within the next few months. The outside temp. is anywhere from 70 degrees to 90 degrees. I Live in Michigan and take my Civic off the road for the winter and garage it.

 

My civic also has this weird cool running state. I live in florida so i believe it is even more weird. I turned on the A/C and had like a somewhat hard run and the temp barely raised. I had weird idle/ a little white smoke, but i think it was due to running 6 month+ old gas (it sat for a while). Car has no leaks, and i checked the radiator inlet and outlet hoses, both were pretty hot when i grabbed them. It also stays at 1/3 temp.

 

mine does this too. the thermostat i bought from autozone was rated 170 degrees (according to them thats the supposed operating temp for a 99 civic si) however i was on a racing site looking at thermostats and one said the recommended operating temperature is 190 degrees. so i went on ebay and found a 190 degree thermostat for 9 bucks. i realize this is an old post but maybe this will help someone else with this issue who finds this thread. good luck!