Hi

I'm having a problem with my 2003 Civic lx, I believe it has the d17a1 engine in it.

The temperature gauge in the car says that the cars temperature is getting towards the red line but the engine fans aren't even kicked on and the car doesn't really seem all that abnormally hot. I bought a digital IR thermometer and it reads around 100 degrees at all spots on the radiator and around 200 to 240 degrees Fahrenheit on the engine side of the thermostat housing. When the car is cool it reads about 200 degrees at the thermostat housing and when the car is hot it reads about 240. The exhaust reads a steady 475 degrees F regardless of what the cars temperature gauge says. The head of the car reads around 175 at all times after warmup.

I replaced the thermostat and I have verified that it is opening, before it opens the air blowing into my car is cold and then it opens and the air gets hot.

I do not know what the normal operating range is for a vehicle? If my car is actually overheating shouldn't it be REALLY hot? It doesn't seem abnormally hot and the fans usually don't kick in for a while and when they do kick on it doesn't seem to have any affect on the gauges reading. The gauge, to me, seems to just do whatever it wants.

When I turn the car off the temprature reading on the cars gauge cluster will drop back down from near red level to 1/2 or 1/4 within 2 to 3 mins. I do not know what the temperature gauge is actually reading or at what scale, but assuming that Hot and Cold are at least 50 degrees Fahrenheit app art from each other Newtons Law of Cooling would not allow for any mater to cool that quickly when it's 70 degrees outside. At least that is my assumption, again I don't know what the sensor is reading or at what scale.

I really need my car (even just for driving to get a new ECT gauge sending unit) can anyone provide me with some feedback on my assumptions and possibly tell me at what temperature the housing should reach before a car will overheat?

Thank you

 

Heater not working is evidence that there is a bubble of air in the cooling system. To purge the air out, start with the engine cold. Car must be parked on a level surface or facing uphill. Set the heater to full hot. Take the radiator cap off and fill completely full. Start engine with the cap off and keep adding coolant as necessary so it stays full.

 

But my heater works fine?

 

I just went through the whole mess w/ a 92 HB w/ a 1.6L upgrade. Did the thermostat, Temp sensor, Temp sending unit and temp relay w/ the same overheat aafter 10-15 mins. of idle. I wnt deeper and replace the water pump as the lower rad hose was not heating up, but the upper hose was HOT!!. I got the coolant flow and the lower hose now gets hot, however still high readings on the IP gauge. After using a laser proximity temp reader, all temps were under 200 except when the rad fan kicks in(About 210). After all these and nearly 6-8 mos. down time, It was the IP gauge!!???? I sat w/ the idling for about 1.5 hours and the engine never boiled over and or show indication on the temp probe hihger than 210, but the gauged is pegged up all the way to the red zone. It does go down a little and then up again. SO rare but the gauge does go BAADD even on the HONDA. I might just wire a separate gauge and have it on the A=pillar or under the dash.

 

Thank you that is very helpful information. I was pretty sure the car wasn't overheating. Since you've also posted that you were around 200 degrees F then that confirms that you're in the same temperature range that I am in and that my car is not actually overheating.

Thank you for your response, if replacing the sending unit doesn't fix things then I'll know it's the gauge which is faulty.

 

You are welcome. I love this forum!!