amej8

Friday 10/15:
I was driving my car today and noticed the temperature gauge wouldn't go past the the top of the 2 bottom bars. It fluctuated up and down (depending on if I was on the gas or on hills) a few millimeters. I changed the thermostat within the last 30k so I'm ruling that out unless it really went bad that fast (it's only been replaced once since the car was bought new). I'm pretty sure the fan kicks in though I'll check tomorrow. Also, I was driving with the heat on full and blower on. The radiator fluid was drained out of the bottom of the radiator drain plug then refilled roughly 3-5k ago when I did my timing belt. The radiator and fan are still original AFAIK.

Sunday 10/16:
I had bought a new IACV gasket earlier in the week so I took my IACV off, cleaned it out (again), put the new gasket on, put the IACV back on, took my radiator cap off, and started the car and let it warm up until the radiator fan kicked on a couple of times. The gauge went up normal, only a couple of air bubbles came out of the top, I topped off the fluid after turning the car off. So it's normal for now....until next time....

Today Monday 10/17:
Back to not working this morning... I have ~6.2 mile (city) drive to work and usually, the car is fully warmed up by 2 miles and the heat is coming out hot as can be by then as well. The temperature needle was JUST starting to move by the time I got to work and the heat was only mediocre warm. I'm starting to think I need a new thermostat but it's only been approximately 30k miles since I got my last one.

Any input is appreciated. Thanks in advance!

Dioxine

Mileage is really as big of a factor as the brand of thermostat and what kind of fluid you keep in it or water. Sometimes the wax can leak out of the thermostat early causing it to fail prematurely. I would just invest in a new one cause thats really all it could be lol.

amej8

Oops, forgot to provide car details. Car is a 99 ex with 222k miles. I used a Honda OEM thermostat and I used Advanced Auto 50/50. I've never had a problem with it before. I drive my car every day, all year.

motegicivic

Chances are a honda thermo stat is not bad, but you never know. The heater not getting too hot, is making me think it is the thermostat.

How is the temp of the hoses when you squeeze them, I would try that. Note the upper and lower rad hoses.

At least you are not overheating.

Another thing maybe the gauge sending unit is going out, you can test that.

amej8

Where is the sending unit and what is the process for testing? (I'm not good with electrical stuff)

I will check the radiator hose temps and pressure right when I get home from work. I'm assuming they should be hot and hard to squeeze?

And yeah I would much rather have my issue now than an overheating issue. At least I can drive the car lol.

motegicivic

It is easy:

amej8

Thanks! I have to find someone with an ohmmeter now.