Hello there honda tech

Here's a question for you guys. My car cools down when I'm idling, say at a stop light, but heats back up to normal operating temp when I'm driving, my question is why?

It's winter time here so I'm thinking that just may be too cold outside

I drive a 2000 Civic EX with a 160k on the clock

 

Post the temp gauge readings.

 

Could also be a fan that's always on?
That doesn't help in this lovely cold weather..

 

x2 on checking the fan. maybe a short?

I have the polar opposite problem. Heat up when still, cold when driving.

 

Don't have the readings, I guess I'll stop by advance auto and rent an obd 2 reader which I think gives me a temp reading. I'll try to listen to the fan next time since I always have the radio on.

 

This is great^ but more precise than I was looking for. I just meant where does the needle sit when you call it normal versus cool, as approximations?

 

When I say normal temp the needle is in the middle where it should be lined up with the watery line on the temp symbol. Depends on how long I idle but it can reach down to about a centimeter, sometimes if its really cold outside the car won't fully warm up

 

Have you replaced the thermostat? That's the first place to start in my opinion.

 

I haven't replaced it ever since I got the car at 122k, I was thinking the same thing as well but wanted to make sure before replacing it.

 

It's a basic maintenance item - should only cost about $20 for the OEM one. Bleed the cooling system after installation.

As mentioned by others, it's also not a bad idea to check whether the radiator fan runs all of the time - it shouldn't especially in cold weather. When the engine is cold, turn the key from off to ON(II). If a previous owner jumped/shorted the fan switch connector, the fan will run (but shouldn't).

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Bleeding the cooling system may take 20-30 minutes.

1) Park the car on an inclined driveway with the front end higher than the rear.

2) Push/turn the dash heater lever/**** to MAX heat. Fan need not be on.

3) Follow the directions in the diagram below




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Yours is doing exactly what one of my CRVs was doing around Christmas. And as suggested earlier it was thermostat stock partially open.

When bleeding I use one of these


It comes with radiator adapters, you put it on and it holds extra coolant. As the engine warms the air comes out and is replaced by coolant. When done. You insert the funnel plug and remove it with no mess.

 

Almost guaranteed to be a thermostat stuck partially open. For some reason many of my late 90's integras and civics had this problem. If I had to guess I would say that Honda changed its thermostat supplier in the mid 90's as I never had that issues with any car older than a '96.

 

Yup!! This exact same thing happened to my sisters Accord. Definitely the thermostat. RonJ@HT lined it out nicely for ya. Should take care of it.

 

Thank You all, and thank you Ron for the Info. The car has been doing it more now since i posted this thread, I will be taking a trip to Honda to pick up the Thermostat part. I'll let you guys know how it turns out

 

Well guys, I finally replaced the Thermostat today in this cold *** weather. It was definitely worth it, looks like the original thermostat was still there. when i took it out it had pieces that were shredded. so everything is back to normal, it warms up and i got heat. thanks everyone