Overheating at Idle

[Drew99GT]

If it's not overheating under load while moving, I highly doubt the thermostat is bad.

I bet water pump erosion, as increasing rpms will increase flow and lower the temp.

 

[Mr Nice]

It could be the head gasket is leaking.

 

[cjcride]

Is it idling too slow?

 

[HowAboutThis]

Given revving in place dropped the temp tells me more coolant volume is the issue. Either low on coolant or water pump needs replacing. That's my guess. Could be fan isn't coming on correctly, too. But my gut says the other two.

 

[dlayman]

7th gen Civics are known for head gasket failure, main symptom being random overheats. That doesn't quite sound like what you have though, but a possibility.

 

[HowAboutThis]

Originally Posted By: dlayman
7th gen Civics are known for head gasket failure, main symptom being random overheats. That doesn't quite sound like what you have though, but a possibility.


Yeah, if coolant is low I'd be worried about where it was going...

 

[Quest]

Originally Posted By: dlayman
7th gen Civics are known for head gasket failure, main symptom being random overheats. That doesn't quite sound like what you have though, but a possibility.


That is only true if the owner lets their 7th gen civic engine overheats first.

There's a cause and a consequence. The cause is mostly overheating but most owners or posters won't mention that....

Q.

 

[fenixguy]

Thanks everyone! So far it seems to have been the thermostat. I took it out (turns out it was OEM, not Advance Auto) and ran the car without it until it the gauge got up to halfway. It wouldn't go any higher. Took the t-stat inside and checked it on the stove. It is supposed to open at 78 C but didn't fully open until around 90. I took it out and let the water cool back down to around 80 and it would only barley open. Ran to the Honda dealer and paid an outrageous amount for another one. Tested it in the water first and at 80 it was fully open. Put it in, bled the air, and let it set. Idling in park it won't go above 188.6F (torque app on phone). Put it in D with the park brake on, turned on the headlights and rear defrost (for load) and it would get up to 205 and the fan would come on. Fan would run about 30 seconds and it dropped back to 195. Rinse, repeat for a couple cycles all with the same result. The wife and I drove it to the grocery store and back, about 40 miles round trip up and down lots of hills. I let it idle in the parking lot for a minute or two and it never got above 188.6. I have heat, the fan is working as supposed to, and it's not overheating! I'm going to drive the heck out of it before it starts to snow and make sure all is well.

One note: This is a 6th gen Civic, a 2000 model with the 1.6l. My other Civic is a 7th gen with the 1.7l that is supposed to blow head gaskets.

Have any of you guys heard of a thermostat being slow to open or opening only partially? This was a Honda OEM thermostat with 20,000 miles on it BTW.

 

[StevieC]

Good Stuff

Usually thermostats fail open or closed and not in between but sometimes this can happen it's just not as common.

 

[dlayman]

Originally Posted By: Quest
Originally Posted By: dlayman
7th gen Civics are known for head gasket failure, main symptom being random overheats. That doesn't quite sound like what you have though, but a possibility.


That is only true if the owner lets their 7th gen civic engine overheats first.

There's a cause and a consequence. The cause is mostly overheating but most owners or posters won't mention that....

Q.


I guess it depends on how you define overheating. On my car, I noticed the temp (dummy) gauge going slightly above half way on occasion, never near the red zone, and took it it a good mechanic. He had a very hard time replicating the symptom, but did find a small amount of exhaust gas in the coolant, and was able to diagnose the gasket failure. When he removed the head, the gasket was basically rotted out. It was replaced and no problems in the 30k miles since. I wouldn't define that as an overheating event as it was still within acceptable operating parameters. This generation of Civic is about as bad the bad Subaru generations. There are two types of them, those that have had head gasket failures, and those that will.Fortuantely it's not a terribly expensive fix on the Civic.

Certainly an overheating event would put the head gasket at risk, but not all gasket failures are preceded by overheating.