I own a 2009 Honda Civic that just reached 80,000 miles this past week. Back in June I had a cracked radiator replaced and things seem to be working fine since then but I still notice fluctuations with the engine temperature. When I'm driving the temperature maintains at about just below halfway between hot and cold which is normal. However, if I'm stopped in traffic or idling the temperate will often slowly rise to about 3/4 of the way to the top of the meter. Then, when I start driving again or turn on the heat to drive down the temperature it cools down.

My concern is that there still may be some deeper issue with the radiator being properly installed or other damage. I'm just fearing that one day I'll be stuck in traffic with my engine temperature driving up and up and then I'll have to shut down in the middle of the highway.

Does anybody know if these types of fluctuations are normal or what service might be required to fix this? I've also checked the fans and both are working properly.

 

On my 1988 Civic there are THREE temperature sensors...

One to the ECU (computer)
One to the dashboard temperature gauge.
One that turns on the radiator fans; like when stuck in traffic.

If you turn your AC on full blast, this should force the radiator fans on too.


With car parked, engine running, hood open...
Turn on the AC and verify your radiator fans are working.

Then you might want to check the radiator fan switch/sensor.
On mine, I found one wire was disconnected. It was located on the back of the engine block, below the intake manifold, near the alternator. Next to it by a few inches was the oil pressure sending unit/switch.

Verify where yours are and check to make sure they are working properly.