Hi everyone...i'm a newbee in this forum so hopefully you can help me out.
I have a 98 Civic with over 200,000 miles. Last week by the time I got to work I realized that the temp needle was getting high. So this weekend I replaced the thermostat. I drove the car to test with also the AC on to test and it was working fine (mostly freeway driving). But once I got on the city I noticed that once I got to a stop light the needle will start going up until I move again and it would eventually level off. When I got home I left the engine on while on the driveway and the needle was going up again. I popped open the hood and noticed that the fan (in front of the radiator) was not on. I then turned off the engine and waited a minute or so and turned it back on and the fan turned on. Any ideas? Do I still need to disconnect the fan swith and hook it up directly to the battery to check, since it went on already during startup? I assumed that it wasn't overheating in the freeway is because the air was circulating, but when stopped the fan doesn't start up.
Any ideas on what to check? Thanks.

 

The fan relay may be wonky, but you saw it kick on so it likely isn't the motor or fuse. Check your radiator as well, make sure there isn't a coolant leak (look for hard water deposits around fittings and such), or that it is simply out of coolant. Only other suggestion is the head gasket. Mine went out at ~160k, and it's looking like a fairly common problem among 5th and 6th gens. I had the same symptoms as you at the beginning, the engine runs cool enough on the freeway because of the incoming air flow, but the second you stop it gets toasty.

One good test to run is to verify the radiator and overflow tanks are filled before a long drive, and then check it at your destination. Be sure to bring along plenty of water and a rag (and give yourself plenty of time) in case you need to pull off and refill the coolant. If it's low when you get there (or boiling furiously at any point) then you've got a leak.

As you know, running an engine too hot is really a bad idea. Turning the heater on full blast is a very temporary band aid fix to get you to your destination.

 

Flush the coolant system. Drain the Block AND rad. Replenish with prestone. Should be okay. What temp thermostat did you put in? You put the spring towards the motor right? Did u connect all sensors back as they were ?

 

I bought a thermostat from Autozone and installed it. It was easy, just unplug the sensor and two bolts. Yes I replaced the sensor back. Thanks.

 

I guess u no longer need help.

 

Yes I still need some ideas. Yes I installed a new thermostat (as noted on the original messag) but it still overheats when i'm stopped.

 

i would say bad fan relay or temp sensor

 

right, there is a sensor that goes right near the thermo, and its probably bad. replace that and it should fix it. coolant temp sensor BTW.

 

An alternative option would be to wire the fan to a switch in the drivers compartment. This gives you control of the fan say when driving in heavy traffic. It also allows you to turn it off when driving on the highway when not needed. The major downside to this is that you need to monitor the engine temps a lil closer.

 

Thanks for the reply's but it overheated again. okay i checked the thermostat again and there was a slight leak at the bottom of the housing. So I took it apart again and put it back and still a leak. I then took it out and bought another gasket, I then compared how I put the casket around the thermostat to the picture in the manual and it was backwards (note: take a digital picture before pulling out the old thermostat just in case). So I put it back on and no more leaks. The car was fine for a couple of days, no overheating. I would see the temp go up a little but would eventually drop. The check engine light went on again and on the way to work (about 40 miles) today it started to overheat again, almost to the red. I pulled over and waited a couple of minutes and started it up again and the temp was normal.

I remember last night I checked (on a cold engine) and the overflow reservoir was almost full and I had to put more coolant in the radiator.
Could the coolant be burning?
Do you think it could be a blown gasket? If so how much would it cost to fix? Is it one of the dyi things?
Has anyone used ta coolant pressure test? If so can you explain how you did the test.
Thanks.