Engine Cooling problem
2002 Honda Civic 4 cyl Two Wheel Drive Automatic 85000 miles
My engine keeps overheating while I'm driving slow, stopping on stop lights, in traffic, etc. When I start driving again, it starts falling. When I accelerate really fast, for example, to pass a vehicle, the temperature shoots up almost immediately. When I'm on the highway, everything is fine. I have changed the thermostat and the antifreeze and coolant is at the level it should be. Any suggestions of what could be the cause for this?
Overheating during slow driving can be caused by the cooling fans not operating or are weak but you mentioned hard acceleration will cause the reading to shoot up, I think it could be due to air trapped in the cooling system.
You said coolant level is ok is it the reserve tank? What about the radiator? Is it full when cold?
May, 25, 2008 AT 9:48 PM
The reserve tank level is always normal, but the radiator fluid level is not visible when it is cold. Today when I used the a/c and it started overheating, it stopped blowing cold air and was blowing warm instead. When accelerated, everything went back to normal. Also, radiator has been changed recently. Should I do a flush to the radiator?
May, 26, 2008 AT 8:46 AM
When the engine overheats, the AC would stop operating.
Since you just changed the radiator, there is no need to flush it. Most probably the system was not bled to remove air pockets.
Since the radiator fluid is not visible, then you need to top it up and run the engine for a short while without the radiator cap to bleed the air out of the system. Keep topping up when the level drops until the the level stop dropping. If you keep the engine running more than 5 mins, turn on the Ac to get the fans working so as not to allow the coolant to heat up to much which might splurge out.
Replace radiator cap and it should be ok.
After bleeding the system keep monitoring for a few days, fluid should be visible when cold. Top if necessary because there might still be minimal air trapped.
Now for the bad news part.
If overheating still occurs and fluid level drops in the radiator but not the reserve tank, then you might have a blown gasket.
June, 9, 2008 AT 11:39 PM
I went ahead and ran the car without the radiator cap, filled the levels to full and replaced the motor to a fan that sometimes was acting up, and it still is overheating only when the heat is turned up. The AC works perfectely now. What's weird is that when I turn the heat on, I don't get any warm air. Not sure what is going on. I appreciate your replies, thank you.
June, 10, 2008 AT 9:34 AM
If no heated air, check the following
1. Clogged heater hoses.
2. Clogged heater valve.
3. Faulty air mix door.
4. Air mix control cable adjustment.
I believe you need to check the coolant level again when cold. You might have a leakage in the heater core.
October, 4, 2011 AT 11:31 PM
I know this thread is old but I like to share this with everyone hoping to help someone else. My sister have a civic xe 2002 engine overheat problem. She had someone else replaced thermostat, upper & lower hose and still overheat. Here's what I did to solve the problem. I replaced the Fan Thermo switch cuz fan not come on, replaced new radiator cap (some overheating problem had been linked to bad cap), replaced radiator reservoir hose cuz cracked, and do radiator flush it solve her overheat problem.