Mechanics

WHY DOES MY CAR OVER HEAT AFTER GETTING OFF THE FREEWAY

1998 Honda Civic • 179,000 miles

Recently, about a month ago I replaced the radiator in my civic because the radiator had a hole that had started to spew coolant. Other than the leak of coolant the system worked fine no problems with overheating at all. After replacing the radiator the system started heating up (not overheating completely but close once), but only when getting off the freeway. I have replaced the radiator cap, the upper and lower hoses, the thermostat, the clamps on the upper and lower hoses from jesus christ clamps to regular kind, and still heating up. Now during normal in city driving it doesnt heat up like that at all only after being at high rpms. Someone told me a blow head gasket but I have never overheated the car and and it worked fine before I replaced the radiator(of course for the leak). Any ideas?
AD
Avatar
Kickjon1985
June 25, 2012.



Seems there could still be some air trapped in the heater system and as overheating did not occur, you would need to monitor the situation further.

KHLow2008
Jun 28, 2012.
Today as I ran the car on a trip on the freeway to test if it would overheat (and it did start to heat up past its normal operating temperature), I got back to my house and while sitting in the driveway and starting to heat up well past its normal operating temperature I opened the hood to observe it while it was warming up I noticed that the fan was not running. Isnt this something that should be running while its warming up like this to try and cool the water down? And of course the engine had overfilled the overflow.

Tiny
Kickjon1985
Jun 30, 2012.
That could mean the fan switch is not working within range or there is a fault somewhere and the fans are not turned on.

After engine cools donw, recheck the coolant level.

KHLow2008
Jul 1, 2012.
Replaced the fan switch today and the relay. Fan working now like its suppose to but obviously only part of the problem. After taking a drive to test the cooling fans, the fans worked good and the car did not heat up as fast but never the less it did heat up again. Again at freeway speeds the car is cool and doesnt heat up. Or if I havent driven on the freeway and just drive it around town the car doesnt heat either. I am boggled and have no idea. Im starting to think that the brand new radiator that I installed which after installing it this all started might be bad. Only things left to replace on the cooling system would be the water pump. Again, any ideas?

Tiny
Kickjon1985
Jul 1, 2012.
I did notice that when I stopped to get the relay that the recovery tank was almost full already, and I only drove about 5 miles or so to the auto parts store.

Tiny
Kickjon1985
Jul 1, 2012.
When recovery tank was almost full, were the fans working then?
How about the temperature readibng?
You mentioned replacing the radiator cap, what rating did you use and did you check if the cap is the correct fit?
AD

KHLow2008
Jul 2, 2012.
The fan was working. The temperature reading said that it was at its normal reading. The cap was new, and came with the brand new radiator, so I assume that its the correct fit.

Tiny
Kickjon1985
Jul 2, 2012.
Normal temperature reading with fans working seems to indiate everything is in order. Did the fans stop after working for a while or does it continue to run without stopping at all?

Check the radiator cap pressure rating. It should be marked 1.1 at or 108. Check the seals and radiator neck. Ensure it is welll finished and does not have any impurities protruding allowing pressure leak.

KHLow2008
Jul 2, 2012.
Changed cap today cause I do not have the means to pressure test the cap, and drove it to test it. It did heat up again today and when I got home I decided to let it idle and observe it. It first would heat up about 3/4 the way to the H, then the fan would come on and cool it down to normal operating temperature, and do this a couple times. Then it heated up to about about 3/4 the way to H and the fan came on and wouldnt bring it back down, so I decided to rev the engine to about 2000 rpm's and to my surprise the engine cooled down when I did this. Does this sound like a water pump issue? I still dont know why it runs fine while I drive in the city or while at low RPM's, but will heat up after being at high RPM's for about 10 to 12 miles.

Tiny
Kickjon1985
Jul 3, 2012.
If you do not have air trapped in system, it indicates poor cooling efficiency. It could be a weak water pump or somewhere there is a restriction in coolant flow. It could also be due to a thermostat that is sticking intermittently. Was the thermostat an OEM unit?

KHLow2008
Jul 3, 2012.
Page 3 of 8

AD