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?
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Kickjon1985
June 25, 2012.



If there is a coolant flow restriction, then im gonna assume its in the radiator cause the system was fine before I replaced it(no overheating at all and no movement of the temp needle at all.). The order I changed things was: radiator cause of leak, also changed upper and lower radiator hoses.

Thermostat a week later cause it had started overheating like I said. It wasnt oem cause I purchased the fail safe thermostat to prevent it from failing closed.

Then over this last weekend (which was about 2 weeks after the thermostat) I replaced the fan relay and cooling fan switch that sits in the thermostat housing.

Tiny
Kickjon1985
Jul 3, 2012.
Is the radiator new or used? Is it OEM? Was anything done to the cooling fan motor or its wiring?

KHLow2008
Jul 3, 2012.
I forgot this. If the radiator is the cause, the temperature reading would most probably increase the faster you drive, unless you are not driving very fast.

KHLow2008
Jul 3, 2012.
I am not sure if it is oem or not to tell u the truth. It was the only one that the auto parts store carries. It was $80. I scheduled a chem flush and pressure test for thursday to tess the pressure of the system and to see if maybe the added flow of the new radiator may have broke some deposits loose or not.

Tiny
Kickjon1985
Jul 3, 2012.
No nothing was done to the fan or its wiring. It was disconnected while the radiator was changed but nothing else. I changed the ect switch and the relay.

Tiny
Kickjon1985
Jul 3, 2012.
Today before I left work I checked my coolant level ( which was fine) I noticed that I could squeeze the radiator hoses and cause coolant to flow into the overflow tank. So when I got home I decided to see how much pressure would be in the system by pulling the radiator cap and to my suprise I was able to pull the cap without it spewing everywhere! I am going to try the old cap that came with the radiator to see if the same thing can happen. But I do know that is mot suppose to be able to be done. If the original cap can do the same thing, does it sound like the neck to the radiator is bad? Obviously if the neck is bad then the radiator is.

Tiny
Kickjon1985
Jul 4, 2012.
Coolant flowing back to the recovery tank while squeezing the hoses indicates the radiator cap is not maintaining pressure. It could be the radiator neck or you have the wrong radiator cap. There are 2 different types of radiator cap and they differ in height and design.

Measure the depth of the radiator neck and compare it to the height of the cap. Cap should be minimally higher.

At radiator neck, check for flushness of the seats for the inner radiator cap seal.

KHLow2008
Jul 4, 2012.
Its interesting, cause I kept the old radiator cap that came with the radiator and when I discovered this I tryed that cap on it again and it didnt do the same thing. All the caps at the auto parts store are exactly the same, only difference is that one is a pressure release and the other is not.

Tiny
Kickjon1985
Jul 4, 2012.
Ok I had my system pressure tested and that was fine but a honda mechanic said that hes seen that before and it was the water pump. So I had the water pump replaced and all the timing components. It seems to have fixed the problem, but there is still a small fluctuation in the temperature gauge. Its only a small amount, maybe an sixteenth of an inch or so, so far. Does this sound normal? Its never moved like that before, that I can remember.

Tiny
Kickjon1985
Jul 8, 2012.
When I replaced the thermostat a while ago I did put a fail safe one in. Maybe that?

Tiny
Kickjon1985
Jul 8, 2012.
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