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 the fluctuation is gradual and not too obvious, that is normal but not too much movement.

When the water pump was removed, did you check if the impellers were worn or loose? They do occur randomly.

KHLow2008
Jul 8, 2012.
The mechanic said the original was loose a bit. But not horribly. I drove it today to see if it would warm up, bu the whole drive it was good till I got home when I went up a little bit then the fan came on and it went down and stayed down. Its just never moved before all this started so its wierd to me.

Tiny
Kickjon1985
Jul 8, 2012.
When engine cools down. REmove the radiator cap and recheck the coolant level. There is a possibility air is still present system and bleeding is not complete.

Top up if necessary and run engine for a few minutes without the radiator cap and topping as required. You might need to repeat the process a few times.

KHLow2008
Jul 9, 2012.
I will do that. I checked the coolant before I went to work today and found that the overflow was about 3/4 full and the radiator was low. The exact amount that the radiator was low was in the overflow. Boggling that the radiator did not suck the coolant back into the radiator.

Tiny
Kickjon1985
Jul 9, 2012.
This indicates 3 possible scenarios.

1. Bad radiator cap or it is leaking at the neck.
2. Too much air trapped in system.
3. The head gasket has failed.

KHLow2008
Jul 10, 2012.
Well I have changed the thermostat to an OEM thermostat just to make sure that the autozone one I put in wasnt a piece of junk, and still the same thing still. I purchased a block-tester to chem test the system and it should arrive tuesday, so I will conduct this and get back to u to let u know of the findings.

Tiny
Kickjon1985
Jul 14, 2012.
Today I completed the block test and that is negative. The system is sucking the fluid back into the radiator as normal, but I still have a slight warming problem. Fans ar working, radiator new, thermostat new and oem, water pump new, have good coolant flow and about a 60-70% anti-freeze mixture. Radiator cap is good and the mechanic shop said pressure test was good. Any other ideas?

Tiny
Kickjon1985
Jul 17, 2012.
Another question. Is the coolant resevoir suppose to be under any pressure? Even I its not I wonder if it might be bad as when I get out of my car I can smell coolant, but I dont have any leaks, so I assume that the smell is being pushed past the resevoir cap gasket from the pressure and coolant being released into it from the radiator. Any thoughts?

Tiny
Kickjon1985
Jul 17, 2012.
No, recovery tank should not be under any pressure as there is a breather at the cap.

You did not tell me the radiator cap rating when I asked previously.

You mentioned slight warming, how high did the gauge show? Maybe you are paranoid after so much time figuring this out? Lol.

The coolant being sucked back indicates the head gaskets should be good.

KHLow2008
Jul 17, 2012.
Oh its a 1.1 cap. The guage sits about 1/3 the way up from the cold, but after a drive in the freeway and the car comes to a stop for a minute (like sitting at a stop light) it will rise to about halfway up. This is odd to me because before I started working on i, t it never moved at all. Maybe it is paranoia. Any ideas why I can smell coolant so much from outside my car? I had a coworker walk past my car the other day after the car was off for about a half hour and told me he smell antifreeze. And I can smell it pretty good too when exiting the car.

Tiny
Kickjon1985
Jul 17, 2012.
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