Why does my car overheat after getting off the freeway

1998 HONDA CIVIC
179,000 MILES
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KICKJON1985
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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??
Jun 25, 2012 at 1:00 AM
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KICKJON1985
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I have bled the system and it is doing the same thing still. I parked it with the nose up hill and ran the car with the radiator cap off till the thermostat opened and saw coolant flowing, and kept refilling till it didn't need it any more.
Jun 25, 2012 at 1:35 AM
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RASMATAZ
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Okay, now you chemical and pressure test it here are some guides to help you.

https://www.2carpros.com/articles/head-gasket-blown-test

and

https://www.2carpros.com/articles/car-is-leaking-coolant

Please let us know

Jun 25, 2012 at 2:15 AM
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KICKJON1985
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What kinda chemical testing? Kw? Ph? I will buy a cap and system pressure test kit tomorrow
Jun 25, 2012 at 2:18 AM
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RASMATAZ
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Its a bloc check-chemical tester that changes from blue to yellow in color if there's combustion leaking into the cooling system
Jun 25, 2012 at 2:43 AM
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KHLOW2008
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Are you getting any coolant losses at radiator and/or recovery tank?
Jun 25, 2012 at 8:42 PM
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KICKJON1985
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Currently no. When the engine heats up it will drop some cause of the engine overheating but not normally.
Jun 25, 2012 at 11:24 PM
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KHLOW2008
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No coolant losses indicates the problem lies with the cooling efficiency rather than anything else. Are the cooling fans working correctly? Is this an automatic or manual transmission?
Jun 26, 2012 at 1:42 PM
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KICKJON1985
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Fan is working. It is an automatic transmission.
Jun 26, 2012 at 2:37 PM
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KHLOW2008
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Does both fans work together? Was any repairs done on them previously?

At highway speed are there any indication of overheating?

Is the replaced radiator OEM, new or used?

Jun 26, 2012 at 2:47 PM
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KICKJON1985
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It ussually does t show signs of over heating at highway speeds. After i get off the highway it will start heating up. Ussually after i get back up to highway speed it cools down, but over the weekend i drove it on the highway, it cooled down after getting back on the freeway but after 5 to 10 miles it warmed up above normal while i was on the freeway.

The radiator is a new one from autozone.
Jun 26, 2012 at 4:00 PM
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KICKJON1985
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The 98 honda civic only has one cooling fan for the radiator. The other fan is for the airconditioner.
Jun 26, 2012 at 4:01 PM
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KHLOW2008
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For automatic transmission, they work together.

Have you rechecked the coolant level in the radiator and recovery tank? Do it with cold engine
Jun 27, 2012 at 1:51 PM
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KICKJON1985
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I did it this morning before i went anywhere. The radiator was full. The recovery was a bit low but i had to go on the freeway a couple days ago and it almost overheated so the radiator was low so it had been sucking it back in the radiator. But the radiator was full this morning.
Jun 27, 2012 at 5:52 PM
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KICKJON1985
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As for the fan issue, the 1.6 litre engine has the radiator and the condensor seporated. The radiator is on the left and the condensor is on the right. The oil cooler is part of the radiator. This being said, the fan conected to the condensor doesnt run while the one for the radiator does. I have attached a picture from the mechanic book i have of the engine i have. #12 in the picture is the radiator and the condensor is on the right of it under the silver bracket.
Image (Click to enlarge)
Attached Media
Jun 27, 2012 at 6:07 PM
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KHLOW2008
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The system we have over here is different. For manual transmission, the radiator would be as you have in your vehicle but for auto transmission, the radiator spans the entire front and the fans works together.

If the radiator is sucking in the coolant from the recovery tank, that could indicate 2 things.
1. There was air in system and and has since self bled. You would need to monitor and see if the overheating occurs again.

2. There is a leak somewhere and it is using up coolant.

Top up the coolant and monitor the situation for another one or 2 times and aleways note the recovery tank level.

When you performed bleeding of the cooling system, did you turn the heater on?
Jun 27, 2012 at 8:36 PM
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KICKJON1985
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I think that the reason for the coolant level being low is cause the engine got close to over heating the last time i got off the freeway and spewed all the coolant out of the recovery tank on the ground by means of over flowing it. Since then i have filled the radiator, and have been filling the recovery tank slowly to completely fill the system. I have not yet had time, or the money to buy the equipment to pressure test or chemical test the coolant system yet either. One would think that it would be something simple as it worked fine before i changed the radiator. The fan seems to run, but i am curious if its working properly all the time? Is there a way to test this? Or just replace the relay and go from there?
Jun 28, 2012 at 2:07 AM
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KICKJON1985
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When i got home today from work i poped the hood and checked to see if the fan was working and it seems to be working as it should. The thermostat would close, the fan will come on, then after the fan shuts off the thermostat opens. I checked this by feeling the pressure and temperature of the upper and lower radiator hoses.
Jun 28, 2012 at 4:44 AM
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KHLOW2008
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Did the engine seem to overheat during this trip?
Is the coolant level correct?
Jun 28, 2012 at 8:31 PM
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KICKJON1985
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No it didnt, but it seems to be the lenght of the trip on the freeway. The coolant level wasnt low before i left work, but this morning, the coolant recovery tank was low. But i ran it with the heater on to see if maybe it did still have a bubble.
Jun 28, 2012 at 9:18 PM
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KHLOW2008
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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.
Jun 28, 2012 at 9:23 PM
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KICKJON1985
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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.
Jun 30, 2012 at 8:15 PM
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KHLOW2008
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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.
Jul 1, 2012 at 8:17 AM
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KICKJON1985
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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?
Jul 1, 2012 at 10:26 PM
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KICKJON1985
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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.
Jul 1, 2012 at 10:28 PM
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KHLOW2008
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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?
Jul 2, 2012 at 2:55 PM
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KICKJON1985
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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.
Jul 2, 2012 at 3:29 PM
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KHLOW2008
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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.
Jul 2, 2012 at 4:56 PM
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KICKJON1985
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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....
Jul 3, 2012 at 3:30 AM
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KHLOW2008
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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?


Jul 3, 2012 at 1:08 PM
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KICKJON1985
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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.
Jul 3, 2012 at 4:14 PM
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KHLOW2008
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Is the radiator new or used? Is it OEM? Was anything done to the cooling fan motor or its wiring?
Jul 3, 2012 at 4:31 PM
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KHLOW2008
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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.
Jul 3, 2012 at 4:33 PM
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KICKJON1985
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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.
Jul 3, 2012 at 5:27 PM
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KICKJON1985
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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.
Jul 3, 2012 at 5:55 PM
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KICKJON1985
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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....
Jul 4, 2012 at 3:08 AM
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KHLOW2008
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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.
Jul 4, 2012 at 4:25 PM
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KICKJON1985
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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.
Jul 4, 2012 at 5:04 PM
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KICKJON1985
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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...
Jul 8, 2012 at 8:42 PM
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KICKJON1985
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When i replaced the thermostat a while ago i did put a fail safe one in..... Maybe that?
Jul 8, 2012 at 8:44 PM
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KHLOW2008
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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.

Jul 8, 2012 at 8:48 PM