Engine Overheating Mystery?

Question

Car: 2000 Honda Civic EX, 1.6L 127 hp I4, 4-Speed Automatic Overdrive,

Problem: My engine is overheating. Whenever I drive in stop-and-go traffic for 30-45+ minutes my car starts to overheat -- in cold weather, hot weather, with the air conditioner on or off, with the air vent on or off (although, I’ve noticed that driving with the air vents on the blue/cool setting will make the car overheat faster than if I dive with the ac on).

Additional Info:
The temperature gauge will almost immediately return to near-normal levels upon turning my heater on. The car doesn't overheat with freeway driving.

My timing belt was just replaced. I have no blockages in the hoses. The hoses are new. The thermostat was also just replaced. The radiator has been flushed. The coolant mixture is balanced to the correct levels and does not fluctuate when my car overheats. My oil levels do fluctuate, however: when my car overheats, the oil levels drop. I don’t have an oil leak, nor is their any sign of water mixing with my oil (i.e. a murky gray film or color on the underside of the oil filler cap) nor does my car begin to smoke or let off steam when it overheats.

The fan seems to be working (when idling, the car will heat up, but the fan will turn on when the temp gauge climbs about to the mid point -- cooling the engine back to the normal temp. However, when I drive in stop/go traffic, the temp gauge climbs to the highest point, and will only drop once I turn on the heater on full blast), but my mechanic still thinks that my fan switch may be the problem. I just had the 100k tune-up.

Knowing absolutely nothing about cars, I asked my mechanic about the possibility of a blown, cracked, or otherwise damaged head gasket (which seems to be the consensus diagnoses in other forums dealing with similar issues) -- he scoffed and said that wasn't the problem. Hopefully, he’s right. That would be a huge kick in the pants.

Anyone have any idea why my car is overheating?

Thanks.

Answer 1

Most likely they replaced your thermostat with a bad thermostat. Let someone else have a look at the thermostat. Running your heater wide open will help keep a car from overheating. You mentioned oil levels do you mean oil pressure? Have that checked too but most likely it is the thermostat. Another problem could be in the transmission, get it inspected.

Answer 2

When they pressure tested the system did they also do the cap ?If not then replace the cap their a few bucks , you get a higher boiling point when the system is under pressure,it could be the cap is getting weak and opening prematurly causing it not to be underpressure and the coolant boiling over.As far as the waterpump just feel around the hoses making sure they have constant pressure once the car is running.if you have contant pressure all around then the waterpump should be operating fine.And changing the thermostat agian wouldnt be a bad deal their like $10 if that , i know some like at autozone are made cheaply where it wouldnt be uncommon for it to be defective.Other than that just make sure you have your 50/50 mixture of antifreeze and distilled water.And with all the work was it done at a shop or yourself,one other thing i would do is make sure the air is bleed out of the system,on your thermostat housing you should have a bleeder screw,while running the engine uncap that untill antifreeze comes out and then close it up, with air you can get hot spots.Hope this helps you.

Answer 3

Sounds like maybe your thermostat is sticking.

one easy way to find out is just take it out for a day or two and see if you over heat. they are normally easy to get to and remove/replace.

you wont have heat when you do this, since the engines coolant will be constantly cycling not allowing heat to build.

If you still over heat then keep an eye on your oil, really black or smelling slightly burnt. In which case try an oil change including the oil filter. The oil not flowing well can lead to alot of heat build up as well.



if it was any gasket, your parking area would be covered in oil, or fluid, and you would over heat a lot faster like within 5/10 minutes



good luck.

Answer 4

It does sound like the fan to me or dirt debris whatever blocking air flow through the radiator! most likely not your thermostat or head gasket tho you can check your oil for white cream or your exhaust for a white color that will tell you if its your head

Answer 5

i would be willing to bet that the fans are not working when they should or you have a blockage in the cooling fins. you will also find two different temp sensors, one for the gauge and one for the computer. i think the one for the computer might be failing of disconnected for some reason.

Answer 6

You can check to see if you have oil in your coolant, or coolant in your oil. This would be a good indicator if your head gasket is leaking. If you don't find anything, it doesn't mean it isn't happening, it's just a quick thing to check out that may reveal something.

Answer 7

Weird but I had to unplug my my fans they would turn.on to fast which cooled the right side down where the thermostat was so it would not open. After that I was able to bleed all air and reconnect everything worked fine for awhile till I jad to do process all over. Dominino affect high temps caused black burnt oil had to changed that to beat to have taken to shop

Answer 8

COULD BE SEVERAL THINGS,, 1. DIRTY RADIATOR CORE, 2.BAD RADIATOR ELECTRIC MOTOR FAN, OR TEMPERATURE RADIATOR FAN RELAY, IF YOUR CAR HAS ONE, 3. BAD FAN CLUTCH,,, IF YOUR CAR HAS ONE., YOU CAN CHECK IF YOU HAVE A DIRTY RADIATOR BY TOUCHING THE RADIATOR WITH YOUR HAND AFTER YOU RUN IT FOR A FEW BLOCKS,, CAREFULLY TRY TO FEEL THE RADIATOR FINS,,,, IT SHOULD BE HOT 100 o/o OF THE FINS ON RADIATOR,,, ANY COLD SPOT IS WHAT IS DIRTY AND NOT COOLING PROPERLY.... JUST BE VERY CAREFUL WHEN TOUCHING RADIATOR,,,,, GO SLOWLY SO YOU WON'T BURN YOUR HAND

Answer 9

have the head gasket replaced anyways if you havent yet since you have 100k. Its cheap and on most vehicles relitively easy. (although they usually show small oil leaks first) Your either buring oil or losing it, so you got to find out where its goin.

Answer 10

I would go to a different mechanic sounds like a head gasket to me

Answer 11

sounds like your water pump may be 'going south' ..not enough fluid exchange for cooling