2003 Honda Civic Mysteriously Overheating


#1

This has been happening intermittently for a little over a year now. When sitting in traffic, my car begins to overheat.

I’ve had two different mechanics look at it - the first swapped out the radiator cap.

The second said my coolant levels were low, but he pressure tested the system and found no leaks. He recommended I check my levels before taking long trips - so this weekend, before driving 380 miles to Phoenix, I checked my levels. They were a bit low, so I topped everything off with coolant and everything was fine on the drive out.

On the drive home, however, stuck in traffic, the car began to overheat. I pulled over and checked the reservoir and it was mostly full of coolant, but I added a little more, let it sit for a while, and then made my way through the traffic and home.

Also, I tested the fan, and it comes on.

Thoughts on what this might be?


#2

Are you losing fluid? The car has 2 fans if you have AC? Do both run?


#3

I’m losing fluid very very slowly. For instance, I was low in August of last year, I topped it off and then had a problem again in April.

I think both fans work - the AC works fine and the fan in front of the radiator comes on.


#4

When you turn on the AC does the second radiator fan come on?


#5

I’m not sure - how can I tell? Where am I looking?


#6

Radiator should have 2 fans that are driven by 2 relays. One fan is driven by the engine temp sensor the other comes on when the AC is turned on.


#7

so you lost a little coolant in, what, 8 months? and you drive , in traffic, in phoenix and other hot areas?

if that s correct, your radiator cap may have just released some fluid here and there, while it was hot and you were in traffic, eventually getting so low that it overheated


#8

@knfenimore - where can I find that second fan? The AC one works.

@wesw - I’ve already had the radiator cap replaced… could this one be bad too? Also, I topped it off back in June - had the mechanic look at it and replenish everything - and the car just overheated, so this time, it was only 3 months between problems. And really, it shouldn’t be happening, right?


#9

Assuming the mechanics weren’t total morons, they must have tested the fans. Sadly, these long-term intermittent overheating problems many times lead to a head gasket failing.


#10

Does the fan come on with the AC off and the engine warm? If your losing fluid they need to test the antifreeze for exhaust gasses and or do a leak down test.


#11

Wow seriously you should read my thread/post…we have the same car and SIMILAR problems. I even thought this was my thread by the title when I saw it. Anyways, since your car overheats at idle that can sometimes mean a few things such as a bad thermostat that can’t regulate temperatures right, a bad fan/fan switch would kind of make sense since you car was fine before it was idle or a…“GULP”…blown head-gasket. Hopefully it’s not that because that is pricey and that looks to be what i’ll have to get soon. Btw if you research online about overheating hondas 2003 like mine and yours you’ll find a common theme with the head-gaskets…idk if it’s some sort of defect, bad manufacturing problem or maybe even poor engineering but they seem to blown constantly…


#12

“Does the fan come on with the AC off and the engine warm?”

This is key. If the temp sensor on the radiator is bad the fans will still come on with the AC.


#13

So, reading about possible headgasket being blown… one of the indicators said the oil will be almost like coffee and cream - my oil is still a light amber… I know I need to get it to my mechanic ASAP, but is this a good indicator that it’s not the headgasket?


#14

Not always the case. If it the breach is to the piston, the fluid will be burned away and gasses will enter the antifreeze. The antifreeze can be tested for exhaust gasses.


#15

Okay. I did just check my coolant and I had to add about a quarter of a gallon after having filled it up before my AZ road trip on Friday. If it’s not a headgasket any thoughts about what else it could be?


#16

If not head it’s a leak. You can put in die to see it with a blacklight. Water pump could be leaking.


#17

Yeah, I just took it to a mechanic, he tested for busted head gasket and he’s fairly certain that’s not what it is… so on to the water pump, I guess.