Very long but detailed, please help. I have searched many threads here, but am still confused with my problem. I just paid my 2005 civic off 3 months early and whaaam it starts to over heat periodically! I am original owner, and take immaculate care of my 2005 Civic EX Special Edition. New water pump, timing belt, all belts fluids changed at 100K, oil every 5K religiously, tires rotated, etc, etc. This past December here in Michigan my problem started. I was driving on back road doing 55mph or so to notice my temp needle going up, wtf? Pull over buy antifreeze, take off rad cap, kaboom antifreeze everywhere, top it off, drive, no problems for 3-4 weeks, doing 75-80 on eway, notice needle going up, pull over top off, etc etc. At times I can drive 100-150miles or more NO problems and then bam over heat. Ive never let the needle get to the red, but it has gotten dam close. So My buddy ASE mechanic at Belle tire, pressure tests it, does hydro carbon test, all seems good. My AC condensor fins shot to hell, he says Tom, the only thing I can think of is not enough air flow. He had car running for 2 hours in shop, fans NEVER kicked on, but he said it never started to overheat. Change that for $160 DIY go bout 2-3 weeks and bam start to overheat. So I then go to honda, and they say they are stumped? I buy a t stat and new rad cap, go 2-3 weeks, whatta ya know start to over heat. Then I decide to change my radiator, Im at almost 150K so its up there, go a few weeks, and same crap. My other buddy asks if fans are kicking on, ???? I leave car run, they never kick on, i take out relay andair blow the terminal in fuse box under hood out put it back in, fans kick right on!?? Go couple weeks drive 85 miles no probs, I open hood and overflow bout an inch or so from top i pop rad cap, couple hours later I leave for my 80 mile trip home and at bout 65 miles into it needle starts to rise! Gets to 3/4 and goes back to normal just under half, did this 2-3 times, then rest of 75mph ride fine. Pull in drive leave it run for a min gets to 3/4 again, fans not running at 3/4, so I turn off. this time I DONT pop off rad cap to see if overflow that again is 1-2 inches from top will go back into rad. This morning it was just above max, so it did flow back to rad. Let it run on incline for 45 mins and was able to put 10-12 more ounces antifreeze in. Never got hot but fans never kicked on. I went to autozone, took fan relay in, they said they couldnt test it, and was $42 to replace, I didnt buy it, put it back in came home let it run some more and fans were cycling now! ?? WTF please help, relay cooling sending switch, maybe headgasket, Please help. Thanks,

Tom

 

My fans are not kicking on either. They only come on when the A/C is on. Does yours do that? I am replacing the water temperature sensor on the thermostat (40 bucks at Honda dealership) and see if that fixes the problem. I've already replaced the thermostat itself, checked the relays, replaced the coolant, and I am pretty sure its not a headgasket because there isn't any white smoke, misfire, or water in oil. I don't think its the radiator or the cap. You might want to consider replacing it as well.

 

im having the sam problem.. i have a 2004 honda civic ex. its over 100k. it barely started over heating so i changed the coolant. still is overheating. should my next step be the water pump?? answer asap please.

 

Let me know how the sensor does, I have changed everything but that sensor and relay, and my fans do at times come on. Ive got $400+ in repairs already plus the $1200 maintenance to honda last fall for the water pump and all belts changeout, with all new fluids. Dam this sucks!

Tom

 

My fans do NOT come on when the ac is turned on, but I even replaced the AC condensor, and have NOT yet had the system vaccumed and recharged yet. Will the fans come on if the AC system is not charged at all? Thanks,

Tom

 

Anyone have any info? Without ac system charged should my fans still come on?

Tom

 

im having the same problem too as well i gotta 02 Ex. i just had to buy a thermostat yesterday. but i just currently put in sum coolant for it. i was told that if ur car isnt leaking and ur hoses are fine than its either the thermostat or its the sensor.

 

same problem here with 95 del sol-already replaced water pump,thermostat and temp sensor fan sending unit-relay clicks which supposedly means its fine
told it may be a fuse but neither of my fuse boxes are marked as to what goes to what