Rep Power: 191

Actually, my car has been overheating, periodically, since this past winter. I've been kind of crossing my fingers/praying/in denial that my head gasket was likely bad.

Symptoms: Will overheat at random times. Worse seems on a hill, or idle.

Went and used a block tester today, and it stayed blue! (No blue-green, and certainly not yellow, aka the 'bad' indicator). Kept sucking air through as the car heat up, revved the engine a bunch, and kept sucking air through the fluid even when it was over-hot, and no change at all.

So temporarily, I feel the Head Gasket is fine. I suppose unless I let the car overheat badly and it then kills it. Who knows.

(More info: No smoke from exhaust, no coolant appears in the oil (it's not milky).)

The car did overheat after it got to temperature, and what did I notice? The fan didn't kick on! Actually, it did, but only after a prolonged overheating (it wasn't up at the 'H', but it was at the top of the symbol in middle of the gauge). It also kicked back off before cooling down to normal.

Fan relay? (I've previously swapped it with the horn relay, so maybe not that? Or they're both bad?). Also what is under the dash, isn't there a fan relay in the inside fuse box too? Is there a separate sensor for coolant temp besides the one that tells the gauge that it's hot?

I'm also going to order up an OEM honda radiator cap, and throw that on just because.

What could be causing the fan to delay turning on, and kick off prematurely? Coolant temp sensor wonky? Relay? Where are all the relays related to the fan (I'll replace them all)? Something else?

 
Rep Power: 367

look for the fan switch

 
Rep Power: 191

I bit the bullet and went to the dealer, cause I wanted genuine Honda parts for this job (I don't want some garbage part failing prematurely).

I replaced:
- Radiator Fan Switch
- Radiator Fan Relay
- Radiator Cap
- 20A Condenser Fan Fuse (I found out it was blown while checking fuses under the hood. I think it just happened, cause I thought I checked it a few days ago, maybe I missed it last time.)

I also ran out of Type 2 premix, so I'll prob pick up another jug next time I'm near a dealer. I was considering replacing the Thermostat (it's currently an aftermarket Stant Superstat, but I do believe it's opening properly cause both hoses get hot, so that should be fine...but I'll replace that with a Honda part next if there's any issue going forward).

Radiator fan and condenser fans come on, and no overheating in the ~30min of driving since replacing the parts. We'll see what tomorrow brings.

Thanks for the reply!

 
Rep Power: 359

Get a Fail-safe one. That way if it fails it will fail open and not get stuck closed. I have ran that in my Civic and they seem to work fine. They look identical to the Honda one. This way if it overheats, you know it's not the thermostat. Call around, not every parts store has one. Also it's not a bad idea to change the coolant. You may consider having it flushed, if you do, do this before you change the thermostat. Then replace the radiator cap if you haven't already.

Another thing you can do is run the car for a bit with the cap off. Make sure the coolant is circulating through the system. If the coolant isn't circulating you may have a bad water pump, or possibly a plugged heater core.

As always, before opening the radiator cap on a pressurized system make sure the car is cool. Safety first. Coolant flash boiling will blast your skin right off.

 
Rep Power: 191

Water pump was done when timing belt was done, 10k miles or so ago.

Back in the winter after first overheating I did the following:
- Replaced Tstat with Aftermarket (Stant Superstat, OEM Temp), and Gasket.
- Replaced Radiator Cap with Aftermarket (Stant, OEM Pressure).
- Flushed cooling system with distilled water, then Prestone Super Flush (sodium citrate), then more Distilled Water. Then drained and filled it with Honda Type-2.

It actually didn't overheat from then until like a week or two ago, when I was over @ a friends house.

I do believe that the radiator is clean and not plugged (no evidence of any buildup on the tiny part I can see inside radiator) and water ran right through it no prob when draining. Heat does work, and gets toasty hot, so I am not sure that a clogged heater core could be the culprit.

 
Rep Power: 359

Well, hopefully the stealership fixed it and didn't charge you an arm and a leg. Sounds like you did the correct things otherwise with the cooling system.

 
Rep Power: 191

$389 for Timing Belt, Water Pump & Gasket, and Accessory Belts. +$75 for Tensioner. Came to under $500 including tax. Can't beat that for dealer service + OEM parts.

 
Rep Power: 200

No kidding! I spent close to 200 just for parts to do all that myself!
The main thing with me though is that I am a mechanic and know that most guys aren't like myself and don't focus on a job well done, they focus on more jobs per day....
They go for quantity not quality...
They give good mechanics a bad name....
I might not make as much jack at the end of the day, but they won't come back for the same problem either....

 
Rep Power: 191

I think you misunderstood me, and then I misunderstood you. I had to re-read what I wrote before I figured it out.

I went to the dealer for the OEM parts this time (rather than aftermarket parts), but I've done the labor for everything cooling-related myself. The only things I've let the dealer do have been the Timing Belt and two ATF drain and fills. With the exception of those things, I've done everything else myself.

 
Rep Power: 367

Well, the fail-safe sounds interesting.
Around here, there were several cases of aftermarket thermo and caps failing, so these are cheap insurance to get at honda, just for information. You might have gotten lucky on the aftermarket one, though Many did not.

Hope yours will be OK for the time being

 
Rep Power: 359

I also change my coolant, thermostat, and radiator cap like once a year, so that might be why I haven't had issues. They are cheap parts, I don't mind, even if it's overkill. The parts are actually cheaper than the Honda coolant. . haha.