WranglerBowman

Ok, I'm pulling my hair out with this one. My wife has a 97 honda accord and it began overheating after driving home from work and she got into stopped traffic. I have checked the coolant and the level was fine, I replaced the thermostat as that's pretty simple, I have replaced the thermoswitch as I thought that was the likely culprit as to why the fans wouldn't kick on, but that wasn't it. I've shorted the thermoswitch plug and the fans both come on but the old and the new thermoswitch won't kick the fans on when the car is hot. The car overheats when driving at highway speed and then coming to a stop, but if I give it gas the temp starts to go down as the water pump increases flow, I'm assuming. I have checked all the relays and fuses under the hood and they are all functioning properly. I shorted the ECT plug and nothing happens but I'm not sure if anything is supposed to happen from that plug, I would think so though. When I turn the AC on the AC fan runs. I have bled the system twice and that hasn't done anything. Anyone have any idea what may be hindering the fans from coming on even as the car starts to overheat? Any ideas or help would be great!

bdmlilburn

check the fuses. i believe there is also a relay that could have gone bad

also bleeding the coolant can be a pita on these cars. you got to let them run with the radiator cap off.

WranglerBowman

Already checked all the fuses and relays underhood and they are all working. I'm getting power to the thermostat temp sensor, cause when I put a paper clip in the thermo temp sensor both fans come on. I've already replaced that switch and that didn't fix it. I've also bled the cooling system twice by topping off the radiator, bleeding with cap off and then adding more coolent.

bdmlilburn

definitely sounds electrical...which is definitely not a strong area for me. if jumping the switch turns the fan on but they wont turn on without jumping it then the switch has to be bad.

Lost Again

First, 4 or 6 cyl?

AC on and only one runs but if you jump thermo "a" BOTH run?

As another member has stated and called me "slow" before, I'm only asking these questions to get a better understanding of the issue......I'm reading the wiring diagram of the fan operation and your description is confusing. If you are getting ground from thermo a and BOTH run but if the ground from the AC control is only letting one run???????

How did you bleed the coolant system?

WranglerBowman

It's a 4 cylinder. When I turn the AC on when I first start the car only the one fan runs. When the car was starting to overheat was when I jumped switch "A" and both fans came on and the engine started to cool down. I have replaced both thermo switch A and B. I bleed the coolant by keeping the radiator cap off and letting the car warm up. Then putting a 12mm on the bleeder valve and letting coolant out, then closing the bleeder, topping off the coolant and then putting the radiator cap back on. Double checked all the fuses and relays. Can figure this out. The car won't overheat unless i'm driving at highway speed and then stop for a few minutes.

WranglerBowman

Thanks for the diagram. I wonder if the fan control module is acting up or something.

Roader

Heat valve on full hot? Be sure to include the heater core when bleeding.

Typical low-coolant symptom. Does the car lose coolant, either from the radiator or from the overflow tank? Does the overflow tank overfill after driving on the highway?

WranglerBowman

I have the heat on every time I've bled the system. Heat valve on full hot? The car is at operating temperature when I've bled. The only time the overfill tank fills with coolant is if I let the car get really hot, into the red on the temp gauge, I try not to do that but it will fill if the car is sitting for longer then 5 mins after being at highway speed. The fans won't automatically come on, that is the entire problem, and it's gotta be something in the electrical system but I'm running out of things to check. If I just drive around with fan plug shorted I'll never have a problem...till the fan motors burn up!

Roader

Mine did the same thing. Weird fan turn on/turn off too. The head gasket was going bad. You may want to do a leakdown test to see if pressurizing the cylinders causes coolant to push out of the radiator fill. With the new head gasket, the coolant level never changes either in the radiator or overflow tank, the temp gauge never gets close to the 1/2 mark, and the fans turn on and off normally.

jdmcertified909

agreed 110% thats a sign of a blown head gasket fans not turning on. and another its not your fan control module becuz then they wouldnt turn on when you jump them. are you bleeding the cooling system with car on or off? oh and another thing. it could also be a clogged radiator

WranglerBowman

Roader...I've been trying to avoid thinking about the head gasket going because I would think the fans would have been running non stop to try and cool a blown head gasket engine, but you say that's what happened to your Accord?
jdmcertified909...I've been bleeding the coolant system with the engine on, a couple minutes after I start it, so the system has some pressure in it, but not enough heat to open the thermostat.

The fans came on saturday for no apparent reason and worked all weekend, then monday the car overheated once I got to work. I keep checking the exhaust to see if it's putting out steam, and I havn't noticed it to be abnormal. Anyone have any idea how often these head gaskets go? I have a 95 accord wagon with a 2.2 VTEC and 30k more miles then my wifes 97 non VTEC and I have had no engine issues, yet.

bdmlilburn

i have been having similar problems. i think my headgasket needs replacing. seems like the bubbles just keep coming. i also have a rough idle at start then after 10 seconds back up to normal fast idle-probably some coolant in the combustion chambers. when im driving around town on sharp turns the gauge will jump a lot meaning these is air in the engine. i also have a slightly high hot idle. you definitely have a leak or air in the coolant though if its overheating while moving in gear. it should overheat at idle too unless you rev it.

gonna try bleeding again tonight with the front jacked up and see if there is any difference

jdmcertified909

well i had a 1994 integra like 4 months back and head gasket was gone fans wouldnt turn on. there wasnt coolant leaking anywhere but my diagnosis led me to headgasket when i took off the head you could definitely tell the head gasket was gone replaced it and fans worked as soon as the car got warm.. and the bleeding your doing it wrong. its car off thermostat open. well at least thats how i have bigger success then with the car on and cold. i at least drive the car around let it get hot turn it off open bleeder and start bleeding it and filling the rad as it goes down. also another thing you can try is to gently squeez the hoses with the rad cap off but one at a time. sometimes it can be a PAIN!! to bleed these cars. youll probably even see bubbles come out when squeezing the hoses. but gently. and head gaskets can go anytime anywhere its all bout prevention. flush your cooling system at least 4 5 times with prestone flush. and install fresh honda coolant also to prevent stuck thermostat i would recommend fail safe i think i was called those are guaranteed to stay open when they go bad. also replace all hoses water pump. replace the whole cooling system if you just bought the car. fresh coolant fresh cooling system will asure a LONG life on that head gasket

WranglerBowman

I bought a combustion leak test from NAPA over the weekend and I def have a blown head gasket!!! I was wondering if anyone has some tips on replacing the head gaskets on a non VTEC 4 cyclinder?

nus_dogg

It's pretty straight forward. Just make sure to loosen the head bolts from the outside in if you know what I'm talking about. So you don't warp the head.

Roader

Not too bad. I took me all day one Saturday with hand tools. Since it's an LX, make sure you replace the oil restrictor o-ring. It's really easy to replace the oil pressure sender with the head off and they're only ten bucks or so. I didn't touch the timing belt; I just set it #1 @ TDC beforehand, marked the belt and cam with some whiteout, and flipped the cam up and out. Probably not per the FSM but it worked out fine. Check the head for flatness before you put it back together. Get it shaved it you have to. Mine was flat/needed no machining and, 10K miles later, the new HG is still working great.

Clay.hal

i'm having the same exact problem, but i just had a head gasket replacement less than two months ago.
96 accord lx 2.2l

WranglerBowman

I'm just gonna go ahead and have the head machined, even if I don't notice any warpage. Figure if I'm putting that much time into it better make sure it is all done right. I plan on replacing every seal I can get to with the head off, since the distributor O-ring leaks a lot of oil already. I'm hoping I can knock this job out over three evenings or so. I don't think the timing belt has ever been changed so I really want to have that done. Anyone else have any pointers or things to consider/replace before I start this job?

Roader

If you're replacing the timing belt then replace the water pump too. And you may as well adjust the valves while the valve cover's off.