Tim 95 M3

I know this sounds similar to another thread on this forum but I also have a 93 accord, 309k miles, which overheats (3/4 the way) when at a long traffic light idling. It wasn't even that hot out, and this car has a history of doing this. The fans DO come on (edit: didn't realize there were two fans, I'm not 100% sure they are both coming on), when the car is shut off. So I know they work. There are no coolant leaks, the coolant looks healthy and I always keep it topped off. The waterpump is new. No signs of headgasket failure.

Possible things are going through my mind... air bubbles in the coolant, bad thermostat, bad fan switch, gunked up radiator (Can the radiator be gunked up when the coolant looks perfect?

What you do people suggest? I don't mind replacing a thermostat/rad or switch - is there a way to test the fan switch?

Thanks

deserthonda

the fans ( BOTH ) are also supposed to come on while engine is running and t-stat has opened up.....
make sure that both top and bottom rad hoses are about the same temp.. if the lower hose is only warm t-stat is sticking closed or partially closed thus fans won't come on, or come on late.....if t-stat works ok when temp needle on gauge is aroung 1/2 both fans should come on if they do not , you could have a bad fan switch located on the t-stat housing,just unplug the connector and jump the 2 wires together, if fans come o it is a sigh of a bad fan switch , ,, if only 1 fan comes on, you could have an issue with bad fuse, fan motor, wiring , ,,

Tim 95 M3

I have never changed the coolant in this car - is there a special procedure to get air bubbles out, or do they naturally find their way to the overflow tank/etc?
Thanks for the detailed reply, I'll take a look at all of that stuff and post back

Should both fans turn on/off in synchrony? Or are they wired in a stepwise manner...ie: one comes on, then the next?

dtapia

they come on at the same time. also check the flow if a fan motor is failing the brushes will not provide the correct current to be applied to the fan and will spin slower then normal.

Tim 95 M3

So, I did some work on the car but there's still an oddity about it. The fans turn on/off in synchrony when the AC compressor is engaged, but the fans do not turn on if the AC isn't on. Is that normal?

Also, I replaced the thermostat because at operating temperature there was a major discrepancy between the temperatures of the upper and lower radiator hoses. I bled the air out of the coolant (with the engine NOT running) by adding coolant to the radiator, until no air came out for a solid couple of minutes.

But here's the kicker - the lower radiator hose is STILL cold, even at operating temperature. The car has 300k miles on the original radiator, and has a new water pump. Anyone know why the hoses are still different temps?

kronikally420

"I have never changed the coolant in this car - is there a special procedure to get air bubbles out, or do they naturally find their way to the overflow tank/etc?"


There is a 10 or 12 mm nut that releases air through the hole in the top when the thermostat opens. It is on the housing next to where the hose connects by your distributor, sort of. You should have your car running long enough for the thermostat to open, when you loosen the nut you should see some water and some air (the watter sputters) do this until its solid stream of water. It might help, having air in there throws it all off.


Feel free to correct me if i'm wrong. I am just learning myself

locosiete

well it could also be your rad in general if the lines are clogged it may not be getting good circulation

kc7

Hi, I hv similar problem before. You may want to check the water level of the radiator early morning when engine cold. If the water lvl is not up to the filler neck or for some reason the radiator did not suck enough water from the reserve tank to top up, your head gasket could be leaking.

Also, my fan and air cond wiring was tampered b4 and behave the way you describe yours (not sure if this is the original mode though). But now it has been rewired such that 1 fan tied to 1 a/c compressor. The other fan works independently. This is sufficient to cool the radiator as i hv change the radiator to double row type. Otherwise, A/c comp + 2 fan operate at the same time will take away substantial amt of hp.

Do you feel extremely cold when a/c/ is on and cruising the car at high speed or climbing up hill?

Tim 95 M3

I wanted to add the happy ending to my thread - I replaced the thermostat and all has been well for a month or so. It was pretty old - perhaps the original! Thanks for all the help.