JENNY_EG6

Okay.. it doesn't really overheat but it gets to about 70-80% and the fan would kick on , and temp would drop back to normal. Things I've checked:

Fan DOES kick on.
Thermostat DOES open
NO coolant leak anywhere.
Radiator is NEW
Thermostat is NEW
NEW water pump
Head-gasket was replaced 2 months ago (Head was resurfaced too)

I had the car at idle for about 30 minutes the temperature would go about 70% and just drop back down when the fan kicks on. Did that for a couple times, but no sign of going anywhere above that.

Could anyone tell me what this could possibly be? I'm getting frustrated and I need this fixed before tomorrow for class and work Any help/suggestion would be greatly appreciated. Thanks Honda-Tech!!!

grumblemarc

iTrader: (4)

Air in system.

JENNY_EG6

Checked that also, there's no air. I'm having a friend over with a Coolant tester to see if I have a leak in the cooling system. Thanks!

frankenghia

lazy fan switch maybe?

motegicivic

By the way post your car and year and stick or auto.

I have the same issue, happens every now and then.

Only happens at idle right?

Since you had the head gasket done, sometimes that is the silent killer, I would rule that out.

Double check for air.

Change the fan switch anyway if you did not do it.

JENNY_EG6

My car is a manual I just flushed the coolant system so no air, haven't tried fan switch, but a mechanic told me to change the coolant temp. sensor so I'll try that first.

EL MIGGZ

iTrader: (2)

i would try the coolant temp sensor and if that doesnt work maybe a new thermo but with lower degrees?

frankenghia

are you talking temp sensor or ect sensor?

JENNY_EG6

Yea Coolant temp. sensor I think I said that

frankenghia

You did say that but I am amazed at how many people say one but mean the other. Just making sure.

JENNY_EG6

Oh.. ^.^ well hopefully it'll work if not I'll bug you guys some more for help.

motegicivic

The coolant temp sensor can be tested first, should read between 200 to 400 ohms, I tested mine it cam in like 342, I doubt that is your problem, it is basically for the computer.

Just double checking happens only at idle right?

strategy400

Sounds like the fan is not coming on in time. ECT most likely (or air in the system). Unless the gauge is reading falsely.

JENNY_EG6

Just tried a new ETC from AutoZone, now the fan kicks on even later than before, overheating problem got worse.

and the over heating problem happens usually after I drive around (when car's fully warmed up) doesn't do it when car's rolling since there's wind to cool it down, but at stop lights it usually goes back up.

motegicivic

You got the right part?? Just in case put back the old one.

Take my advice, get a new fan switch, like 22 bucks and easy to do.

JENNY_EG6

Ok I'll try that. thanks

RICKSAUTOMOTIVE

like motegicivic says, change the fan switch. we replace fan switches and thermostats together in my shop.

if that dont solve the issue, try a few other things. you never said the year of your car,--is it an OBD2 year? if so, most descent OBD2 scanners have a live data feature that will give you an acurate ECT reading and allow you to rule out a bad gauge. with the different reading from a new sensor, i would guess the gauge is fine, but you never know.

next, when you bled the air from the cooling system, did you have the heater on? you did drain most of the coolong system with the new head gasket and water pump. maybe you have air trapped in the heater core.

and the temp on the thermostat should be an OE temp. I know there are others for preference but I always use the OEM temp thermostats from autozone. sometimes I have to wait a few hours for them to get it, but I wait and go back to pick it up.

keep us posted. Thanks

motegicivic

When you get a live ECT reading, I assume it give you the running temperature, does it give you any other readings?

Syndacate

Yeah but it's probably just a potentiometer, so where it lies between 200 and 400 ohms determines what it's returning to the computer, which determines when the fan kicks on.

That being said, it's for the computer, yes, but if I recall correctly there isn't a direct connection from the coolant temp sensor to the fan relay. The fan relay is switched by the computer, so the computer still needs an accurate reading.

That's the way it is on Accords, pretty sure it's wired the same way on Civics of 5th and 6th gen.

Where is this other temp sensor you're speaking of? I've never heard of it nor replaced it. The only other temp sensor I know of is the IAT, which has nothing to do with the fan kicking on...I'm not sure if you're talking about that? If not, please enlighten me as to the what, where, and the functionality of said sensor?

JENNY_EG6

Problem solved, Autozone gave me a defective ECT sensor, my mechanic had an extra single cam on the side and threw his in. Car idled for an hour at the half line. Thanks all!! Hope this is a good reference to those who experience the same problem.

JENNY_EG6

I'm pretty sure you know the ECT is under the dizzy, the other one he's talking about is the temp sensor that's on the Thermostat, from what I've heard those doesn't usually give out (reason why I didn't change it).

motegicivic

I changed mine and it made a hugh difference, just so you know.

motegicivic

[QUOTE=Syndacate;46326149]Yeah but it's probably just a potentiometer, so where it lies between 200 and 400 ohms determines what it's returning to the computer, which determines when the fan kicks on.

That being said, it's for the computer, yes, but if I recall correctly there isn't a direct connection from the coolant temp sensor to the fan relay. The fan relay is switched by the computer, so the computer still needs an accurate reading.

The thing is I think the fan switch on the thermostat housing turns on the fan not the ECT sensor under the dizzy and no direct relation.

I think the ECT just gives the computer feedback on running temps for it run properly aka. start ups, running lean or rich etc.

Fnix

iTrader: (1)

Is the car actually overheating or does it think it is? Faulty sensor?