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Hi,

Yesterday while waiting at a light I noticed my temp gauge was starting to rise ( about 3/4 up from cold). Once the light changed and I started driving it went back down to normal. It happened again at the next stop, and went back down while driving. It was about 26 C out in full sunlight, this was definitely the warmest day I've driven it this year. I turned the heater on full blast to try to relive the temperature, heater was blowing blazing hot.

I mention the heater b/c of a post from this thread http://www.mx-3.com/phpBB3/viewtopic.ph ... verheating talking about if car overheating and the heater is blowing cool it could be a sign the water pump isn't working properly. Heater blows hot. Also water pump was replaced about a year ago.

I parked the car and checked the coolant reservoir, it was full. I did notice a very slight dampness around the rad cap but nothing dripping, just a bit damp. I saw in another thread that it may be a bad rad cap, could that cause this problem?

I think the fan isn't spinning up, my theories are bad fan, rad cap, or bad thermostat, I also noticed in this thread http://www.mx-3.com/phpBB3/viewtopic.ph ... verheating had some posts that sometimes the fan isn't connected properly due to loose connection.

I am at work right now, I was planning on checking it out tonight, but was hoping to get some insight on what to check from you guys!

My questions, in short form, are
1. does dampness around rad cap mean bad cap? Could that cause this problem?
2. overheating only when not moving, bad fan or could it just be thermostat or a sensor or something?

EDIT: re-read that first link, looks like possible bad relay, thoughts?

The fan's not turning on, check the fan motor, the relay, and the wiring.

If it does not turn out to the the fan itelf or the relay, the large connector for the main harness connector for the rad wiring harness is very susceptalbe to corrosion. This is right in front of or under the air filter housing.
A good indication will be when you try and split it is if it does not come apart easy or at all like in my case.

_-Night-Shade-_ wrote:The fan's not turning on, check the fan motor, the relay, and the wiring.

+1

The fan only comes on when you are stopped (since there's no airflow because you're not driving).

ty, will check after work

Assuming the problem is that the radiator fan is not turning on…
I went through similar troubleshooting for the radiator fan not long ago – so it is fresh in my memory.
Everything you need to know to test the radiator fan and related components (temp sensor, relay, wiring) is in the online manual E2-11 thru 14 starting here.

Definitely test the fan first by connecting TEN and ground, turn ignition to ON position and open the throttle. You can also just idle the engine and wait for it to get hot and see if the fan ever turns on – just monitor the temp and don’t let it overheat. I found my problem was with corrosion at the fan connector as korpit suggested above.

didnt read most of it. but check ur coolent level when its cold. my mx and a buddies mx did this and it was because the coolent level was low. and it wasnt circulating at a idle but it was when driving.

Agree with everyone Fan for sure. nothing else would cause it only at idle

ok i read it all this time.
well how long does it take for the temp to raise at an idle and how fast does it raise when it starts to.
because even without fans and just good circulation it shouldnt rise very fast at all. (unless its like 90 - 120 degrees out)
and a bad radiator cap would screw up the circulation. (more at an idle then high rpm)
when your temp starts goin up raise the rpms for a few sec's to see if the temp goes down.
then you either have a bad cap. or a big air bubble in the line somewhere.

I remember I did this test out of curiousity on my fully functioning K8. It took about 6 minutes idling for the fan to come on. On my ZE it takes much less than that though, maybe half.

if you have a bad rad cap you will have similar issue. just remember that for each 1lb of pressure is 4 degrees farenheit. if you lose 6 lbs of pressure from a bad cap that lowers the ability to cool by 24 degrees!!

Hey guys, thanks for all your replies. I checked it out, I was mistaken about the residue near rad cap by the way.

I jumpered TEN and GND, and turned the key to the 2nd accy setting (power windows work, inside fans blow) and manually turned the throttle, no fan

There are 2 fans actually. the one on passenger side turns on if I turn on the ac, the other one I've never seen on.

At idle, to reach operating temperature, I am only guessing but around 5-10 minutes. driving, about 4 minutes or so.

I checked my fuses, one was for the fan, was ok. The relay I tested for shorts across the power leads and the control leads, no shorts. I manually actuated the relay with a 12v ac adpator, it clicks when powered.
EDIT: I didn't check for short across big leads when relay actuated, not enough hands.

I pulled out the resonator thing on my air intake to have a look, fan connection looks fine, I reseated it. I also noticed there was a 2 wire connector that wasn't plugged in. See pic. Reconnected it, didn't make any difference for the fan coming on.

http://picasaweb.google.com/lh/photo/vA ... directlink

That pic is taken from front of car. I circled the connector (faintly). The fan hidden behind the plastic in bottom of the image. The connector does not appear to connect to the fan.

Driving around then idling, it isn't overheating anymore, but it was much cooler on the 21st when I checked. Personally I don't think I fixed anything. I'll check out that guide that davmac linked to.



EDIT:

I was checking the connector on the AC fan, not the rad fan! Wow. Ok I have more to check tonight!

rad fan was disconnected. I reconnected it, jumpered TEN and GND, no fan movement. tried driving it, let it warm up, still no fan. It wasn't overheating today and it's a scorcher out there, about 28C. Not sure whats up, the fan doesn't seem to be moving, but its not having problems now.

Test the fan motor by connecting it to a 12v source like the battery, as outlined in the manual.

You might check the air bubbles in the radiator..It is a reason that the fun can not work
Before a fed days i changed the waters.When i put the new water the fun wasn't working..It was the air the reason that the fun couldn't work.To put out the air you must do this
Open the radiator cup and start rising the rpm engine from the throttle.Do the rising again and again.you will see air bubbles coming out.Repeat it until the fun starts working.
If it doesn't work empty the water and start your engine.As you filling the radiator with water you will push up the rpm in the same time.Do this until the radiator is full.