405 Cooling fan how do I test it ?

bigdods · Post by **bigdods** » 25 May 2004, 01:39

Ok, 405 1.9 Injection , runs really well except at high speed .. go over about 75 and it heats up and the big STOP light comes on. Rad is full of water and the stat is fine (rad gets nice and hot as do the pipes). Checked the cooling fan and its doing nothing. Fuses all ok... Haynes manual says to check the fan you need to short out the sensor on the rad, if it doesnt run then get a new one. Great BUT the haynes manual says take the connector off and short out the two pins and guess what ? there are two connectors , on half way up on the left (facing into the engine bay) and one at the bottom on the right and they both have 3 pins ! Anyone got any suggestions of how I can test the fan before I rip it out and replace (a dirty job that I would like to avoid!)
Also got the old warm air to the windscreen cold air to the feet problem that a lot of others seem to have...going to pull the heater apart at the weekend and see whats what !

PowerLee · Post by **PowerLee** » 25 May 2004, 01:58

Hi
Whatever you do, GET THE FAN WORKING!
Overheated XU9J2 = WARPED HEAD very easily!
Ones a level switch & the others your fan temp switch.
Its the one in the left hand side, half way up you want, there should only be 2 wires in there, short this out & fan should run with ignition switched on.

bigdods · Post by **bigdods** » 25 May 2004, 18:46

Thx for the input....the connector does have 3 wires, but two are red and one is yellow. As this is a single fan model I assume the second red cable would be for the other fan if it was fitted. Anyway, I shorted pins 1 and 3 (red and yellow) and the fan worked (hurrah!). Put a meter on the thermostat and that was switching too. So it had to be dirty contacts (even though I had alreay cleaned them once). So got to work and gave all the contacts a thorough clean and degrease, put it all back together and everything works a treat

Phew !
Now if I can just get the heater working.....

Homer · Post by **Homer** » 25 May 2004, 23:13

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by bigdods</i>

Now if I can just get the heater working.....
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
I think you may have an airlock. At 75mph it shouldn't matter if the fans are working (unless you are towing a caravan), there should be plenty of airflow through the rad without.

PowerLee · Post by **PowerLee** » 26 May 2004, 00:07

Hi
You do know that you dont get any air flow through the top grill between the lights.
If you do a lot of high speed driving or towing, take the grill off 2 x 10mm bolts & 2 x cross head screws & the clip for the safety catch.
Remove the grill blanking plates & get a lot more air flow to the top of the rad.

bigdods · Post by **bigdods** » 26 May 2004, 15:45

Lots of good advice ! I think removing the blanking plates sounds like a good idea. But maybe I do have an airlock. Checked the two bleed valves and both spurted water so I guess thats a good sign. But I think I will drain the whole system down and refill just to be sure.

Post by **RichardW** » 26 May 2004, 16:55

Cooling fan has no effect above about 30 mph. So, you either have a problem with the cooling system, or the warning light is faulty.
Once you have changed and bled the fluid, if the fault is still present I'd look for the bottom of the rad being cold (silted up), the thermostat not opening fully, or the water pump operating below par.

bigdods · Post by **bigdods** » 26 May 2004, 18:03

ok , well fixing the fan should stop it overheating while sitting traffic at least. I'm going to flush the whole system at the weekend and replace the thermostat...if that doesnt fix it then its a new water pump...
Thx for all the help

Homer · Post by **Homer** » 26 May 2004, 23:18

Where were the two bleed screws?
I would expect one near the thermostat housing, one on the input to the heater matrix and one on the rad (though my Cit doesn't have one on the rad).
You might have to cobble something together to get the water level high enough to push it up to the top bleed screw, often header tanks aren't high enough.

PowerLee · Post by **PowerLee** » 26 May 2004, 23:43

Hi
I wouldnt use the bleed screws, THEY SNAP VERY EASY!

Homer · Post by **Homer** » 27 May 2004, 12:50

Then how would you get air out of the system?
I have snapped the little valve cap style bleed scrw a couple of times. I just replaced it with a cap from the tyre valve. The plastic ones are best tightened by hand only. Though I sealed one of the others up using a self tapping screw on a BX.

KRISKARRERA · Post by **KRISKARRERA** » 28 May 2004, 18:00

Alright then, how do you test the rad fans on a 405 Mi16 with air conditioning? Cos they don't use that sensor in the radiator.

PowerLee · Post by **PowerLee** » 28 May 2004, 22:55

Hi
What year MI16 is it?

KRISKARRERA · Post by **KRISKARRERA** » 02 Jun 2004, 20:12

A 1990 G reg.