Radiator fan problems

[T-Cut]

Originally Posted by pab

yes we are on the same topic,i think t-cut may be back soon with a bit more information.....hopefully

I'm not sure what more help I can give. The original motors failed at 50-60K miles due to the brushes wearing away. Repair isn't very successful and not worth the effort frankly. The later 2-speed design is more robust and doesn't seem to have the same weakness. These later fans are available as a kit and are plug and play with the existing wiring. They are quite expensive from MGR spares outlets but they will probably last the lifetime of the car. There is however, a weakness in the design. This is the slow speed resistor which appears to be under-rated for the power demands. (The earlier system didn't use a resistor.) The resistor tends to fail, rendering the slow speed inoperative. The answer is to fit a higher wattage version. These are nominally 0.5ohm, 100 watt power resistors available from electronics retailers like RS Components or as a kit from eBay (£25 approx). Talk to member Jules, he sells the fans and the kit. However, you only need to worry about the resistor if your 2-speed fan actually fails to run at slow speed (eg. with the A/C system on Auto).
Fitting a replacement fan requires removal of the front bumper moulding. There are lots of threads on this and I'm sure there's a 'How To' instructional thread hidden in here somewhere.

[mihai75]

I don't have a resistor, so I think i need a new cooling fan kit. It's corect?

Radiator fan problem can be diagnosed at an OBD diagnosis?

[T-Cut]

You have the old 3-speed fan system. The slow speed has failed so you have to replace the motor. The usual way is to replace the motor and the fan (they usually get brittle and break in the mounting lugs). The replacement kits now available are 2-speed systems, but they are plug and play with the old wiring connectors.

You can't diagnose cooling fan problems using the OBD. Only a T4 computer will do that.

[mihai75]

Thank you all for advice. Now, my problem is how can buy a replacement kits with 2-speed systems. I can pay by credit card through PayPal. I don't see on eBay.

[Jules]

Hello Chaps!


Resistor kits here:
http://www.the75andztclub.co.uk/foru...ad.php?t=27389


Complete Fans here:
http://www.the75andztclub.co.uk/foru...ad.php?t=24506

If you PM me I can send you my Paypal details.
Parts posted out the same day
Please make sure your Full postal address is included

Regards
Jules

[Gman2]

Originally Posted by T-Cut

I'd have thought a 2000 reg would have the earlier 3-speed system. Sounds like a typical worn out fan motor.

What is the mileage?

Any idea what reg the two speed fan was introduced?

[JohnDotCom]

It varied wildly I'm afraid.
From around 2003 or MK2's but some 2004 had 3 speed
so..............

[T-Cut]

Originally Posted by Gman2

Any idea what reg the two speed fan was introduced?

It seems there was no exact point, its fuzzy. It certainly started in late 2003, but there doesn't seem to be a VIN reference to go by. It seems the two types were installed at the same time for quite a while, even into late 2004.


JDC Snap!

[Jules]

Originally Posted by T-Cut

You can't diagnose cooling fan problems using the OBD. Only a T4 computer will do that.

Oh but I think you can to some extent T Cut, thanks to your informative thread here!!
http://www.the75andztclub.co.uk/foru...ad.php?t=29584

You can go to OBD option 19/7.0 and see when (if at all!) the different fan speeds kick in.

I have summarised the Temperature ranges for the different engine options below:

OPERATION

K1.8

Engine Running
If the ECT sensor registers a temperatures of;

Between: 98 °C and 104 °C, = Low fan speed
Between 105 °C and 112 °C, = High fan speed

The ECM switches both cooling fan relays off if the ECT sensor registers a temperature of 98 °C or lower.

Engine Stopped:

Above 112 °C = High speed relay

The cooling fan motor is now able to operate at high speed until the ECT sensor registers a temperature of below 112 °C.


KV6


If the ECT sensor registers engine coolant temperatures of:

Between 96°C and 100°C, = Low fan speed
Between 102°C and 106°C, = Medium fan speed
Between 108°C and 112°C, = High fan speed

Air Conditioning Request
If air conditioning is requested, the cooling fans will automatically operate at medium speed, even if the engine coolant temperature is below 96 °C. If an air conditioning request is received by the ECM when the cooling fan is running at low speed (i.e. the engine coolant temperature is between 96 °C and 100 °C) the ECM will increase the fan speed to medium. If the engine coolant temperature rises above 108 °C the cooling fans operate at high speed as described previously.


M47R Diesel

If the ECT sensor registers an engine coolant temperatures of:

Between 100°C and 105°C, =Low fan speed
Between 106°C and 111°C, = Medium fan speed.
Between 112°C and 119°C, = High speed.

For 2 speed motors IIRC the ECU energises SLOW speed for a larger temp span.
For example in the diesel engine:

From 100 Deg C to 111 Deg C = Slow Speed
From 112 Deg C to 119 Deg C = High Speed

Taken from RCL 0311ENG
Please bear in mind if you are relying in the On board diagnostics for readouts, this assumes your Temp sensors etc are still in Spec. But probably good enough for above motor tests

[FROGGY]

Originally Posted by Jules

Oh but I think you can to some extent T Cut, thanks to your informative thread here!!
http://www.the75andztclub.co.uk/foru...ad.php?t=29584

You can go to OBD option 19/7.0 and see when (if at all!) the different fan speeds kick in.

I have summarised the Temperature ranges for the different engine options below:

OPERATION

K1.8

Engine Running
If the ECT sensor registers a temperatures of;

Between: 98 °C and 104 °C, = Low fan speed
Between 105 °C and 112 °C, = High fan speed

The ECM switches both cooling fan relays off if the ECT sensor registers a temperature of 98 °C or lower.

Engine Stopped:

Above 112 °C = High speed relay

The cooling fan motor is now able to operate at high speed until the ECT sensor registers a temperature of below 112 °C.


KV6


If the ECT sensor registers engine coolant temperatures of:

Between 96°C and 100°C, = Low fan speed
Between 102°C and 106°C, = Medium fan speed
Between 108°C and 112°C, = High fan speed

Air Conditioning Request
If air conditioning is requested, the cooling fans will automatically operate at medium speed, even if the engine coolant temperature is below 96 °C. If an air conditioning request is received by the ECM when the cooling fan is running at low speed (i.e. the engine coolant temperature is between 96 °C and 100 °C) the ECM will increase the fan speed to medium. If the engine coolant temperature rises above 108 °C the cooling fans operate at high speed as described previously.


M47R Diesel

If the ECT sensor registers an engine coolant temperatures of:

Between 100°C and 105°C, =Low fan speed
Between 106°C and 111°C, = Medium fan speed.
Between 112°C and 119°C, = High speed.

For 2 speed motors IIRC the ECU energises SLOW speed for a larger temp span.
For example in the diesel engine:

From 100 Deg C to 111 Deg C = Slow Speed
From 112 Deg C to 119 Deg C = High Speed

Taken from RCL 0311ENG
Please bear in mind if you are relying in the On board diagnostics for readouts, this assumes your Temp sensors etc are still in Spec. But probably good enough for above motor tests

Not much use for a diesel owner when he is unlikely to ever see a coolant temperature as high as 100° (unless he lives in Australia!).

Mick