newbie with a cooling fan fault

nick.g · 7th November 2007, 09:41

Hi everyone ,i have trawled through your forum which is great, but have managed to confuse myself as to whats wrong with my cooling fan and water temp'.
I have a 1.8T zt 03 plate an have noticed cooling system gets very hot, fan does run when temp' gets high sitting in traffic, sounds like high speed(hovercaft noise as many of you describe it).
When aircon on it runs continously at high speed. Ihave checked to see if there is a resistor but there is not.
Any help would be much appreciated.
P.s i have looked at front bumper removal ,looks great fun but thought i would ask b4 attempting.
many thanks, nick.

JohnDotCom · 7th November 2007, 11:24

to the Club, and as you have found plenty to read and see.
I am not quite into Petrol cars as Diesel, but I know they can suffer from HGF so it is critical that you monitor your water level in Expansion tank.
It does sound as if the Motor control box has packed up, either the brushes or other parts within.
You may in the end require a new complete unit, but
Someone will be along shortly to assist you properly soon.

AURORA MG · 7th November 2007, 18:24

Quote:

Originally Posted by nick.g

Hi everyone ,i have trawled through your forum which is great, but have managed to confuse myself as to whats wrong with my cooling fan and water temp'.
I have a 1.8T zt 03 plate an have noticed cooling system gets very hot, fan does run when temp' gets high sitting in traffic, sounds like high speed(hovercaft noise as many of you describe it).
When aircon on it runs continously at high speed. Ihave checked to see if there is a resistor but there is not.
Any help would be much appreciated.
P.s i have looked at front bumper removal ,looks great fun but thought i would ask b4 attempting.
many thanks, nick.

Why not give us a call, we are fairly close to you near Rainham. Click on the signature below. I am not technical so can't give advice.

David3807 · 8th November 2007, 16:05

Nick,

My guess would be the slow speed brushes have worn out in the fan motor and it no longer functions at slow speed.

Thus when the engine starts to heat up the ECU first calls for slow speed fan cooling which doesnt work and the temp continues to rise. That results in the ECU calling for max fan speed giving the hovercraft noise and hopefully a reduction in engine temp.

Usual remedy is a new fan I am afraid although some members have had success in replacing the brushes but that assumes the commutator is still serviceable which it often is'nt.

David

Have sent you a PM (private message). Access is by clicking the private message box at the top right of this page.

Keith · 8th November 2007, 16:12

my guess being it is a 1.8T using a three wire motor is that it is doing exactly what it should

T-Cut · 8th November 2007, 16:40

Quote:

Originally Posted by Keith

my guess being it is a 1.8T using a three wire motor is that it is doing exactly what it should

But he doesn't have the resistor. (?)
Of course it would run this way if the resistor had been taken off. (?)

TC

stocktake · 8th November 2007, 16:48

Quote:

Originally Posted by T-Cut

But he doesn't have the resistor. (?)
Of course it would run this way if the resistor had been taken off

TC

Does the 1.8t have a resistor? didn't think it did?

T-Cut · 8th November 2007, 18:55

All 2-speed fans have a resistor, whatever the engine.

TC

stocktake · 8th November 2007, 19:09

Quote:

Originally Posted by T-Cut

All 2-speed fans have a resistor, whatever the engine.

TC

Oh, I am confused now........... I have motor in my shed its a 450w motor that is three wire with two relays in the box. no resistor fitted, looks like never had one fitted. All original wireing. and all still in its framework
Got it from a breakers yard.

When I have power to the motor and power each relay they bring the fan on!

My head hurts now T cut...... I presumed it was from a 1.8 , sorry

Keith · 8th November 2007, 19:37

The 1.8 typically (as there are bound to be some variations) has a physically smaller three wire motor for the two speeds (look at the pics in my fan thread)
No resistors and two ground brushes wired in parallel

Hence we get less people with faults on those

7th November 2007, 09:41	#1
nick.g Newbie mg zt Join Date: Nov 2007 Location: kent Posts: 4 Thanks: 0 Thanked 0 Times in 0 Posts	newbie with a cooling fan fault Hi everyone ,i have trawled through your forum which is great, but have managed to confuse myself as to whats wrong with my cooling fan and water temp'. I have a 1.8T zt 03 plate an have noticed cooling system gets very hot, fan does run when temp' gets high sitting in traffic, sounds like high speed(hovercaft noise as many of you describe it). When aircon on it runs continously at high speed. Ihave checked to see if there is a resistor but there is not. Any help would be much appreciated. P.s i have looked at front bumper removal ,looks great fun but thought i would ask b4 attempting. many thanks, nick.

7th November 2007, 11:24	#2
JohnDotCom * Rover 75 FaceLift Tourer CDTi 170BHP Auto ConnSE 2005 Model Starlight Silver Join Date: Nov 2006 Location: Abergele Posts: 28,735 Thanks: 0 Thanked 6 Times in 5 Posts	to the Club, and as you have found plenty to read and see. I am not quite into Petrol cars as Diesel, but I know they can suffer from HGF so it is critical that you monitor your water level in Expansion tank. It does sound as if the Motor control box has packed up, either the brushes or other parts within. You may in the end require a new complete unit, but Someone will be along shortly to assist you properly soon.

8th November 2007, 16:05	#4
David3807 Posted a thing or two 2002 R75 Conn SE 2.5l Auto Tourer, 2001 R75 Conn SE 2.5 Auto Saloon Join Date: Nov 2006 Location: Gravesend Posts: 1,897 Thanks: 0 Thanked 2 Times in 2 Posts	Nick, My guess would be the slow speed brushes have worn out in the fan motor and it no longer functions at slow speed. Thus when the engine starts to heat up the ECU first calls for slow speed fan cooling which doesnt work and the temp continues to rise. That results in the ECU calling for max fan speed giving the hovercraft noise and hopefully a reduction in engine temp. Usual remedy is a new fan I am afraid although some members have had success in replacing the brushes but that assumes the commutator is still serviceable which it often is'nt. David Have sent you a PM (private message). Access is by clicking the private message box at the top right of this page.

8th November 2007, 16:12	#5
Keith This is my second home ZT400 Join Date: Oct 2006 Location: Ellesmere Posts: 5,948 Thanks: 0 Thanked 43 Times in 29 Posts	my guess being it is a 1.8T using a three wire motor is that it is doing exactly what it should

8th November 2007, 18:55	#8
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,753 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	All 2-speed fans have a resistor, whatever the engine. TC

8th November 2007, 19:37	#10
Keith This is my second home ZT400 Join Date: Oct 2006 Location: Ellesmere Posts: 5,948 Thanks: 0 Thanked 43 Times in 29 Posts	The 1.8 typically (as there are bound to be some variations) has a physically smaller three wire motor for the two speeds (look at the pics in my fan thread) No resistors and two ground brushes wired in parallel Hence we get less people with faults on those