[BRG75]

I would like to thank SD1too, who has vetted this content for accuracy, and added a few comments for completeness.

Whilst this site contains a wealth of information on cooling fans, may I suggest that for newcomers (or nearly new, like myself) some foundation information might help to put the detailed information into context.

I hope that this is not reinventing the wheel, but I was unable to find the basics in one place, and found myself having to piece it together.

TEXT

All Rover 75 / MG ZT's have 2 fans.

The FIRST simply circulates hot / cold air within the cabin, and is better described as a blower fan. It is located behind the dashboard.
This article is NOT about this fan, but it is mentioned, in order to eliminate the sound it makes, and a potential wrong diagnosis.


The SECOND fan is located in front of the radiator, and is a recognised problem area, although with the passage of time, it was, and still can be, made reliable.
The fan has two similtaneous functions, engine cooling and air condition operation. This is of assistance in basic fault diagnosis (excluding the very few cars without air conditioning)

Early cars were fitted with either a 2 speed fan (K series 1.8) or a 3 speed fan (KV6 & Diesel)

The different speeds on these fans were controlled by relays, which switched in additional brushes.
The brushes wore out, particularly the "common" brush, and were (in their day) considered unrepairable.
However, since around 2009, and still the case today, replacement brush sets are available. These appear to have varied in quality / cost, but the brushes from at least one supplier have stood the test of time.

MG Rover then changed the design, so that the fan speed was changed by the switching in or out, of a resistor. Unfortunately, the original resistor (silver coloured) was inadequately specified, resulting again in fan failure, but with different characteristics.

Inevitably, when the cars were current, a failed fan could have been "repaired" by:-

a) Replacement of the correct item, shall we say factory sourced.
b) Replacement of either the correct or incorrect item, say breakers yard sourced.
c) Changing from a brush to a resistor speed switched item.
d) Changing to an aftermarket fan, such as Kenlowe.

There is no known introduction / cut off date for the factory change, but it seems that both old and new design fans were factory fitted around 2002 and 2003. There are also reports to suggest that this continued to the end of production.

Regarding replacement brushes for the earlier units, it is not known (to the writer) if both 2 and 3 speed versions used the same brushes.

October 23rd - An article today, with photographs, strongly points to the brushes being the same dimensions.

However, following a phone call yesterday, a set of 4 brushes (3 speed) are available from "Engineering Carbon Products" who still list them on their website.
If the 2 speed units do indeed use the same brushes, they will now sell a set of 3.
If the brushes are different, they can still manufacture replacements from a pattern, or dimensions.

It should also be noted that when the resistor fans came out, all variations were fitted with 2 speed units.

In summary, it is essential to know what fan is presently fitted to your car, before reading up on the (very detailed) test procedures to be found on this club site.

Early 2 speed (3 wires, take off front bumper to identify)
Early 3 speed (4 wires, take off front bumper to identify)

Later 2 speed (2 wires, resistor visible at 2 o'clock, through radiator grille)

Any Silver resistors should be replaced with a Gold one.

I hope that this is of assistance

BRG75