The carbon brushes are held onto the commutator ring by spring pressure.
Carbon brushes can and do wear out.
The problem there would be trying to source suitable replacement parts.
A friend of mine recently refurbished the alternator on his 1983 VW Golf. I therefore have an account with HC Cargo who supply such parts. Identifying it would be the problem.
I’ve got to say I’m not averse to having a fo at stripping a fan motor down and investigating but whilst I think the modified socket is a genius idea I still see that there is a potential for skinned fingers if the spanner runs so close to the intercooler rad.
I think when I do mine I’ll be taking the bumper off...
Have you checked the integrity of the wiring, Colin?
To do this safely so you do not blow your ECU up, you MUST disconnect ECU connector and I would remove all relays too then you can cannot a load such as a bulb to each wire on each relay in turn to see if there is high resistance in any wire.
So, for instance, connect one end to battery +ve and the other end to say Pin 5 of relay 1503.
If you look at Fan 1511 on the wiring diagram, you will see Pin 2 of the fan is connected to earth so in order to test the wiring and the fan, you would apply 12V to Pin 1 but as you probably cannot access Pin 1, by working back you can see that you could apply the battery +ve to Pin 5 of relay 1503.
You could also apply power to Pin 4 of relay 1504.
If Pin 5 of 1503 spin the fan but Pin 4 of relay 1504 did not, it would suggest high resistance in the wiring between Pin 4 and splice E096 (which is the little
just above Pin 4 in the diagram. By methodically working through each wire connected to the fans, you can build a picture of the wiring integrity.
This is what I hope to do when I get sufficient time.
If you could apply 12V directly at Pin 1 of fan 1511 and a separate earth to Pin 2 of 1511 then this would test the fan in isolation. If it spun up in that case, you know the fan is good.
If you applied 12V directly to Pin 1 of 1511 and relied on the connected earth from Pin 2 of 1511 and it didn’t spin up then you would know the earth wire between Pin 2 and M4B earthing point was high resistance.
Similarly with fan 1512, although it is slightly more complicated here. You could earth Pin 5 of the connector at relay 1504 and apply power to Pin 3 of same connector. This should spin the fan but it doesn’t tell you what condition the wiring is in.
Chris speaks of resistances at some point in this topic and specifically that there may be enough power for one fan but not the other.
By systematically working through isolating each component and the wire between it and each and every connection point you can build a picture of the state of the wiring.
I guess a proper auto electrician would do initial checks like fuses and then look at the component and probably the wiring last of all. One thing is for sure they are VERY clever people when they can turn up and work through a system without a wiring diagram!!!
I hope I’m not teaching you to suck eggs here.
