Ha! Just been there. Ancient tractor with no ignition warning light at start up. Initial investigation found ample carbon left on alternator brushes so assumed the fault was elsewhere. Not so:-( The alternator slip rings were worn down to the underlying insulation leaving a narrow strip of copper either side. As a temporary fix, refacing the brushes regained contact and the system is temporarily working.
Seems odd the copper wearing faster than carbon but maybe this was a recon alternator.
Or just on it's 19th set of carbon brushes
I've fixed quite a few alternators over the years, and never seen severe slip ring wear. Perhaps the operating conditions of a tractor were the reason - the fan in the alternator passes air through it. And dust etc could cause more wear.
IMHO, 90% of alternator faults can be sorted by a new regulator. Mechanical wear - except at a massive mileage - pretty rare here. The other about 10% a failed diode, fixed by replacing the pack.
Certainly the alternators I've seen fail it has been either the diodes or the regulator in all but one case, when the bearing failed. However, that case wasn't even an especially high mileage car- as I recall may be
40k. I certainly wouldn't consider mechanical faults or brush wear to be common.In message snipped-for-privacy@davenoise.co.uk>, "Dave Plowman (News)" snipped-for-privacy@davenoise.co.uk> writes
As TNP says, probably not the first set of brushes. Tractor used for hedging so certainly lots of wood chip in the vicinity. Hour meter on
9000 plus so I'm not hugely surprised.
The one you've missed out is one of the bearings coming loose and allowing the shaft to slide a little, so that the fan catches on the casing.
Once I could see where all the noise was coming from, I decided it was okay to get me home. I later disassembled it and re-fixed the bearing.
SteveW
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