Checked brushes - worn down to locating hole in brush. Length seems ok - spring tension ok. Still charges - sometimes Are brushes available? Could the regulator be faulty? Can regulator be purchased separately, if so what is guide price (Aussie dollars). What tests can I carry out? Can I bench test the alternator?
You can bench test it but u need to have something to turn the alt up to speed but thats not needed check your voltage make sure its between 13.00 to 14.85 anything under that then the alt is not charging anything over that then the reg is bad and if the reg is bad then just replace the alt the cost of a reg is more then the alt brushes can be found at any repair shop for starters and alt let me knoe how it goes
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In case battery is Bad. Stop Engine
Try a substitute Battery... Just use Jumpers Cables with main battery disconnected. Restart
If no change in Voltage (should go up to 13.8 to 14Volts) then your Alternator is Bad. (Belt Not Slipping?)
The Voltage regulator is usually built into the Alternator these days. So...Remove Alternator.
Either Repair it.
Place in Vice. Mark the case next to the screws with a scratch so it lines up on re assembly. Undo screws & Separate.
Faults Usually - Brushes, Diodes or Regulator
Check Brushes are not worn down too far to make contact.
If replacing brushes you will need to make a brush hook to hold brushes back on reassembly. Look for small hole to insert brush holder until both halves are back together.
or Get a Rebuilt one with warranty.
have the alternator removed and the slip rings on the rotor cleaned and machined . Replace the brushes and have the unit bench tested . When this happens it is an indication that the brushes cannot maintain contact with the slip rings either from lost spring tension --dirt on the rings and rings badly scored
The charging problem should be fixed first, pursue the other alarms later if they still exist.
You probably have worn alternator brushes, causing the intermittent 'BAT' warning indicator.
Get the alternator re-checked,
- ensure alternator and battery grounding connections are all ok.
(The battery terminal voltage should be approx 14.5v with the engine running with a load such as headlights on or heater blower motor running).
Check your battery terminals are not loose or corroded.
Check your alternator dive belt tension is OK.
If no problem with drive belt, it may be worn alternator brushes.
If the problem persists get the alternator checked.
It should be either just above the air conditioning compressor, or on the opposite side. It will have two wires coming out - a red wire ( 12 volt plus) and a black ground wire. The a/c compressor has metal fittings and rubber hoses as well as a clutch. No need to touch the a/c compressor.
I changed alternators on my 300D models and 300 SD. They are very much the same.
You will need to loosen the adjustment slider and physically slide the alternator to loosen the belt. Remove the wires from the alternator - probably a plug at the rear. If the car has a single serpentine belt the problem is more complex because so many units run off the same belt, including the water pump, fan and a/c compressor. Restoring proper tension is critical.
The alternator swings in a vertical arc on a long bolt on the bottom or side that runs from front to rear.
Replacement is not difficult - hold the new unit in place while you insert and tighten the long bolt, then reposition the tension slider and tighten that bolt. The tension needs to be correct or else the belt will slip and squeal and your battery will not charge properly.
You may need a crowbar the achieve the right tension while you tighten the tension slide.
Instead of replacing the alternator altogether, why not just replace the brush on a round plate at the rear. Most alternator failures involve worn brushes. The rebuilders simply replace them and sell a "rebuilt" unit.
Make sure you can get brushes and/or a brush assembly before you start.. Loosen the tension but do not remove the alternator. Remove the two small nuts that hold the brush assembly at the rear and slide it off. Replace with the new one.
Be sure you retract the brushes so they will slip back over the armature, and align with the retaining screws. Tighten them. Re-tension the belt and you're home free. I have done this on the road when necessary.
Easier and cheaper than changing the entire alternator.
also some useful info
batterys are refurbed these days and sometimes an unlucky person can still get a dead cell battery several times even if the you bought brand new
i took mine back 4 times before i found a good one that kept its charge
dead cells dont show them selves very well on battery tests even though dead cell the tester would show good show dont think that there is something definatley wrong you could be in same ditch i was before with my batterys
alternator testers at some shops are not reliable enough i recommend a voltage tester to battery