is my alternator foobared

[g40chris]

i broke down tonight and the breakdown service said when he was checking the power of battery with a multimeter and he said that the power was fluctuating as if the alternator was charging then not charging then charging again then dropping off altogether so the car cuts out

he reckons the battery is fine though

i think that there may be a break in the wire somewhere

[Weeman]

Sounds more like the diodes in the output that turn the ac to dc current have failed.

It is fixable by a specialist who rebuilds them, or find a recon one.

Would keep an eye on your battery like as it will have be flatterned to it's limit with does them no good. If you can, take it out the car and charge it over night as leaving it flat causes damage!

[g40chris]

i got a mate that might be able to look at the alternator for me

the diodes are in the alternator are they

[Weeman]

Yeah they sit I'm a black box ( sometimes a different colour) that is normally screwed to the outside of it near the output bolt that goes to the battery.

Tis any easy job to fix if you can get tbe parts. 

[g40chris]

does anyone know the exact part number

the only one resembling this on etka i can find is part number 068 903 803 D

but this doesnt show what type of alternator its for?

can i get to this without taking the alternator off as i have taken the alternator off about 20 times in the last 6 months

[scotsjohn]

Brush/diode pack's generic for most Bosch alternators Chris; about £10 at most. A two minute job to change. All those times you've removed the alternator have been good practice mate. It's going to be one more time I'm afraid.

[g40chris]

no probs, will take it out tomorrow after work. so the brushes/diode regulator should be the same as standard polo items.

[g40chris]

picking a new one up from GSF later £9

[g40chris]

dont tell me that now hahaha

well i got the old one off, waiting for the misses to pick up the new one on her way home from shopping

[g40chris]

right i fitted the new one from GSF and re-fitted the alternator. tested battery before running it and the battery was 12.5volts, started car and only got 12volts. gutted. so i fiddled abit with all the 2 wires and took these off the alternator and replaced them tried again and was getting a lovely healthy 14volts.

i got a sneaky feeling this will show its ugly head again if all i done was fiddle with the terminals. i know on an old alternator the terminal bolts had come loose from the inside of alternator and a mate fixed it for me. just hope its not the same as that one. thinking of getting a voltmeter just to keep an eye on it.