Technical dead alternator

[Jai]

so with a little jiggery pokery, it's been established the alternator is dead, not a major issue, after all i have 5 others, but the problem is, as i recall it, it's a right ballache to change out, and what i don't want to do is swap in another one, to find it is dead too.

so, how do i test an alternator is ok, when it is not on the car?

 

[dave]

i take mine to a rewinders, they test um

 

[Louie Bee]

I'd start by looking for the altanator with the truest pulley - spin it and look for bends. inbalanced fan blades arn't good. Also listen for noisy bearings (they zap power too)

Turn the pulley fast and measure the voltage at the output. Maybe a little help from a drill?

It's only 2 mounting bolts, 3 bolts to remove the end cover and 1 to remove the HT wire IIR. Don't forget to remove the battery

Can't you invite Chas over for half an hours fun?

I seem to recall he likes it when electrics don't work by altanator number 5, he'll have it down to a fine art

 

[Jai]

I'd start by looking for the altanator with the truest pulley - spin it and look for bends. inbalanced fan blades arn't good. Also listen for noisy bearings (they zap power too)

Turn the pulley fast and measure the voltage at the output. Maybe a little help from a drill?

It's only 2 mounting bolts, 3 bolts to remove the end cover and 1 to remove the HT wire IIR. Don't forget to remove the battery

Can't you invite Chas over for half an hours fun?

I seem to recall he likes it when electrics don't work by altanator number 5, he'll have it down to a fine art

will have a shot at it tmrw, provided teh dread manflu doesnt keep me indoors, besides i think i'm in the bad books with chas, everytime he comes over for a "quick job", it turns into a marathon session fighting with the car, getting covered in grime and cack, and as of last sunday, being exposed to my infectious fluness

 

[alexGS]

Jai is right, I seem to recall it was so much harder to change the alternator on the Turbo than it was on a normal Uno... Though it's simple in principle, in practice it's a fiddle (driveshaft out, if I remember correctly).

The alternator usually needs the 'exciter' wire (thin wire attached that controls the warning light) in order to begin charging. That's why the warning light has a bigger bulb than the other warning lights - so the warning light wire provides enough current to get the alternator going. Remember this if you're testing on a bench with a drill - apply 12v through a 5W bulb to the small terminal on the back. Ground the body of the alternator. Then spin and measure the voltage on the large terminal (10mm nut).

Usually if you have two alternators, you can make one good one as the failure is either brushes, voltage regulator (integral with brush holder), or main rectifier diodes (you need a BIG soldering iron to remove diode pack).

As Louie says, the bearings should be replaced (need a three-legged puller). Well, I reckon it's worth fitting new bearings, anyway. They're an easy-to-get size, and not expensive.

It may be easier to get the alternator rebuilt and tested if you don't already have the spare parts. Oh that's right - you said you have five of them

Good luck!

-Alex