Thread: Dead Disco Alternator

If it's a 300Tdi Disco, it should be a 100A Magnetti Marelli. I'm told they are pretty exe to buy new but I don't see why they can't be overhauled for a reasonable price. If it's just worn out brushes, that's an easy fix. Not sure how hard/expensive a new regulator might be though.

Hi, mine stopped charging a while ago and it turned out to the be regulator. Regulator was faily expensive but only cost around $200 to get it fixed (I pulled it off and took it in). My symptom was an intermittent tacho before it failed. I priced a second hand on from SA and they were $450.

Cheers

Jim

How many amps is a 97 v8 disco's alternator ?

It is an Italian Job :roll: and 100amp. 8)

Bought a new one this morning at a cost of $435 plus GST and a $50 return cab ride from home to Newtown.(cheaper than a tow)

Old one out and new one in one hour.

The hardest part was detensioning the belt as I had an extra pair of hands the last time I tried this. :x

Eventually I used a double ended 15mm ring spanner on the tension pulley, a large screw driver throuh one end of the spanner leveraged off the waterpump and held there off the radiator with a block of wood. Haynes helped. [img]style_emoticons/<#EMO_DIR#>/biggrin.gif[/img]

I'll get a quote on getting the old one rejigged.

My tacho has been wavering for about 9 months. I thought I'd fixed it by fiddling with the connection at the alternator. But recently the wavering returned and as I took it out to 4000 rpm the tacho stopped probably with shock 8O. The other sign was that the battery light on the dash did not light up prior to starting.

The old unit was slightly different with an extended stud for attaching the resistor from the tacho feed. I attached this to one of the casing bolts in a different location.

Now happy and being a mechanical novice, a little chuffed

Originally posted by one_iota
My tacho has been wavering for about 9 months. I thought I'd fixed it by fiddling with the connection at the alternator. But recently the wavering returned and as I took it out to 4000 rpm the tacho stopped probably with shock 8O. The other sign was that the battery light on the dash did not light up prior to starting.

Had trouble like that before, thought it was the bulb. Flat battery not so long later was time to get serious and find out why. Got a nice grandfather to boost my batteries with his newish falcon for 15mins, just enough to limp home.

Pulled my alternator to bits. 8O Was sure some vandal had been let loose with a sandblasting hose in there. Brushes were down to the springs, commutator was burned and deeply scored, the rest had that sandblasted look.

With the amount of damage to the old one I just bought a new one of increased capacity (80amp, could power a town now) cost about $50 more than reco the old one but got a "betcha you can't bust it" 12mth warranty and the light working on the dash again. Still sings loudly when the spotties are on though to let me know it's okay. 8)

Kinda lucky being a mutant of the holden family, bits aren't that expensive when they need replacement. [img]style_emoticons/<#EMO_DIR#>/biggrin.gif[/img]

I'm surprised that the buggers last as long as they do.

My engine compartment is a souvenir shop of every track I've travelled.

The old alternator (dated 12/95) is full of everything but the gravel.

Interestingly the build date on the disco is 04/95. (143,000 km)

I think the lesson is "Watch the Tacho"
My tacho (RR) stopped working some months ago, and it was a broken alternator belt.
Then it stopped working a couple of days ago. I checked the belt, it was okay. Later the next day the car stopped with a dead battery on a country road, in the middle of road works. Not even a click from the starter. After 10min the starter solenoid clicked and a couple of minutes later the motor cranked over (new heavy duty battery with magical self recovery properties). It got me home.

It was just the brushes (in the bosch alternator), which an auto elec friend replaced free in exchange for some scanning. The brushes are soldered to the regulator which screws onto the back of the alternator. Apparently a new regulator is about $50. I say, go the wreckers and pull the reg of a Bosch alternator that looks new or recond and stick it in your tool box . I've got a bosch alternator from a corona in the shed, I think that the regulator will be coming off that, and accompanying the Range Rover on any long distance trips in the future. (apparently all the bosch regs are the same).

Sorry you had to spend so much money Mahn, I was ready to go out and get another alternator too, except for the savvy advice of a good auto elec. It seems from everyone's comments though that the tacho is the best prognosticator of a sick alternator.

I will probably pull the buggered Magnetti Marelli apart to learn something about it. I didin't realise that the Landie had something in common with Moto Guzzi and Ducati. Maybe it goes back to the Axis alliance. The Bosch won then too. :wink:

As for the money I used to own an Alfa Romeo so I start from a low base and besides I don't have the time or the resources to shop around for the best solution only the expedient one. I spent an hour on the phone shopping around for advice and the best price and used 6 hrs of 6 weeks owed annual leave doing it. [img]style_emoticons/<#EMO_DIR#>/biggrin.gif[/img]