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Marelli Alternator


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My 200tdi is fitted with a Marelli Alternator (45amp IIRC), this appears to be original as it is date marked 1992.

Although I changed the brush/diode pack it still only intermittently extinguishes the charge light when started, charge light goes out and light from headlamps increases once engine speed is increased.

Once charge light is out it remains so and headlights remain bright, even on restarting within an hour or two. All wiring checks out and charge voltage is correct.

One thing noted when I changed the brushes was the brush tracks are worn deep (about 4mm) :unsure: .

So suggestions please…. do I buy a new unit, if so what - would only need to be 65-70amp max.

Thanks

Rod

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EPC tells me that the optional Alt on a Defender 200Tdi was a 65amp & standard fit was a 45amp, I'm sure mine came with a 65amp fitted from the factory. find a 65 or better a 100amp from a air con fitted Disco 300Tdi, but be sure to upgrade the wiring.

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Thanks Andy/Western.

I assume that the consensus of opinion is it’s knackered.

So I have more questions: -

1) Do I need to alter a 300tdi unit to fit it to a 200tdi, i.e. rotate the cases etc?

2) Are the connector plugs the same?

3) Should I stick with Marelli or are Lucas any good?

4) Do I just need to up-rate the main cable to the battery?

Thanks again

Rod

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Thanks Andy/Western.

I assume that the consensus of opinion is it’s knackered.

So I have more questions: -

1) Do I need to alter a 300tdi unit to fit it to a 200tdi, i.e. rotate the cases etc?

2) Are the connector plugs the same?

3) Should I stick with Marelli or are Lucas any good?

4) Do I just need to up-rate the main cable to the battery?

Thanks again

Rod

Probably needs a overhaul & a new slip ring [the bit the brushes run on]

1, IIRC when my 100amp was fitted we had to realign the rear of the casing to set the mounting lugs correctly

2, connectors are different marrelli uses ring terminals on end of the cables [your existing is probably like that already]

3, Marrelli are better in my opinion, there's another thread about alts on here with more info re- Lucas alts

4, IIRC mine was uprated to battery & starter.

hth :D

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i prefered the lucas alt for one reason. you can remove the brushpack in about 5mins. ive have a few times when mud has caused the brushes to stick 'in' resulting in no charge, its a 10min fix on a lucas but about an hour on the MM.

i believe my alt was a 300tdi one originally, i just fitted the old pulley (few goes with washers in different places to line it up) & away you go. oh & cut the lucas plug off & used ring terminals.

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My 200tdi is fitted with a Marelli Alternator (45amp IIRC), this appears to be original as it is date marked 1992.

Although I changed the brush/diode pack it still only intermittently extinguishes the charge light when started, charge light goes out and light from headlamps increases once engine speed is increased.

Once charge light is out it remains so and headlights remain bright, even on restarting within an hour or two. All wiring checks out and charge voltage is correct.

One thing noted when I changed the brushes was the brush tracks are worn deep (about 4mm) :unsure: .

So suggestions please…. do I buy a new unit, if so what - would only need to be 65-70amp max.

Thanks

Rod

If the slip rings are that badly grooved the new brushes won't be making proper contact, hence still low output, although it may improve as they bed in. :unsure:

You really are better off with a replacement unit as the bearings will probably be on the way out as well. The bottom one which isn't sealed is probaly full of carbon from the old brushes....

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