Thread: Marelli alternators ok?

Well yes It was a bit harsh but you are not the first. Anyone with a lot of experience with Land Rovers knows that the alternator is probably the worst performing part of the earlier RRCs and discos anyway. Funnily enough the starters seem to be quite good.

I know Marelli took over Lucas. That is why they changed the branding to Magneti Marelli. However the alternators are just a progression of Lucas designs up to the 92-93 series anyway.

They are renowned for their poor rating compared to say Bosch.

Every Auto electrician I have spoken to reckons they are rubbish, mainly because they claim that there amp rating is a "cold" rating rather than "hot" so a 65 amp alternator only puts out 65 amps while cold.

Add this to underspeccing by land Rover and adding driving lights and high use of aircon in Australia and it is a recipe for failure. I can remember one hot wet night driving along and watching my voltage fall to about 12.9 over an hour with driving lights , headlights,wipers and aircon on.

The final nail is that the parts are not readily available in Australia and are quite expensive even when imported from UK even if you are willing to wait the time to get them.

Regards Philip A

Funny you should mention driving with Driving Lights, Air Con on etc.

About 15 years ago I was driving from Katherine to Nhulunbuy in Arnhem Land on a dirt road that covered 788km's including 4 Crocodile infested river crossings.
I had driven from Mt Isa that day and planned to have stayed in Katherine for the night. But like an old horse dashing to get home I decided to put the kids in the back to sleep and the Mrs and I took off to do the drive through the night.
I was driving an old 72 model Range Rover V8 and had to run the fan AND the Air Con just to pressurize the car to try and stop the dust from blowing in from the back. As well, I had 2 100 watt Driving Lights on the entire time.
Anyway, around 2am I came over a small hill and headed down to "what I thought" was a small stream. Instead, it was a wide river!
I came down the hill and hit the river at about 90kph. The motor died instantly and everything just stopped and we were overcome with silence!
The kids all woke up and asked, "Where are we Dad?"
"In a river" I said.
I went to restart the motor and all I got was a "click" "click" "click" from a starter motor that was weakly being powered by a very discharged battery.
The water was just up to the height of the bonnet and was slowly seeping into the cabin, of course until I opened the door, then it poured in!
I was tired, and kind of mentally stressed as I had no idea of what I could do to get the car restarted.
It was about then that I realised that I was standing in a Crocodile infested river without a single idea of what I could do to get my car and family out of it!
Then, like a flash from heaven, I remembered seeing an old crank handle that was always just sitting there, clipped to the rear wall of the car just behind the spare tyre and jack.
I opened up the rear hatch and searched around until I could feel the crank handle.
I finally found it resting under all the wet costumes and dirty underwear, which were also wet by this time.
I had no idea if the motor would start with a crank handle, after all, it WAS a V8!
Anyway, I asked my wife to get into the drivers seat with instructions "that IF this thing DOES start, floor it and run over me if necessary, just get this thing to the other side!"
Well, I then tried to put the crank handle into the hole which started in the centre of the front bumper bar. It was really difficult actually!
It was hard because I had to actually hold my breath and put my head under the water just so I could reach the bumper bar with my hand to feel for the hole.
I eventually got the crank handle into the hole and started to crank the V8 engine with this little crank handle under water!
Soon enough, she fired up with a roar and my wife nearly drove over me. Literally!
All that really DID happen, and all because the old Rangie had too small an alternator to run Driving Lights, Fan, and Aircon all at the same time.
But for some reason, only known to the Pommies, it also had a Crank Handle!

Originally Posted by Peppercorn

[snip]
But for some reason, only known to the Pommies, it also had a Crank Handle!

Of course there was a reason, the same engineer that was made to spec a 45 amp alternator by the bean counters also reasoned it wasn't up to the job so specced a crank handle as well

Yeah, I remember my 81 in Saudi. I pulled the noisy bearings out of the Lucas and they were made in wait for it Yugoslavia.

Now Czechoslovakia would be have been OK , because the Czechs do not bounce and they made most of Mr Hitlers tanks at Brno which were very good.
.
BUT I ask you Yugoslavia? Not exactly a great reputation for quality then, but probably the cheapest to put in a bloody luxury priced car.
Regards Philip A

One advantage of Marelli is I think they stiill make the largest 4 leg alternator (120 amp) that will fit in V8 Disco's & RR's and <$400. I put one in when the OEM toy died over 10 years ago and it is still going strong.

I still have the original 65amp MM alternator on the Defender and while it's had a precautionary bearing change (and the stupid little unsealed needle roller in the back greased multiple times) it's still the original brushes and diode pack.
Current km on the car is 265,000km. The 100amp one is altogether a better alternator than the 65amp, and at least rear bearing is replaceable and sealed.

[edit] I think the MM100 amp version to suit a Tdi is sold as a Denso too.