Lucas 3M100 & 2M100 starters...

Hi All,

I've got dodgy starter motor. After messing about with the usual tests in the car for a few days, I pulled it out today and it quickly became obvious there was a problem. Thankfully I have a spare which seems to run pretty well but it's a slightly different Lucas model and I wondered if it was compatible.

The old broken one is a Lucas 3M100 - 025701B43
The good one is a Lucas 2M100 - 25654E4174

They look almost identical except the gear wheels are slightly different. Picture attached.

Do you think the Lucas 2M100 will be okay to use?
The engine is a late 80's Range Rover Discovery v8

Many thanks,
Stephen

Stephen Thomas said:

Hi All,

I've got dodgy starter motor. After messing about with the usual tests in the car for a few days, I pulled it out today and it quickly became obvious there was a problem. Thankfully I have a spare which seems to run pretty well but it's a slightly different Lucas model and I wondered if it was compatible.

The old broken one is a Lucas 3M100 - 025701B43
The good one is a Lucas 2M100 - 25654E4174

They look almost identical except the gear wheels are slightly different. Picture attached.

Do you think the Lucas 2M100 will be okay to use?
The engine is a late 80's Range Rover Discovery v8

Many thanks,
Stephen

Click to expand...

I doubt if those are going to be a straight swap. The gears look different diameters, and different numbers of teeth.
You might be able to use the 2M100 by changing the gear that engages with the ring gear on the flywheel over from one to the other.

Can you be more specific about the fault with the old one? Does it appear to be the motor itself, the solenoid, or the gear mechanism.

I think those are very repairable and serviceable. Not sure where you are in London?
But I have had very good results with Sahib's Auto Electrical, on Norbreck Parade, by the Hanger Lane Gyratory system.
They usually have exchange units in stock, if not, will sometimes rebuild while you wait, and are reasonably priced.

Stephen Thomas said:

Hi All,

I've got dodgy starter motor. After messing about with the usual tests in the car for a few days, I pulled it out today and it quickly became obvious there was a problem. Thankfully I have a spare which seems to run pretty well but it's a slightly different Lucas model and I wondered if it was compatible.

The old broken one is a Lucas 3M100 - 025701B43
The good one is a Lucas 2M100 - 25654E4174

They look almost identical except the gear wheels are slightly different. Picture attached.

Do you think the Lucas 2M100 will be okay to use?
The engine is a late 80's Range Rover Discovery v8

Many thanks,
Stephen

Click to expand...

The most common fault with the actual motor is the brushes. Quick internet search reveals they are available, at the cost of £4.99, probably plus postage.

https://www.autoelectricalspares.co...-brush-set-replaces-lucas-60600196-2643-p.asp

Thank you...
I had intended to get the old one refurbed at some point. Hanger Lane is very close, I'm in North London, so this sounds like a good option.
The problem I've got with it is that it doesn't push the gear out, when I tested it on the bench. It spins and the gear moves little but not much, so it isn't engaging the fly wheel and not spinning the motor.
I'm not sure if that is a solenoid or starter issue.

The distance from flange to gear looks vastly different, I dont think it will even reach your flywheel

Stephen Thomas said:

Thank you...
I had intended to get the old one refurbed at some point. Hanger Lane is very close, I'm in North London, so this sounds like a good option.
The problem I've got with it is that it doesn't push the gear out, when I tested it on the bench. It spins and the gear moves little but not much, so it isn't engaging the fly wheel and not spinning the motor.
I'm not sure if that is a solenoid or starter issue.

Click to expand...

I think that is an issue with the mechanism that pushes the gear out, sometimes known as a Bendix.
You can fix that yourself, by cleaning the mechanism with spray cleaner, and lubricating it.
It might be worth having a look at the brushes at the same time, if they are worn, it is a simple job to change them.

But remember Sahib's if you get further issues with rotating electrics, I have found them to be very helpful in the past.

thx guys much appreciated
- Stephen