240 MF built in GB alternator question

[TheEquineFencer]

I've got my neighbor's 240 MF tractor here in the shop, the alternator is not charging. I washed the oil and grease off/out as best I can so far. My question is how to test the wiring to it and the alternator itself. I think it's a Lucas Alt from looking at the MF website. This thing has a FEL on it so it's a bit of a pain to work around that. I'm guessing the brushes might be stuck from the grease. It looks like the regulator is bolted to the rear of the Alt.

I'm going to run over to the parts house and get some cleaner and try washing the guts out of it to see if I can get some more **** washed out and see if the brushes might be stuck before I try to take it off. I'd like to do some checks before I condemn the Alt and then find out it's a broken wire going to it. A wiring diagram would be nice.

Thanks in advance for any help.

 

[LS6 Tommy]

Of course it doesn't charge. It's a Lucas...


Sorry, that's no help.

Tommy

 

[theoldwizard1]

Alternators are pretty simple.

• If it has an external regulator there should be an external field connection. Disconnect the field lead from the regulator and jump it to B+. At high idle you should have >12v. If you do, it is a bad regulator.
• With the key off, check the field winding for open. They should be low resistance to ground.
• Further testing will have to be done off of the vehicle and on the inside of the alternator.
• Carefully remove the back. Make sure the brushes and springs don't go flying.
• Inspect the slip ring contacts. If they look bad clean then up with fine sandpaper.
• There should be 3 wires coming off the stator. Check for short to ground from each. Check resistance between each pair. It should be equal.
• You can check the diodes, but is difficult to determine the anode and cathode of each because the way they are mounted in heat spreader bracket.

 

[gungatim]

not familiar with that exact setup but have worked on older lucas alternators on my british cars. the diode trio was a common failure point, the pins of the diodes would pull right out...probably not applicable to that one but you could at least run the motor and see if you are getting ac out of it instead of dc...

 

[bobmulry]

Of course it doesn't charge. It's a Lucas...


Sorry, that's no help.

Tommy

I thought that Lucas was the prince of darkness?????????????????

 

[TheEquineFencer]

The rotor is eat up and the brush block has a stuck brush. I broke part of what was left of one of the brushes trying to get it to move free.

Now to try and find an alternator on Saturday to go back on it...

I wonder how I can rewire it to use a GM alternator so the fails to charge light would work?

 

[justsam]

The rotor is eat up and the brush block has a stuck brush. I broke part of what was left of one of the brushes trying to get it to move free.

Now to try and find an alternator on Saturday to go back on it...

I wonder how I can rewire it to use a GM alternator so the fails to charge light would work?

Not sure how desperate you are to get it rolling again, but I suspect you have identified the root cause as the brushes. Clean up the holder get some replacement brushes for some generic Lucas alternator that are close to being right and file to fit.

 

[Fishplate]

Delco or Bosch alternators are sometimes used as direct Lucas replacements in some British cars. Dunno about your wire arrangement and how that might work - doesn't look like the Lucar connector I'm used to...

 

[TheEquineFencer]

Delco or Bosch alternators are sometimes used as direct Lucas replacements in some British cars. Dunno about your wire arrangement and how that might work - doesn't look like the Lucar connector I'm used to...

Actually the wire plug on the back is the same on a Mercedes that comes with a Lucas. I found another "picker" like myself that has a brand new one that he got new in the box with a "junk" Mercedes he got from a "pick." But the front flanges for mounting are in the wrong location and the brush block in his alternator is bigger, it would almost fit. I've spent at least two hours at Advance trying to find an alternator;Lucas, that would fit to no avail. The OEM part number is a 3405390M1. I wish I could find an interchange that would convert it to a part number NAPA or Advance could find.

I also tried finding a GM that would or could be made to fit back in it's place with an internal regulator to no avail. The two mounting ears on the front are 180* apart.

 

[TheEquineFencer]

I thought that Lucas was the prince of darkness?????????????????

I spoke to a BMW biker buddy of mine, he said the same thing. "Lucas was the prince of darkness" He said every bike built in the UK and probably Europe has a Lucas alternator and at any given time they will quit when you're in the middle of nowhere. All three of his have put him down.

 

[nehog]

...

I wonder how I can rewire it to use a GM alternator so the fails to charge light would work?

Yes, you can do that. A CS-144 style might work.

 

[TheEquineFencer]

I think the pulley is an issue and then the mounting brackets. I found a **** load of that style, but they had serpentine belt pulleys. I'm looking something quick and easy.

I'm looking for the parts besides going to the MF dealer right now.