red-hot dynamo

[pointer]

We recently got an David Brown 995 "project". Still wouldn't start after sorting engine so got new battery. Engine turns over well now, but (what I think is) the dynamo is getting very hot - visibly red-hot at the connection and sending out sparks.
Why is this happening, how do we sort it, and is this why it won't start?
We know only the most basic mechanics - this is a big learning curve! Thanks

 

[phillipe]

sorry thought it was a different thread

 

[Selectamatic]

No idea, but what a porn name!

 

[Mursal]

Probably not charging?
Have you got any warning lights or meters to look at?

For safety, disconnect the battery when its not running until you find the cause. The negative terminal market with a minus sign - is the safest to remove. You cant get a shock form the battery but dont connect the positive (marked +) to the steel body work by accident.
It's probably the regulator (big black box with D, F. E and B terminals on it) that's at fault. .
Reconnect the battery and with the engine stopped If you disconnect the large wire on the Dynamo see can you see sparks or the dynamo trying to turn? If so you need a regulator.Might be an idea to leave it disconnected, but dont let the connection touch the steel work, cover it with tape or plastic.

If you are not confident working on the wiring ask someone to help as it can be mind blowing and cause more harm.

Let us know how you get on ..............

Control box = Regulator

 

[mushnt grummmble]

Is battery connected properly?


Some were positive earth!!!

 

[Mursal]

Yes that would explain it .........................

 

[pointer]

Thanks for help guys, yes I do at least know the negative sign! But "some were positive earth" is getting too technical for me! But we'll have a go at Mursal's suggestion, thanks.

 

[mushnt grummmble]

Thanks for help guys, yes I do at least know the negative sign! But "some were positive earth" is getting too technical for me! But we'll have a go at Mursal's suggestion, thanks.

Check it out
Follow the plus wire see where it goes

The dynamos also need polarising

 

[Mursal]

Just check that you put the new battery in the same way the old one came out, that's what @mushnt grummmble meant.
If the negative was connected to the bodywork, or the positive?

 

[mushnt grummmble]

Just check that you put the new battery in the same way the old one came out, that's what @mushnt grummmble meant.
If the negative was connected to the bodywork, or the positive?

I ment some old kit could be positive earth...

 

[Mursal]

Yes I know, I hadn't thought of that when I replied to the question.
And it may well be the cause of the heat, dynamo trying to turn as a motor.

 

[Mursal]

@pointer
Just keep in mind that the dynamo system of charging the battery isn't as straight forward as modern alternators, so give yourself a bit of time to have a bit of a head scratch about it .............

 

[mushnt grummmble]

Yes I know, I hadn't thought of that when I replied to the question.
And it may well be the cause of the heat, dynamo trying to turn as a motor.

Take the fan belt off to see that

 

[Bury the Trash]

how about fit an alternator now.

 

[mushnt grummmble]

how about fit an alternator now.

That wouls need mild rewire of the charging circuit

 

[Mursal]

Well dont spend a fortune on the dynamo or regulator or wiring loom, an alternator would be more practical, but not original, if its for vintage.

 

[Kiwi Pete]

At a guess, (I don't know much about the 995) but most generator vehicles were +ground
They could be polarized the other way if you gave the leads a touch the wrong way which would then make it a -ground like most all modern gear with an alternator.
Then you could put in a fancy wireless without having to completely insulate it from the vehicle chassis.
At a guess this tractor may have the battery around the right way, but the dynamo/generator isn't polarised the correct way- or a dud regulator as above.
Whip off the belt and see if the pulley turns when you connect the battery, and see which way it turns if so.
That's about where I call in the experts as sometimes they are much cheaper than stuffing good parts

 

[Dirt!croston]

It should be positive earth unless someone has changed it, which is unlikely, its probably toast now.

 

[Exfarmer]

I would think its toast, a change to an alternator is the best bet , unless you want to keep it authentic. I have done several in the past. When fitting an alternator, be very careful to not over tighten the bolts on the brackets, ensure they are washered to make a snug fit first, or you will break the delicate frame on the alternator

 

[REStracTORATION]

If this was mine
1st job remove belt hook up jump leads to check dynamo spins etc this just tells you the internals are functioning in the way they should.
Then swap the battery to negative earth this is better as poss earth seems to create furring of connectors
Then Polarise the dynamo remove both wires off dynamo take a jump wire from the live side off the starter and touch it to f terminal the smaller one of the 2 get it sparking or exciting as it's known.
Refit both wires then run up and check charge

Also worth noteing the control box is it isolated to the rubbers perish around the fixing points if it's a China one just chuck it in the bin if it's some age and refit a new one
Check the wires are hooked up correctly and no wires have rubbed through or broken.
It's a simple system and easy to work on