Dynamo depression. Idea shortage.

[starbiscuit]

Hello all,

After a large list of issues left me by the PO, I have just got the engine and gearbox back into the bus.
It's taken ages because I get so little time on it and only in short bursts.

I checked oil pressure and fuel delivery, connected ignition to coil and after a few seconds cranking it burst into life.

Brilliant

Running a bit lumpy, but running. Having made no effort than best guess at distributor timing and carb mixture, that was a result.

Except that the generator light won't go out when the engine is running. Which is really depressing
The light comes on bright with ignition ON and stays on bright with engine running. At low, medium and high rpm the light stays the same.

I am sure that it was OK before I pulled the engine.

However, the original regulator was fried; the resistance wire on the bottom was gone. I found this when the engine was out, so I had replaced it with a spare HUCO electro-mechanical one.
And the wiring between the generator and the regulator was missing the ground wire which had melted at some point, so I fitted a new harness section.

I have found quite a lot of advice here on EB about generator testing and here's what I have tried:

Battery is 12.6V with engine off, and exactly the same with engine running.
The wire from the dash G light to terminal 61 is not broken or shorted and is connected correctly at the regulator.
The D+ and DF wires are new and correctly connected.
The wire to the battery from regulator B+ is correctly connected.
Fan belt tension is fine. Fan belt was replaced recently, but not since engine-out.

I disconnected the generator wiring from the regulator and removed the fan belt.
With DF grounded and D+ flashed momentarily to battery, the generator spins.
With DF grounded and voltmeter on D+, I spun it with an electric drill and it made barely 20V at fairly high rpm.
Some folk on youtube seem to get 80-100V doing this.
Although the brushes looked plenty long enough, I replaced them. And tried to clean the armature.
But no change; G light still on.

I have tried a new Bosch solid-state regulator in place of the HUCO one, but no change; light still on.

Now I have completely run out of ideas.
Is it possible that the original fried regulator has also damaged the generator?
Or the generator is faulty and fried the regulator?

Is the generator dead?
What else can I test?
Is it possible to change the generator without removing the engine?
Is it worthwhile to fit an alternator kit, and can that be done with the engine in the bus?

I think if I have to take the engine out again so soon, I'll be made to wear concrete boots and count fish.

Thanks for reading

 

[Bluesnailman]

i had a bad connection on the starter motor.... where the main feed comes to starter, then goes forward to the dashboard. It made the dash light come on even though everything else seemed to be working ok

Mine was intermittent, but not dissimilar. However, you've got much further than I did, checking voltages etc so can't comment beyond my experience

 

[Trikky2]

This should help http://www.speedyjim.net/htm/gen.htm" onclick="window.open(this.href);return false;

 

[StuF]

Sounds like your generator is the issue as the voltage across the battery doesn't increase when the engine is running - mine goes from 12.4 up to 14.6 although I do have an alternator conversion

Do you have the opportunity to install an alternator conversion? It's a worthwhile improvement especially if you decide to run a leisure battery and split charge system in the future

 

[Peter Good]

Have you performed the Polarizing as described by Speedy Jim? Very often when a regulator goes, it destroys the residual magnetism in the dynamo. Restarting can be a bit of a pain but easier than removing the dynamo.
Peter Good

 

[starbiscuit]

Yes, I tried the re-polarising before I tried changing the brushes.

In last-ditch desperation, I took off the generator wiring and the regulator and cleaned all the contacts with emery paper and then petrol.
I cleaned up the regulator mounting screw holes on the side of the wheel arch.
And I squeezed up all the spade connectors.

I put it all back together and after a brief flicker, the G light now goes out and stays out at idle.

Knowing that the output voltage is still quite low, I don't know how long this situation will last, or if it will sustain headlights *and* wipers, but it's working for now, which is a relief

Meanwhile I have ordered an alternator kit and hope to do a planned swap rather than an emergency one.

Thanks all for the advice.

 

[StuF]

Result 8)