March 1, 2015 at 8:39 pm #235615
after I got my car off the lift, the battery had gone down, so, with a little charging, I thought I would be ready, but, no.
I have gone through the testing process as listed on the tech articles, and the generator will only put out about 20 volts to start with, and, slowly goes down toward 0 volts, as I watch it. that’s even with running the rpm up
I was not able to check the brushes, and, when I tried to polarize it, it wouldn’t start turning on it’s own, but would continue to turn, somewhat slowly, but would continue to turn on it’s own.
it has a chrome cover on it, and, would be a project, on it’s own, to check the brushes.
should I go to the trouble to check it, or, just go ahead, and replace the generator.?March 1, 2015 at 9:37 pm #263443March 1, 2015 at 9:46 pm #263444
I would test the whole rig with a good battery. Also flash the field again with a good battery.
Changing to an alternator requires pulling the fan shroud and buying and mounting a new pedestal to mount the alternator on.
It may also require a different fan shroud depending on which one you currently have. The biggest advantage of an alternator is that they will charge better at low engine rpm’s. They also typically have about double the amperage rating of the stock VW generator (which I think is 30 amps).March 1, 2015 at 9:48 pm #263445
Having had antique cars with generators, I appreciate a modern alternator.
when the gen went out on my MGTDr I put in an alternator. It only took about an hour. There are some good videos on you tube if you want to do it yourself.March 1, 2015 at 10:17 pm #263446
When you switch to an alternator you MAY have to change
the fuel pump (if you have a mechanical pump) and the fuel pump shaft. The fuel pump will be at a different angle to clear the bulkier size of the alternator.
VW based 53MGTD - "MoneyPenny"
"If one thing matters, everything matters" - from the book The ShackMarch 1, 2015 at 10:54 pm #263447
Newkitman is absolutely right I already made that mistake . If you make that mistake they will take it back . Look it up on U TubeMarch 2, 2015 at 6:35 am #263448
when I flashed it, I was using a totally different battery, and, it didn’t turn very fast, and, I had to get it started.
also, it did make some slight rubbing noises that seemed to be at a certain spot.
mine has the fuel pump already removed, and, an electric one added. I can get a replacement from my local napa store, pretty cheap, and, do I really need the extra amperage?
I thought about getting some new brushes, but all this vw stuff is new to me, and, don’t know what all is involved, but, did watch some you tube videos on changing the generator out.March 2, 2015 at 7:56 pm #263449
did more testing today, it’s dead, so I just ordered a replacement for it. I won’t be driving it that much, so, I just didn’t see investing in the conversion.
gonna start the teardown, tomorrow evening.March 2, 2015 at 8:35 pm #263450
A plus with a generator , car can be pushed started if battery should go dead. Alternator not so. Alternator needs 9+ volts to work.March 3, 2015 at 7:06 am #263451
How tight is the fan belt? Generators use bushings, not bearings. If the belt is as tight as you can make it you could have worn bushings which explains the rubbing noise. Try shaking the generator pulley when you remove the belt. There should be no play in the shaft.Have you looked at the voltage regulator? That’s what turns raw generator output in the 12 – 14 volts the electrical system needs.The quickest way to learn about the Type I VW is to read “The Volkswagen For The Compleat Idiot” by John Muir. It’s available from Amazon. It will explain generators along with adjusting valves, front wheel bearings and the steering box along with everything else that doesn’t work the same way as it does on modern cars.March 3, 2015 at 8:58 am #263452
I second that. John Muir’s book is a must for any VW owner.
Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
2005 Intermeccanica Roadster
If you own a TDr and are not in the Registry, please go to http://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)March 3, 2015 at 6:06 pm #263453
I haven’t messed with the voltage regulator, due to all the generator issues. after sitting overnight, it was completely dead, with no output, so, I figure I need to start there.
you can’t regulate what you don’t have.March 3, 2015 at 9:04 pm #263454
if your car sat all night and battery is dead, I would check the regulator. The points in it could be stuck causing generator to try to run on battery voltage. If belt is loose you could see it turning, Generator will turn in both directions.March 3, 2015 at 9:27 pm #263455
George Fisher says you can’t push start a car with an alternator. Beg to differ. A year ago my battery went dead in my Porsche Cayman and I roll-started it. Neither a generator nor an alternator produces electricity until the car is running, so that is irrelevant. When you push or roll-start a car, you are just using the transmission to rotate the engine instead of the starter. If the battery has residual power, it will start. If the battery is completely stone cold dead, the car won’t start no matter whether there is a generator or alternator. Also, I’m not sure what George means in his last post. A generator does not have “points” nor does it “run on battery voltage.” A distributor has points that (maybe) could be stuck open and discharge the battery (?). A generator produces electricity, it does not “run” at all.March 4, 2015 at 6:32 am #263456
no problem with the battery, couldn’t get off the key fast enough. it runs fine, belt is in good shape, has tension, and, turns the generator as it should, just not getting anything from the generator, and, as per the tech article, I figure that the generator is done.March 4, 2015 at 8:50 am #263457
My 49 truck ran half of last summer on battery alone, until one day on the Blue Ridge Parkway it would not start from dead battery. Jumped it off, not parked on a hill. I replace the gen with an alternator. An old fashion rebuild shop is in Mt Airy. I’ll have it rebuilt someday, $60 I believe. Must be one around you.
And the gen and reg should be tested together.
Good luckMarch 4, 2015 at 3:55 pm #263458
I read somewhere that the charging system runs thru a light on the dash. The London Roadster has a blue light. The blue light comes on when you start your car but does’t start charging the battery until the light goes out. That’s the way mine works. I use an alternator.March 4, 2015 at 4:37 pm #263459
Dick, that’s about right. The generator doesn’t really “run thru” the light, but the light on the dash does tell you when your charging system is charging. If the light is on, like when the ignition key is on, but the engine isn’t running, that’s normal.
When you start the car, at any rpm above idle the light should go out. If it doesn’t, you’ve got a problem.
When you’re driving, if the light comes on, it is likely an indication that you’ve thrown the belt, which also means you’re not blowing air across the cylinders or the oil cooler. You would need to shut off the engine immediately and hope for the best.
I think, but am not sure, that the light is supposed to be red. The Hi beam light is the only one I have that is blue.March 4, 2015 at 6:01 pm #263460
I’ve read that the warning light also completed the excitation circuit in the regulator. If the bulb is burned out the generator will not charge.
Not sure if its the same with an alternator. I’ll research that tonight while up here in DC. Might as well as the TV in the room is inop. 🙁
VW based 53MGTD - "MoneyPenny"
"If one thing matters, everything matters" - from the book The ShackMarch 4, 2015 at 6:08 pm #263461
Allen, I think that you’ll find there’s no difference with the alternator regarding excitation being required. Alternators still use regulators – it’s just that the regulator is built in for VWs, and not external.
Early FF TDr on 69 VW pan
Slowly coming back from the ashes...March 4, 2015 at 6:44 pm #263462
I heard the same thing about the light completing the circuit , mine will not charge the battery until the light goes out and I am using an alternator.March 4, 2015 at 7:09 pm #263463
mine doesn’t have a light, it has an ammeter.March 4, 2015 at 7:16 pm #263464
Ed, Many of our cars have ammeters. But most also have a generator light. See “Rob and Daves VW resource” page on the internet. It is a good reference point in addition to the Idiot book. Some do require that this light be hooked up to allow the generator to charge. Could this be your problem???
As I said above, the light is an early warning indicator of a thrown belt and impending doom due to lack of cooling air.March 4, 2015 at 8:15 pm #263465
the only lights I have are the turn signal indicators.
so does this mean that the tech article isn’t totally correct?
Disconnect the generator from the regulator (probably easiest to simply take the wires off the generator).
Connect a jumper from DF on the generator to the generator frame. Now run the engine and measure the voltage from ground to D+ on the generator.
As you increase the engine speed, the voltage should jump up to +35 volts or so (@3000 RPM).
If it passes this test, the generator is good.March 4, 2015 at 8:53 pm #263466
What part of what tech article? Be advised that these cars are not necessarily pure VW. So, your generator or alternator and voltage regulator and requirement for a generator light or not may be different, depending on your configuration. …..or, I hesitate to call any advice by another wrong.
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