Alternator over voltage

Does sound like a bad regulator to me. You might double check the readings with a portable digital meter. Finding a new regulator may be challenging...

Speedy Jim

I agree...., had a similar problem on my '74 sunbug late last year.

It started gradually, but within a week even a short drive would result in clouds of sulphuric "smoke" from under the seat => very dangerous. I put a VOM across the battery and found I was literally boiling the battery at 22+ V. Needless to say, I decided it was time to winterize her.

Now I have a new battery, a V meter in the dash, and a new regulator. In my case, it was the external cigarette box sized Motorola regulator under the back seat (left side). As Jim mentioned => it was very difficult to find a replacement. I finally found a used one (works great so far) on eBay.

Since the Motorola alternator was OK, I decided to go that route rather than invest in a new alternator / regulator pair.

Good luck.

On Tue, 11 May 2004 01:22:24 GMT, Canuck V'dubber aka Michael Zeeb ran around screaming and yelling:

isent my 74 to the scrapper with one still mounted under the rear seat(i had bypassed it and installed a bosch internally regulated alt)....i had two "extras" in the basement i tossed in the car(along with a bunch of other parts and another bug body)...i should have kept them....

Aaarrrrggh ! You have no idea how long I looked for one!

I do have a spare now; a NOS ATLAS #668 fresh in the original box. I'm saving it for when the used Motorola gives out.

One man's trash......

I wonder what other treasures have found their way to the crusher?

On Tue, 11 May 2004 02:29:43 GMT, Canuck V'dubber aka Michael Zeeb ran around screaming and yelling:

heck i *tried* to give the thing away...but too many people just switch over to the internally regulated alts.....i have thrown away lots of good parts over the years....when that bug went to the scrapper it was *loaded* with parts....engine cases, trannies, engine parts, etc....i was "spring cleaning"....i threw out all the parts because " i don't use "stock" parts"....right after that i found myself looking for an engine......it sucked as i had thrown away what was probably five or six complete engines(if assembled..) JT

I see a lot of part suppliers carry external regulators for alternators.

I see a lot of part suppliers carry external regulators for alternators.

I checked with all these places and more for the Motorola part last year => no luck.

I th>Speedy Jim wrote:

Ok. It was Motorola version you were talking about. Is that US only=20 or installed also in Europe?

Ok. It was Motorola version you were talking about. Is that US only or installed also in Europe?

On Tue, 11 May 2004 15:00:47 GMT, Canuck V'dubber aka Michael Zeeb ran around screaming and yelling:

Joey was throwing out all vw stuff at one time....decided i didn't need all those "pos car parts"...hehe....but really i did... JT

It's not okay, and you want to fix it. The problem is what to fix.

It could be a bad meter, so double check the reading with a good DVM.

It could just be a bad regulator, but those usually wind down in voltage as they age. Is this a Bosch system with the regulator in a metal box about the size of a squat pack of cigarettes? If so, those are still available, or at least I have some.

It could be a bad ground, so make some similar measurements in other places: across the alternator, across the battery, etc. Make sure that there is no measurable resistance between the grounds of the alternator, the battery, or the regulator.

It could also be that the battery is just about boiled dry and this is the result. Check the water level in each cell.

Yes, this indicates that you charging system is working. Just not quite right (maybe.)

Yes, overvoltage can boil the battery and burn out bulbs, etc.

----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

-----------------------------------------------

Thanks for everyone's input.

I sincerely hope it'd not the battery at fault!! it's brand new. Having said that, at idle (ie lowest alt output), the gauge reads around 12 volts, and the engine cranks fine, suggesting the battery is OK.

I will, of course, check the voltage at various places with a DVM, but my gut feeling is that the reg is bad (it was a cheap swapmeet find!)

Thanks again,

Paul

OK, I did some more research yesterday evening. The battery is fine. Using the DVM, I got 12 volts @ idle and 20+ volts (!!) @ 2500rpm at the alternator, the battery terminals and the voltmeter terminal in the dash - so no iffy earth connections.

So, I think the reg is shot - it just isn't regulating the alternator output at all - and the voltmeter has to go too - it can't handle a reading above 15 volts, regardless of input voltage.

I should be able to get a regulator from my local VW spares shop (about £17) and the voltmeter is the only non VDO gauge on the dash, so I've been meaning to change it for a while (but you - if it ain't broke....except it is now!!).

cheers

Paul