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Re: [T3] Hrmmm, a new Predicament


On 31 Jul 2003 at 13:57, Kurt Nolte wrote:

> Ok... some new information for you guys to chew over. We went out and
> did the tests that Mr. Adney's FAQ listed, with some HIGHLY unusual
> results. About the only really good thing that came out of it was that
> I now know that the indicator light isn't shorting. When I did the
> first test, I initially got a reading of 12.35v between the fusebox and
> ground. This value dipped to 11.4v while I was starting the car, but
> it quickly jumped back to 12.3 once the engine was running. Giving it a
> little gas, the reading rose to a max of 12.8v after I pushed the
> pedal down about a third of the way. After shutting off the engine, my
> voltmeter only registered 5v. I removed the connections and reapplied
> them, just to make sure, and got readings anywhere from a min of 2.3v
> to 8.1 volts. 

Yes, this DOES sound confusing. I wonder if you had the voltmeter set to read 
AC instead of DC? Otherwise you have some bad connections either in your meter, 
your meter leads, or in the car. Where were your leads connected?  

> Somewhat perplexed and confused by these levels, we moved on to the
> generator test. This one was the real kicker; we performed the test
> twice, about five minutes apart. Each time, the voltmeter only read
> 1.2v EACH TIME! When revved, the reading only reached 1.27v! The screw
> was in place, and the brushes are brand new. Stamped on the generator
> housing is "rebuilt NY22." A final bit of information; the generator was
> HOT. Extremely so. It seems odd, seeing as how the engine had only been
> run maybe 5 minutes in the past hour and a half. 

So was this the test where you disconnect the wires at the generator, short the 
DF term to ground, and then rev the engine while measuring the voltage between 
D+ and ground?

If so, then your generator is dead. You can try repolarizing it (does the FAQ 
cover that?) or just take it out and take it to an automotive electric shop for 
diagnosis or repair.

If it really got hot that quickly, then the field windings may be cooked and 
this may be the problem. Has it been installed correctly: little hash mark on 
top facing straight up? If not, it didn't get the proper cooling and cooked 
itself until it shorted out.

If you go for a rebuilt, I recommend that you buy a genuine Bosch rebuild or a 
rebuild from a local shop that you trust. I DON'T like Lucas rebuilds of Bosch 
generators.

I have good used generators here, too, but it is probably more cost effective 
to see if you can buy one locally. Keep me in mind if this turns out to be 
difficult.

BTW, you should repeat ALL the tests once you install the rebuilt generator. It 
is important that you make sure that it's working correctly or you may damage 
other things, possibly even your new generator.

-- 
*******************************
Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA
*******************************

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