[T3] Arcing

Jim Adney jadney at VWType3.org
Sat Nov 14 10:12:35 PST 2015


On 14 Nov 2015 at 17:51, Daniel K. Du Vall wrote:

> Question should I see a lot of arcing going on in the viewports of the
> generator? It seems to be allot more that I would have expected. I am
> trying to trace down some issues so want to rule this out. Also what
> should I see voltage wise without any load see about 12 to 13 off idle
> somehow I think I should see at least 14 and at least 13 with a load
> at cruising speeds. 

It's normal to see a little arcing, but not a lot. Yes, that's very 
subjective, but I don't know any better way of putting it. If there's 
a lot of arcing, the commutator has worn out of round and should be 
turned on a lathe to make it round again. Try to find a local shop 
that can do this, and make it clear that they should take off a 
minimal amount of copper to clean up the commutator. A good auto 
electric shop should also be able to clean out the mica in the 
grooves properly, but I've done that by hand with a razor knife or a 
thin hacksaw blade. Unfortunately, good local auto electric shops are 
becoming scarce.

I can do this for you if you want to mail me just the armature. It's 
a pain, however, to pack carefully and mail. You can send the whole 
generator, but that's even more pain. Careful packing for these is a 
MUST.

Measure the voltage at the battery after the engine has warmed up 
after a drive. Note that the voltage rises as the rpms go up. The 
voltage rises and then stops rising. That's what I call the plateau. 
That's where the system voltage has actually come into regulation. 
That's the ONLY voltage that's relevant. The voltage at idle or just 
off idle is irrelevant.

The plateau (regulated) voltage should be 14.1-14.4 V. As the voltage 
regulators wear this voltage declines. Low system voltage makes the 
FI run rich. You won't notice any change down to about 13.5 V. Below 
13 V the car will become annoying to drive. I recommend replacing the 
VR with a Bosch 30-019 if the plateau (regulated) is 13.5 V or lower.

I have Bosch 30-019s in stock if you can't find one locally.

I'm working on a microcontroller version of my own design, but that's 
still a work in progress, Maybe by mid-2016....

-- 
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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