[T3] Car Won't Start (no subject)

Jim Adney jadney at vwtype3.org
Wed Oct 29 15:20:32 PDT 2014


On 29 Oct 2014 at 17:46, J. Jonik wrote:

> Car has started...mysteriously...just after a battery load and
> whatever other test the auto shop did.  It passed easily.   Test took
> 40 minutes...so maybe it got charged too?  Forgot to ask.     But my
> tester, before their test(s), showed all cells at the top of the
> "good" range. 

There's really no mystery here at all. From your symptoms, it was 
clear that you had a bad connection somewhere in the starter circuit. 
When you removed and replaced the battery you opened and re-made 2 
connections, at the 2 battery posts. The bad connection must have 
been at one of them.

Poor connections here are common. Since the posts are tapered, people 
tend to not get the clamps all the way down on the post, so the 
clamps keep getting smaller and smaller over time, until eventually 
the clamp closes on itself and isn't really grabbing the post any 
more. This is a situation that will work sometimes but not always.

It doesn't take much resistance to make this circuit fail. A tenth of 
an Ohm is more than enough. That amount of resistance wouldn't even 
be noticed in most other circuits.

The solution is to spread the clamps every time you install them, so 
that they slip ALL the way down over the post. When properly 
connected, the post will stick up maybe 1/16" above the top of the 
clamp.

> The generator light, it turns out, stayed on when running because a
> ground wire at Voltage Regulator was kind of hidden, and unattached. 

That ground wire is a good thing, but it's really only necessary once 
the mounting screws and sheet metal for the VR have gotten rusty. On 
the old mechanical style of VR there is a separate place to install 
that wire, although at the factory they just put that wire under one 
of the mounting screws. Once things get rusty, it's a good idea to 
move that wire to the special place for it on the VR frame.

I don't think the modern solid state VR has the attachment point for 
that ground wire, but I could be wrong about that. If it's not there, 
that's a flaw in the new design.

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