Date: Wed, 25 Jun 2008 12:43:02 -0700
Reply-To: Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM>
Subject: Re: electrical testing proceedure question..Not van specific,
but..
In-Reply-To: <000501c8d6ef$8f443980$4001a8c0@gateway.2wire.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
hi don,
the only way I ever test charging voltage ( which is what you are really
interested in ) is at the battery terminals with the engine running, and
the alternator charging of course.
12.7 Volts is Perfect for the battery's 'resting voltage'
............engine off in other words. That is Ideal.
13.4 si good............or at least 'ok' for a charging voltage.
vanagons often run at 13.8. I conisider that acceptable but lowish.
I like to see more in the 14's.,.........with a max ok of 14.5.
no, unless you have some other symtem also with the alternator , don't
take it to a shop if it's charging at 13.4.
not normally anyway.
you could undo the belt and spin the alt. to check the bearings for play
and roughness.
on 2.1 waterboxer vanagons I often find alternator bearing play that
seems a bit too much.
it should turn perfectly smoothly with no noise, roughness, or play in
the shaft, end wise or side-play.
so back up and start all over.
WHAT IS THE REAL SYMPTOM ??
you say 'won't keep starting'
sorry to be picky but are we talking won't crank strongly ? or won't
crank at all ?
or cranks fine but won't fire up ?
I have never know any person in 5,000 times of hearing 'she won't start'
and have them say if it's that it cranks fine and wont' fire up, or it
won't crank on the starter at all, or strongly enough.
so.............what is the REAL symptom. ? You comment 'won't keep
starting' makes me think of a key-off current drain.
the very simplest test for that is disconnnet the battery when the truck
is not in use.
if it always crnaks fine once a week when you connect the batt - then
you can figure there's a current drain.
to test electrically for a current drain, with the engine off, you
femove the battery main positive clamp................and put a test
light between the battery bable and the batt. terminal.
the light should not light up at all, even dimly.
be aware that any thing being on, intereior light, clock etc........will
make the test light be on during this test.
but if *everything* is off............including radio and everything
...............the light should not light up at all.
but say what your REAL, REAL symtoom is exactly, and I'll tell you howt
proceed in the most direct manner.
and if you don't have a Remote Stater Switch ..........a tool - a
starter button with wires and alligator clips on it............you MUST
have one. Period,
one can not trouble shoot starter issues effectively or quickly, or
effeciently, without this basic tool.
I keep mine in my daily driver van or car, it's that useful.
scott
www.turbovans.com
Don Hanson wrote:
> ...It may help some listee who's maybe wanting to learn to test the output
> of a van's alternator.
>
> I'm trying to figure why my SO's old chev farm truck won't keep starting.
> 70s era 350 Chev that's been un-killable. She uses it carelessly around the
> place to drag, haul horse sh*t, go to the dump, etc. It gets absolutely no
> care..Lately, she's been jumping it to make it run..today, I get the
> pleasant task of 'fixing it'..Love the Honey-do's...not..but..
>
> So, the battery is 7 years old..Probably time for a new one, yes? After
> cleaning all the ground points and the terminals and putting it on the
> charger overnight, it shows 12.57 at the terminals when the truck is running
> and the same when it is not running...
> "Aha!" I think, "The alternator is shot, too" So I dismantle enough so I
> can put my multimeter onto the alternator terminals, but I realize I know
> not what to expect or haven't a clue as to how to diagnose the readings I
> get. There are two smaller wires leading to a double spade plug in a rubber
> boot. I get a low voltage reading across those like about .4 or somesuch..
> There is one larger wire on a ring connector that is bolted on to a post on
> the alternator. That one disappears under the headers, perhaps going to the
> starter?..anyway, I read the same voltage, truck running, (12.57) off the
> large post (output?) as I get off the battery terminals when I read directly
> across the battery..I assume, and this is the question, that the large wire
> is the output for the alternator and should read +13~ v..right? My van, I
> get a reading across the battery of around 13.4 when the motor is on...12.7
> or so when it's not running.
> Did I do right? Should I get more than "ambient-- same as the battery"
> voltage from that larger terminal on the alternator? Should I pull the
> alternator and take it to my local autoparts, where they advertise "Free
> Electrical testing"? And get another battery at the same time? Help...I am
> an electrical dunce..
> Thanks and sorry the question isn't Van-centric on a Wednesday, yet.
>
> Don Hanson
>
>
>
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