Date: Tue, 13 Sep 2016 23:17:58 +0000
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: Engine Ground voltage drop under load, please help diagnose.
In-Reply-To: <136578C8-EEAE-480C-998E-211DF39B3F6C@gmail.com>
Content-Type: text/plain; charset="windows-1256"
Yes. Consider #4 wire as you have a 90 amp alternator.
Dennis,
From my phone.
________________________________
From: Dennis Jowell<mailto:dennisjowell@gmail.com>
Sent: ý9/ý13/ý2016 6:32 PM
To: Dennis Haynes<mailto:d23haynes57@HOTMAIL.COM>
Cc: vanagon@GERRY.VANAGON.COM<mailto:vanagon@GERRY.VANAGON.COM>
Subject: Re: Engine Ground voltage drop under load, please help diagnose.
Dennis
Would the grounding you are suggesting also be advised for an 88 WBX 2.2 engine?
Dennis Jowell
Scotch Hollow Farm
Newbury, Vermont
> On Sep 13, 2016, at 6:19 PM, Dennis Haynes <d23haynes57@HOTMAIL.COM> wrote:
>
> I would start by looking at the ground strap itself. Also, you may be getting miss lead so you also need to look at the B+ wire from the alternator to the battery. It is common for the this wire to see a significant voltage drop to being somewhat undersized and after all these years the conductors are going bad.
>
> Losing voltage with the system under load is normal. .5 volt just across the ground strap is high for just headlights and running load. Try replacing that ground with a 2 gauge wire. Also consider another ground at the alternator. I would suggest a 6 gauge for that one.
>
> Dennis
>
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Christophe Guilbert
> Sent: Monday, September 12, 2016 1:08 AM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Engine Ground voltage drop under load, please help diagnose.
>
> I have a vanagon 1983 air-cool CA.
>
> I would really appreciate some help to diagnose my problem , even my mechanic does not understand it.
>
> Here is the story:
>
> My battery is new and read 12.6v . I have a new alternator which deliver 14V
>
> When the van idle I read 13.71V at the battery terminal. When I start lights and fan blower , I read 13.24V.
>
> I tried to check if I had any leak between the battery terminal and the alternator under load (lights and fan blower):
>
> For terminal + , I have none , well something like -0.1V
>
> For terminal - , not only I have -0.5V at the alternator level but also to any ground point of the engine, which is way too much ! ( I have -0.1V only if I am not under load)
>
> In order to remind how the engine is grounded , here is the pathway , from battery to the body using a ground strap , than from body to transmission front mounting using a ground strap, than from transmission front mounting to the transmission via metal contact and/or
> 3 bolts and stud. than from transmission to the whole engine.
>
> Trying to understand where my 0.5v drops come from , I checked if I had any voltage drop between the battery ground terminal and the ground strap terminal bolted to the transmission front mounting . I have none
> (-0.04v) . So voltage drop must happened between the transmission front mounting and the transmission or the engine. I plugged my voltmeter between the ground strap terminal going to the transmission front mounting and the engine (any points) and I found -0.45V.
>
> When I plugged my voltmeter between the ground strap terminal going to the transmission front mounting bolt and one of the transmission bolt (after making it bare metal), I got -0.35V. So the main culprit seems to be the connection between the transmission front mounting and the transmission itself. I removed the transmission front mounting , clean bolts ,studs, washers, any point of contacts, I make them bare metal, used deoxit D5 and di-electric grease before putting every back. I retest the ground voltage between the battery and the engine and I got -0.4V (instead of -0.5V) under load.
>
> From this point I don't know what to do and would appreciate any explanation and advices.
>
> I am thinking to reground the engine . If I quickly used a jump start cable to reground the engine , I reduce my voltage drop from -0.4V to -0.2V. I guess I can do better with a proper dedicated ground cable .
>
> I would rather avoid that option thought because I would like to fully understand what's going on first.
>
> Any though.
>
> Thanks for any help.
>
> Chris
| 
