[urq] intermittent start issue

[Steve Buchholz]

I think it is simple enough to describe in text form.  What you are doing is reducing the load on the ignition circuit by having the starter switch actuate a relay coil.  To do this you disconnect the small diameter wire to the starter solenoid and connect it to the cool of a 12V relay, the other end of the relay coil goes to ground.  Now you wire a contact on the relay that is normally open to provide a lower resistance path from the battery to the solenoid.  You probably already have a connection from the alternator or starter to your headlight relays (hopefully fused!)  If the relay has NO & BC contacts, connect the common terminal to the starter solenoid where the wire that is now controlling the relay was connected.  The NO terminal of the relay goes to the 12V source.  With this modification, the starter switch will now have a lighter load, and the increased resistance will not cause as large a voltage drop.

OBTW, be very careful when you perform Peter's suggestion ... disconnect the battery to prevent big time arcing and sparking should you touch +12 and the car body with your wrench ...

Steven Buchholz (mobile)

----- Reply message -----
From: "Keith Lloyd" <spotatashleys at hotmail.com>
Date: Mon, Sep 13, 2010 12:02 pm
Subject: [urq] intermittent start issue
To: "urq" <urq at pacbell.net>, <urq at audifans.com>, <audionly at gmail.com>

Pete/Steve Thanks for the replies. I'll try the positive lead clean up tip first and if no good then I'll perhaps get a new starter.
I have already converted my car to run the headlamps via relays  - but do you have a circuit diagram to illustrate how to wire a load reduction relay? I think it might be worth doing.
When I rebuilt my car I remade the heat shields and in fact increased their size a bit. I have a stainless one protecting the motor mount and an ally one protecting the starter and solenoid so I don't think it is a heat soak issue per se. However the worn brushes in the starter is probably a more likely cause.
Thanks again for the suggestions.
All the best
Keith

----- Original Message ----- From: "urq" <urq at pacbell.net>
To: <urq at audifans.com>
Sent: Sunday, September 12, 2010 10:49 PM
Subject: Re: [urq] intermittent start issue


> Over the years and several older Audis I've come to understand that there > is
> not a single issue, rather it is the combination of several factors that
> leads to hot start cranking issues.  Time and temperature cause the > voltage
> drop across the start switch and wiring to the solenoid to increase, > thereby
> reducing the voltage available to the starter.  I measured less than 9.5
> volts at a starter that was not pulling in.  The heat soaked starter > causes
> the magnetic field within the starter to work less efficiently.  Many > times
> the heat shield Audi originally installed on the starter disintegrates, or
> is not reinstalled when the starter is replaced.  This increases the > effect
> of the heat related issues.  Your experience with moving the car in gear > and
> getting a starter to pull in is a sign that the brushes in the starter are
> getting bad.
>
> VW had a TSB for our Audi's cousins which added a "load reduction" relay
> between the starter switch and solenoid if the voltage at the solenoid was
> less than 9.5 volts.  If you are considering adding headlamp relays to > make
> headlights brighter you may want to add a starter load reduction relay at
> the same time.  Doing so will likely make your cranking more reliable, but
> eventually other things will deteriorate and cause starter issues.
>
> I must say that IME, simple replacement of the starter restores the car to
> reliable starting.  The early US urqs had a stamped sheet metal heat > shield
> that covered both the solenoid and the motor itself, but the newer cars > seem
> to protect only the solenoid.  I found a nice insulation and foil sandwich
> heat shield for the 5000TQ that goes over the solenoid.  When I install a
> replacement solenoid I install one of these heat shields.  I did not find
> them in the garage to get the P/N, but they are in the FA.
>
> Steve Buchholz
>
> -----Original Message-----
>
> Chaps
> Bit of an issue with getting the old girl fired up.
> I used to use my WR every day but since last October I spent a lot of
> time,effort and cash having it resprayed and have decided to look after