Testing the starter motor


Date: Fri, 12 Jun 1998 08:06:22 -0700
From: Richy_T
To: mini-list@autox.team.net
Subject: Re: Dodgy Starter Motor (maybe)
Sounds like it very well could be the starter motor. The brushes sometimes go on these. Here's a few tests

  1. disconnect the big 12V wire and measure the resistance between the terminal and ground (or use a bulb and wire from the +ve terminal of the battery [Note: Make sure you have the bulb in-line or it's wire melting time]


    (the yellow thing is a bulb!)

    The resistance should be very low (or the bulb should light up).

  2. See if there's a small end-cap on the starter motor. If there is, remove it and you might see the square end of a shaft. Use a spanner to turn it a bit then try the starter again (make sure you take the spanner off first). If it starts, this could indicate worn brushes or oxidation of the commutator. (It's also a handy fix until you can get it fixed properly).

  3. Hit the starter motor with a hammer (no, really). The brushes are spring loaded and may be caught. This is also another get-you-home fix. (Usual disclaimers apply)
If it is the brushes, replacement is fairly cheap. On my Escort (old mkII thing), it was a case of snipping the braided wires off of a metal bar and soldering a new pair on. A warning that this requires more heat than a standard soldering iron provides (and it's a wonder I didnt blow the house up with the device I rigged up from the gas to do it). Whilst you're at it, a bit of fine wet and dry around the commutator to clean up any oxidation due to sparking is a good idea too.

Rich


Stolen from the Mini list, 1998