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tony_ack

Intermittent start issues

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Hi everyone, just want to try to narrow down whether this is the ignition switch or starter...

Occasionally I'll turn the key to start and it won't turn over. Sometimes it kicks in after a few seconds, sometimes nothing (and sometimes starts first time)

  • Fuel pump primes at ignition on
  • cross-over relief relay engages when turned to crank
  • bump starts okay

My thinking is the starter because of the relief relay engaging when 'cranking', but just wanted to check as changing either is not the easiest job!

 

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Does sound like starter motor to me. Perhaps try checking you have voltage at the starter motor whilst someone turns the key to be sure.

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Check all your starter motor connections, especially the to the solenoid if you cant hear that one click when engaging the ignition key, that particular connection is very prone to corrosion.

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1 hour ago, Bauhaus said:

Check all your starter motor connections, especially the to the solenoid if you cant hear that one click when engaging the ignition key, that particular connection is very prone to corrosion.

Definitely do that. What we don't discuss very often is that the quality of copper wiring used by VW in the late 80s through to the mid 90s was, frankly, poor. A lot of my engine bay faults are caused by the wiring oxidising behind the insulation; the copper wasn't pure enough before being rolled into wiring; humidity was poorly controlled when the wiring was sheathed. Both VAG and Mercedes used to use the same manufacturer for their looms and both suffered a terrible reputation for faults arising from cable harness failures. Check resistance levels from battery to solenoid, solenoid to starter. Check all the contacts carefully.

There's something else - the ignition relay (IIRC it has the number 53 on it) is capable of doing exactly what you describe. It will cut a starter in the middle of turnover; and it can kill an engine suddenly. Always helpful to have a spare one of those. I'd replace it anyway and see if that helps.

Edited by Bruno

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Thanks for the replies, I'm fairly sure now it's the wire to the solenoid - thr connector is quite loose, and when I take it off, the symptoms are exactly the same. I've cleaned it up and tried to secure it a little better and it's been okay since, fingers crossed.

Sent from my Pixel 4 using Tapatalk

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