Clicking Bosch pre engaged starter motor

PostPost by: Vaughan » Sun Sep 29, 2019 2:29 am

Any suggestions to fix a sticking starter motor solenoid? I've a Bosch pre engaged starter fitted and its just started to click before starting on the second or third turn of key, cars not been used much for last year...

Battery is fine, earths and wiring to starter all tight and in place, only thing I've not checked is the ignition switch but it does not feel loose.

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V
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PostPost by: rgh0 » Sun Sep 29, 2019 3:45 am

If the starter is clicking but not turning over it suggests that the contacts in the starter solenoid that send the main current to the motor are possibly dirty. The other cause could be the pinion jamming on the flywheel teeth and not fully engaging.

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PostPost by: 2cams70 » Sun Sep 29, 2019 8:01 am

Run a jumper wire direct from the battery +ve to the start terminal on the solenoid. If the starter cranks normally during this test then it's high contact resistance in the ignition switch circuit rather than the starter solenoid that is the culprit. If you run a Bosch pre engaged starter the current through the ignition switch is higher than with the original Lucas starter. The current draw from the Bosch solenoid is higher because not only does it switch the high current circuit but it also has to be strong enough to push the pinion into engagement unlike the case of the solenoid with the Lucas starter. If you run a Bosch starter it's best to use a separately wired 20 or 30A automotive relay so the ignition switch is spared from switching a higher current than it was designed to. The ignition switch may survive the higher current in the short term but over time the contacts will develop a high resistance.
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PostPost by: Vaughan » Sun Sep 29, 2019 9:27 am

Thanks for the suggested actions, I'l check tomorrow.

Cheers

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PostPost by: alan.barker » Sun Sep 29, 2019 9:49 am

+1 fit fused relay to supply pre engaged starter. Less current through ignition switch
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PostPost by: RichardS » Sun Sep 29, 2019 11:39 am

I have recently had a similar symptom.

On mine it was the the female spade connector from the ignition, which pushes onto the male connector on the starter motor housing. It had worked a little loose and a gentle squeeze of the female connector with some pliers tightened up the connection and solved the issue.

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