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MG MGB Technical - I have to hit my starter with a Stick?

All,

I have two rubber bumpered MGBs and the starters won't engage about half of the time until I open the hood and hit the starter a few times with a stick. Then they engage normally for a few tries and then I have to repeat the process. The starter relay is engaging in all cases. Ideas? Have I got bad brushes?
Thanks
Tom Gillett

You may have both bad brushes and stick solenoid. I would remove starter and check the brushes as they could be worn or sticking in their holders.c If they aare good then I would suspect the solenoid itself.
Check the solenoid output with a voltmeter while somebody tries to start the car.
Sandy
SANDY SANDERS

What Sandy said is correct but check that the brushes are clean and polish the commutator with glasspaper. There is also the possibility that there is a bad sector in the comm in which case the starter will need to be replaced.
Iain MacKintosh

The very first thing to ascertain is what noises it makes. The ignition switch operates a relay which makes a click, which operates the solenoid which makes a clunk, which energises the starter which grinds. So if you get the clunk it is the solenoid contacts, brushes or rotor. If you get the click but not the clunk it is either the relay contacts, solenoid winding, or connections thereto. If you don't even get the click it is the ignition switch or the relay winding, or again connections thereto. You can't be sure that hitting it with a stick is affecting the starter, or indeed anything at all, it could just be coincidence and the voltage/current needing a little while to burn through a bad contact.

Always best to do voltage tests in-situ first, removal is quite likely to disturb things such that it might not fail on the bench, but start doing so again shortly after reinstallation which would be frustrating.

Whilst some starters have an exposed link between the solenoid and the motor, which would allow you to check the solenoid contacts as Sandy advises, not all do.

A bad sector on the comm wouldn't normally be 'fixed' by hitting it with a stick unless you hit it hard enough to move the rotor onto a good segment!

PaulH Solihull

I have a similar problem with a ZA,and had the same 45 years ago with an A35!It whizzes round, but wont throw the Bendix unless you hit it!
Not sure if the B starter is a newfangled pre engaged type, but on the old M35 etc starters it was usually cured by taking the starter off & cleaning up the Bendix drive with paraffin & emery cloth or similar, then ensuring it is quite dry & NOT lubricated and problem usually solved. My starter comes off tomorrow for this treatment...hope this trick works.
DG Harrison

That's a different problem! The conventional wisdom is that you should never lubricate the Bendix gear (the spiral-cut shaft) or it attracts dirt and causes the pinion to stick. But having cleaned one several times and had it do just that sooner and sooner after each time an old hand told me to put just one drop of light oil on the spiral and after that I had no more problems with it.
PaulH Solihull

This thread was discussed between 22/11/2010 and 24/11/2010

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