Lucas Starter Solenoid

Hi there folks,
I have the dreaded click when I try to start the engine, I give the solenoid a slight knock with the hammer and the starter motor works....

Question,
Is this a Solenoid fault or mabey its brushes, I strip the starter and find that two of the brushes are shorter than the other two brushes, I have them on order, but, what about the solenoid I cant seem to get the plastic end cap to come off, is there a way of checking to see if the solenoid is working, I heard that if you clip on jump cables to the solenoid you can find out if its operating.
But I dont know which connections I need to clip onto. All I have been able to do so far with the solenoid is spray some wd40 on it. plz help..

banzia

This happened on my Td5 and it was the brushes in the solenoid.
I had to take the starter off, a well documented pain in the arse, then the solenoid has an end cap which is removed and the brushes are inside. Another fiddly but easily do-able, just remember the sequence of washers etc when replacing the brushes.