Faulty solenoid?

[johnc]

I've just tried to turn over my Rapier after a major resto,electrical mods include change to neg earth,new alternator and battery but the solenoid only 'chatters' and the starter shows no signs of life. Am I right in thinking the solenoid is faulty and if so how can I test it?
Cheers
John

[suffolkpete]

It sounds like a discharged battery, a poor connection to the battery or a poor engine earth. Did you remember to re-connect the engine earth strap? The solenoid chatters because when it connects the starter, the voltage drops to such a level, due to the load, that the solenoid releases, the voltage then rises again and the cycle repeats. I assume your Rapier has a solenoid separate from the starter. If it has a a manual button, press this and see if it makes any difference, or you can try (carefully!) shorting together the two large terminals on the solenoid. If neither of these makes any difference then the problem is that there is simply insufficient current available to operate the starter and you need to check the battery, all the connections to the solenoid and starter and the earth return.

[johnc]

Thanks for the reply.
I've checked all connections to (new) battery, engine earth and checked solenoid with mulitmeter (pressing button shows completed circuit).What seems odd is that when I try on the key the solenoid 'chatters' but when I try it on the button it 'hisses'
I'm wondering if I've mis-connected some wires which were on the control box,now replaced by a fuse box in conjunction with alternator (ACR).The ones connected to the solenoid (battery side) are to the ignition switch and light switch,on shared spade terminal previuosly to A1 on the control box.
I've also by passed the ammeter as I beleive this won't cope with current from alteranator,by connecting the two brown cables together.
Any further comments would be appreciated as I'm tearing my hair out,well what little I've got left

[TerryG]

If you short across the solonoid does the engine turn over?
I assume your one has 3 wires, battery positive, starter and ignition. it can't really be wired up wrongly so if shorting across it starts the car then it is almost certainly faulty.
(just because a battery is new doesn't mean it is good, i have had two DOA over the last 5 years or so)

[johnc]

Just tried shorting across solenoid terminals,a few sparks and just 'hisses'not even a peep from starter.Battery is fully charged.Also tried another good battery same result.

[TerryG]

Have you checked that the starter has a good earth? it's possible there is corrosion between the body and the engine block that is stopping it getting a good circuit.

[Young Farmer]

Might be stating the obvious but will the engine turn by hand, or is the starter stuck? Sometimes the old inertia starters can lock into the ring gear.

[JPB]

Might be stating the obvious but will the engine turn by hand, or is the starter stuck? Sometimes the old inertia starters can lock into the ring gear.

And don't forget to turn the engine backwards to do this (I.E. rock the car backwards with the gearbox in top) or it may jam it up even more solidly.

[johnc]

The plot thickens
I've removed the starter (Lucas M35G) and tested it using jump leads ,at first it spun into life without a problem but after a couple of tries it fails to turn.
I've removed the end plate etc and find that the shaft has about 3mm end float,the bushes are worn but have quite a bit of length left,the springs are OK but the commutator copper is worn to a concave shape and there is no undercut between the copper strips.It seems to me that this is the root cause of my problems and a replacement starter is needed,does the the panel agree

[suffolkpete]

If a replacement is easily obtainable and cheap then that's probably the best way to go. If there's enough copper left on the commutator though, it could probably be reclaimed by turning down the commutator on a lathe until it's cylindrical again and undercutting it with a broken off hacksaw blade. Motors sometimes cease to work because the commutator segments have become shorted togther by copper and carbon debris and cleaning out the undercut will bring them back to life, though yours sounds well worn.