Starter motor problems

[Cooper99]

The starter motor on my 2200 TC -74 only worked occasionally. Sometimes it started and sometimes it didn't. I have therefore replaced the starter motor with a new unused (NOS) of the same model in hope that this would fix the problem. It didn't.

When I turn the key, there is voltage to the terminal with white/brown cable (see picture below), so the starter relay works. But then nothing more happens. No response from solenoid or starter motor.

Anyone?

 

[sdibbers]

I would examine earth straps, the battery terminal and the positive cable from the boot to start.

These can still conduct lower currents, but overheat and add resistance at higher draws such as the starter. I had a similar problem a few years back with my starter being very slow to turn over. I just happened to notice a wisp of smoke from the positive battery terminal clamp when trying to start with the bonnet open (series one cars had the battery in the front). Sure enough, the cable had serious corrosion inside where it entered the clamp housing.

 

[colnerov]

If you apply voltage to the Brown/White wire, does the solenoid throw in? If yes then it's dirty contacts inside the solenoid on the heavy side or a fault in the motor. If not, then it's the solenoid or the mechanism is seized. Can you move the starter dog forwards?

 

[Cooper99]

I would examine earth straps, the battery terminal and the positive cable from the boot to start.

These can still conduct lower currents, but overheat and add resistance at higher draws such as the starter. I had a similar problem a few years back with my starter being very slow to turn over. I just happened to notice a wisp of smoke from the positive battery terminal clamp when trying to start with the bonnet open (series one cars had the battery in the front). Sure enough, the cable had serious corrosion inside where it entered the clamp housing.

The times the old starter motor worked it ran at normal/fast speed, so I think the terminals and wiring are in good condition. I have examined the earth straps. The battery is new.

If you apply voltage to the Brown/White wire, does the solenoid throw in? If yes then it's dirty contacts inside the solenoid on the heavy side or a fault in the motor. If not, then it's the solenoid or the mechanism is seized. Can you move the starter dog forwards?

Actually, the picture above show my old starter motor. The new one I just installed on the car.
When I apply voltage to the brown/white wire I can measure voltage at the terminal, but nothing happens. The new starter is "new" from supplier, but is an old NOS Unipart, so I suppose it is 30-40 years old. So, it's a bit strange that it should be faulty?!

 

[LS-1]

... The new starter is "new" from supplier, but is an old NOS Unipart, so I suppose it is 30-40 years old. So, isn't it a bit strange that it should be faulty?

NOS parts that have been sitting on a shelf for a number of years do need a good clean before you use them. I found this out recently after buying a NOS speedo. I fitted it to the P6 and found that it wasn't working. So upon taking it apart and freeing up and lubricating the moving parts it now works a treat.

Starter motors that have been dormant for years and years respond very well to a good clean and lubrication of certain internals. I did this very thing on a starter motor on a Triumph 2.5 PI I once had. It had been stored in a shed for 20-years before I bought it. Just check that the brushes and bairings have plenty of meat on them, and clean the solenoid. I applied a small amount of vaseline to the solenoid - I seem to remember reading about doing that from somewhere online.