My '85 Series III has been through an uncharacteristic period of reliability lately, but last weekend that changed.

On trying to start, the engine cranked over very slowly as if the battery were flat. However, the battery was new less than a month previously so I wondered if it was a dud battery with a bad cell or suchlike. I went back to the battery shop and he tested it with load tester, smart tester and traditional acid hydrometer test. All passed. So we tried a different new battery on the car and that would not crank either. It therefore looked like a cabling problem or something wrong with the starter motor.

I returned home and removed the starter motor (not an easy job on these cars due to very restricted access). Testing it on the bench, it appeared to be okay as the pinion clicked into place and span as you would expect. I therefore checked all the cabling: battery positive to terminal post 1, terminal post 1 to terminal post 2, terminal post 2 to starter, engine to body ground and body to battery negative. All were good but I decided to replace the terminal post to starter cable as it was a bit smaller than the others and the terminals were not in optimum condition. On refitting the starter motor there was no improvement. Monitoring the battery voltage when cranking showed it dropped to about 9.5V whan trying to crank.

So the motor came off again and I removed the solenoid from the motor. Then metered out the resistance between the two main terminals with the solenoid engaged. It was high resistance, around 1k ohms so this appeared to be the problem. Solenoid introducing high resistance into the circuit. As I am in Thailand, spares are not available locally for these cars. About 99.9% of the vehicles on the road here are from Japanese car companies (mostly made locally here). So I decided to open up the solenoid.

To get the end cap of the solenoid off, it is necessary to unsolder two terminals which are the ends of the coil winding (circled in blue on the picture below). On doing so, I found the contacts inside were very dirty:




I gave the contacts a good clean up and reassembled the solenoid. After that, when closed, the resistance across the terminals to the starter feed was negligible, as it should be. So I fitted the solenoid back onto the starter and replaced the starter onto the engine. However, the problem still persisted! Same as before, sluggish crank and big voltage drop at the battery.

So the starter came off again (at least I was getting better at the fiddly job of removing and replacing the starter by this stage).

I opened it up to look inside, and discovered that one of the brushes had a broken wire:



This morning I went to the local auto-electric specialist in town to see if he had any brushes to suit, but unfortunately he did not. So I decided to have a go at soldering a wire to the remaining tail of copper wire coming from the disconnected brush. I then gave everything a good clean up and reassembled it all. A quick bench test was good so I fitted the starter to the car again.

Now she cranks over normally again and starts as she should.

I will order in a set of brushes from UK to do a permanent repair later, but meanwhile I am pleased to have the car driveable again.

So the learning points from this experience:

• Bench testing a starter on no load is inconclusive - it needs to be under load to simulate real life conditions
• It is possible to service the solenoid
• The brushes in the starter are not difficult to replace, so it is worth trying this rather than fit a whole new starter. The suppliers I normally use have new starters listed at a price in the region of £200, and for me that would probably double by the time I added air freight and import duty / VAT on arrival in this country. Brush sets can be purchased for as little as £8

 

Terrific dianosis, testing and repair Andy, congratulations and thanks for posting it.