starter motor

[Bernie]

A question - probably for Vince...

I've just got to one of those "significant moments" - spinning the starter for the first time. The loom is partly installed, the battery is in position, the spark plugs are still in their boxes, so I just thought I'd make sure it would work.
Turned the key - nothing. It could just be that the thing is knackered - it hasn't been used for about six years, but it could also be that I haven't wired it up right. The solenoid has four connections - two fat ones, one for the battery/ignition switch and other for the motor itself, and two thin ones. I've connected up the one with "ign" next to it to the start position of the ignition key, and it gets power when it should - but what what's other one for? In the Rover diagram it seems to be connected to a complicated ballast resistor, but the Pilgrim diagram doesn't seem to have it at all.

help....

cheers

[Bernie]

Forgot to say - a Lucas starter on a Rover 3.5 V8

[SimonP]

The ballast resistor is connected in series with the positive side of the coil. It drops the coil voltage to about 6 volts under normal running conditions. (the "ballasted" coil is designed to run at 6V)

Inside the solenoid (big relay) on top of the starter motor are two sets of contacts. One connects battery positive to the motor windings, the other connects battery positive directly to the coil, bypassing the ballast resistor.

Your battery voltage drops with the huge load presented by the starter motor (down to about 7-8 volts on a bad day) So, even then, it assures that you get a healthy spark to start the engine.
Also, the ballasted system allows a better spark at high RPM than conventional systems because the current wil build up more quickly.
Electronic ignition systems generally use different methods to achieve the same results.

Secondly, if you are getting power to the start terminal, where are you picking up the negative on the meter? If you are measuring directly from the battery negative terminal, it could be as simple as a poor or missing engine earth strap. Check the voltage again using the engine block as negative connection.
Check the spade terminal you are using on the starter. Test resistance from each spade terminal to the engine block. The one which reads just a few ohms is the one which must connect to the "start" position on the key switch.
(Disconnect battery negative lead when doing these resistance tests, to avoid damage to your meter, should you accidentally contact battery positive!)

Does this help you?

Simon

[Bernie]

Thanks Simon

So,if I can just re-iterate in different words, the second small terminal is just an output to the coil, shorting the ballast resistor (which I won't have, because I'm going electronic) - so I just need to make sure I've connected the start voltage to the right terminal, which I may have got wrong.
I just put the engine earth strap on the other day, and tested it, but I'll do that again too.

cheers

[SimonP]

That's exactly it!

Simon

[Bernie]

Thanks Vince. That may well be it - no click, so it could well be seized after all this time. I'll give it a try.

[VinceGledhill]

If you short the battery positive to the motor connection with a bit of heavy cable you will here the starter turning over. It won't turn the engine at this stage because it will be disengaged from the flywheel.

Just one more point. I would recommend a trip (with starter in hand) to Lucas or one of their agents. You will probably find that a replacement won't be more than about £25.00. Might be worth it to know you have a factory re-conditioned unit on your car that won't let you down.

If you do go direct to Lucas then make sure you get a discount (at least 30%) They get 45 from the factory, 30 is standard trade discount.

Regards
Vince
Time served Auto Electrician
Lucas Leeds 1979-1983

[russell_ram]

If you're going to replace the starter motor I would not go for a direct SD1 replacement. I would go for one from a 4.6L Range Rover, about half the size/weight of an SD1 unit but twice as powerful (and it's Bosch bit not a Prince of Darkness component :9 ). Bit pricey though, £135 without an exchange unit (from Rimmers).

Russ

[Bernie]

Thank you gents

I crawled under this afternoon and took the starter out - and I'm pretty sure the solenoid is open circuit. I have another that I've just retrieved from a spare P6 engine (free to anyone who wants!), and it gives a very low reading from the small terminal to earth, as opposed to none on the other one, so I have high hopes!

[VinceGledhill]

If you have got a main battery positive and you have good connections to the starter then you can simply test the starter by shorting a wire from the solenoid terminal to this battery positive.

Take a look at the enclosed (badly drawn diagram) Simply connect a cable between the two points "x" and the engine should turn over. If not then check your voltages as you do so. If the solenoid dosn't click in then it may have sezed in the bore. They are easy to strip down and put back together.

HTH

Regards
Vince
Time served Auto Electrician
Lucas Leeds 1979-1983