Solenoid

[jackb_ms]

I've spend my saturday dismantling my 21 to get access to the starter motor.

I have discovered, the solenoid is not (anymore) strong enough to pull the gear inside the starter motor.

It is the first time this has happen.

 

Did someone had the same kind of failure of a solenoid?

 

Jack

 

 

 

Emily, The Very Yellow 21

[charlie_pank]

Have you tried pressing the big red button (or turning the key) whilst tapping the solenoid with a hammer? - if that works, it probably just needs dismantling and cleaing with some wet+dry.

 

Have you checked all of the connections to the solenoid. Solenoids don't get weaker, so it's likely you've got some high resistance somewhere in the circuit...

 

Have you had a look at Mark's instructions on how to rebuild the solenoid - here?

 

 

[jackb_ms]

Here is the list of what i have tried and what i've found disconcerting.

Remove starter moter from engine.

Remove solenoid from starter motor.

Check the solenoid with out spring, work fine the bolt is pull . I've powered the solenoid directly from the battery, battery voltage 12.69Vdc

Check solenoid with starter motor and doesn't work.

 

Where is the problem? Any ideas?

realease spring to strong?

 

Jack

 

 

 

Emily, The Very Yellow 21

[Chris W]

Jack

 

Check solenoid with starter motor and doesn't work

What exactly do you mean by this? Do you mean you cannot hear the solenoid pulling in when it is bolted back on to the starter motor?

 

The solenoid will not get mechanically weaker. There may or may nor be something wrong electrically,

 

but check first.....the solenoid needs a small amount of lubrication on the plunger. Check that it hasn't got old dried up lubrication on the plunger.

 

Chris

 

2003 1.8K SV 140hp see it here

[jackb_ms]

Chris

 

I mean exatly this " I cannot hear the solenoid pulling in when it is bolted back on to the starter motor".

 

It worked for a track day and a trip down to Devon, 3 month in total.

 

It's a big mistery

 

Jack

 

 

 

 

Emily, The Very Yellow 21

[Chris W]

Jack

 

It may be an electrical fault. The solenoid has 2 coils on it, a "pull-in" coil and a "hold-in" coil.

 

When the solenoid initially operates the 2 coils act together in parallel to close the contacts that operate the starter motor. However, once closed, due to the physics, it takes far less current and hence coil power to hold the contacts closed. So the "pull-in" contacts are bypassed once the solenoid contacts are closed and the power that was used in this coil is now available as a bit of extra power to turn the starter motor. The hold-in coil has sufficient power to hold the contacts closed on its own.

 

2 possible causes of your fault come to mind.....

 

1. It may be that the pull-in coil has failed by going open-circuit. The hold-in coil, on its own, will be able to operate its plunger as there is little mechanical resistance when the starter motor is not connected. But it won't have enough power to close the contacts once bolted to the starter motor because it also has to pull a lever which moves the starter gear out into contact with the flywheel to facilitate starting. This is where the "pull-in" coil is necessary.

 

2. The mechanics of the starter motor lever which pulls the gear mentioned above into line with the flywheel is jammed for some reason.

 

I would have thought that with either fault though, you would hear something, even if it's only the hold-in coil straining to pull the contacts together.

 

Measure the current in both cases, viz: with and without starter motor connected. How much current is being drawn when connected to the starter motor?

 

Chris

 

2003 1.8K SV 140hp see it here

[jackb_ms]

Chris

 

Thank's for the info, I didn't know the solenoid had two coils.

 

The ohm value I can read between the "control" terminal and mass is 1.8 ohms.

Checking the current absorbed will be a bit more difficult to check.

I'll try to do it today or tomorow. Do you have a value for the current?

 

I'm going to dismantle this one and order an spare just for the incase.

 

Thanks again

 

Jack

 

Emily, The Very Yellow 21