Help requested- Solenoid?

[IanM92]

I disconnect the battery when no plans to use the car for a week or so. Yesterday on touching the live lead to the battery terminal there was a loud "clack" from the starter motor which sounded like the motor trying to engage onto the flywheel teeth. Decided to continue with connecting up the battery, again one or two "clacks" then silence. Key into the ignition and the engine started fine but the starter motor after disengaging tried to re-engage. I am sure you can imagine the noise!
My guess is the solenoid needs a refurbishment but could it be something else?

[yroll]

I disconnect the battery when no plans to use the car for a week or so. Yesterday on touching the live lead to the battery terminal there was a loud "clack" from the starter motor which sounded like the motor trying to engage onto the flywheel teeth. Decided to continue with connecting up the battery, again one or two "clacks" then silence. Key into the ignition and the engine started fine but the starter motor after disengaging tried to re-engage. I am sure you can imagine the noise!
My guess is the solenoid needs a refurbishment but could it be something else?

The solenoid can't be activated because its in poor condition. either you have something that shorted it or you have another problem.

Check connections at starter.

[smithersoli]

Sounds like you have something shorting from the starter terminal to the main battery live lead as they are next to each other on the starter motor.

If you take off your airfilter then they should be easily visible, you could try electrical tape if the insulation has been melted as a temporary solution.

I would suggest being very careful however as any fuel leaks from your carbs will drip into this area and sparks could end up with an engine fire, I was very lucky i managed to put one out before the bodywork was damaged on mine.

(That was faulty fuel pipe though)

Oli

[alanbell]

the solenoid has a direct positive electrical supply from the battery. when the ignition switch earths the solenoid it engages the drive pinion with the flywheel and then energises the starter motor. the only way,

[alanbell]

the solenoid has a direct positive electrical supply from the battery. when the ignition switch earths the solenoid it engages the drive pinion with the flywheel and then energises the starter motor. the only way, so far as I know, for the drive pinion and fly wheel to engage is for the solenoid to be earthed. a faulty solenoid can spin the starter motor with out engagement (whines) or can engage without spinning the starter (clicks) just as with an almost flat battery. but since your car starts and then the starter motor engages with the engine running I would think that the solenoid is being earthed. all you have to do is find the earth. if it is not from the wires connected to the solenoid I do not know if a solenoid can develop a fault which will allow it to find earth through the starter motor which is earthed. good luck.
ps again my knowledge fails but perhaps the solenoid could earth through a faulty starter or ignition relay.
pps I cannot delete the above, it is there because I some how created two copies of the same post, sorry

[IanM92]

Thanks very much for your suggestions.
Initially I replaced the starter relay which achieved nothing. This was followed by the complete removal of the airbox and clean up of all connections on the starter, solenoid and earths which were all in good order and without any signs of melting or sparking, all to no effect.
Discussed the problem with the owner of an independent company specialising only in Lotus cars, particularly Esprits and Excels and have booked it in for 17th April which will be cancelled if I have one of those eureka moments. They have carried out the more challenging work on the car over the last ten years, mostly but not all for the previous owner.
Decided against replacing things willy nilly as there is no guarantee of success.
As you will have guessed by now my electrical knowledge is "somewhat limited".
Looking forward to meeting up at the Croft weekend.

[yroll]

the solenoid has a direct positive electrical supply from the battery. when the ignition switch earths the solenoid it engages the drive pinion with the flywheel and then energises the starter motor. the only way, so far as I know, for the drive pinion and fly wheel to engage is for the solenoid to be earthed. a faulty solenoid can spin the starter motor with out engagement (whines) or can engage without spinning the starter (clicks) just as with an almost flat battery. but since your car starts and then the starter motor engages with the engine running I would think that the solenoid is being earthed. all you have to do is find the earth. if it is not from the wires connected to the solenoid I do not know if a solenoid can develop a fault which will allow it to find earth through the starter motor which is earthed. good luck.
ps again my knowledge fails but perhaps the solenoid could earth through a faulty starter or ignition relay.
pps I cannot delete the above, it is there because I some how created two copies of the same post, sorry

I can't agree with you on this, the solenoid has constant earth not positive.
At least on my Excel and every other vehicle i've worked on.
Otherwise you are correct, i would guess it's a loose connection behind steering wheel or at starter.

[alanbell]

yroll'
I quote from the excel service notes " THE POSITIVE CABLE IS ROUTED THROUGH THE CHASSIS BACKBONE TO AN INSULATED POST BOLTED TO THE CHASSIS BEHIND THE RIGHT HAND ENGINE MOUNTING. A FURTHER SEPERATE CABLE CONNECTS THIS POST TO THE STARTER SOLENOID AND A FURTHER CABLE CONNECTS THE SOLENOID TERMINAL TO A SECOND BINDING POST AHEAD OF THE RIGHT HAND DOOR HINGE POST, TO PROVIDE A TAKE OFF POINT FOR MOST OF THE POSITIVE FEEDS." this means that the solenoid has a permanent positive feed. the wiring diagram does not show the solenoid as having a dedicated earth. there are three terminals on the solenoid, one connects to battery positive, to supplies and to the alternator, one to the start relay and one to the starter.
I would be delighted if you would explain how this is a permanent earth, as there are not any switches or relays between the battery positive and solenoid.

[yroll]

yroll'
I quote from the excel service notes " THE POSITIVE CABLE IS ROUTED THROUGH THE CHASSIS BACKBONE TO AN INSULATED POST BOLTED TO THE CHASSIS BEHIND THE RIGHT HAND ENGINE MOUNTING. A FURTHER SEPERATE CABLE CONNECTS THIS POST TO THE STARTER SOLENOID AND A FURTHER CABLE CONNECTS THE SOLENOID TERMINAL TO A SECOND BINDING POST AHEAD OF THE RIGHT HAND DOOR HINGE POST, TO PROVIDE A TAKE OFF POINT FOR MOST OF THE POSITIVE FEEDS." this means that the solenoid has a permanent positive feed. the wiring diagram does not show the solenoid as having a dedicated earth. there are three terminals on the solenoid, one connects to battery positive, to supplies and to the alternator, one to the start relay and one to the starter.
I would be delighted if you would explain how this is a permanent earth, as there are not any switches or relays between the battery positive and solenoid.

All i know is that you need to get positive feed on the solenoid for the starter to run, this is working with or without ignition.
This must conclude permanent earth?
I have tried this on my car, might be other solutions on other cars but i''vh never seen any.

Regards

Joakim

[amarshall]

The solenoid has a permanent heavy duty live and earth. Neither of these is switched externally.

There is a third terminal, which is driven by the start drop-out relay. This is what triggers the solenoid when the ignition key is turned. When the relay switches across to the start position (cutting all other circuits on the car), it energise a "relay equivalent" inside the solenoid which closes the contacts on the heavy duty circuit - this energises the coil which moves the pinion and also allows current to the starter motor.

Technically, although there is a permanent positive feed to the outside of the solenoid, there is no part of it which is permanently energised.

Translation - you're both almost right and both almost wrong

The solenoid can be tested by creating a short between the permanent feed terminal and the start terminal, but I can't recommend doing this in-situ because of high currents, poor access and the risk of the engine turning over.

[yroll]

The solenoid has a permanent heavy duty live and earth. Neither of these is switched externally.

There is a third terminal, which is driven by the start drop-out relay. This is what triggers the solenoid when the ignition key is turned. When the relay switches across to the start position (cutting all other circuits on the car), it energise a "relay equivalent" inside the solenoid which closes the contacts on the heavy duty circuit - this energises the coil which moves the pinion and also allows current to the starter motor.

Technically, although there is a permanent positive feed to the outside of the solenoid, there is no part of it which is permanently energised.

Translation - you're both almost right and both almost wrong

The solenoid can be tested by creating a short between the permanent feed terminal and the start terminal, but I can't recommend doing this in-situ because of high currents, poor access and the risk of the engine turning over.

Am i correct if i say that the permanent-positive is the one at the starter not at the solnoid, or ist it one at the starter and one at solenoid?
Starting to realize What he was meaning...

[amarshall]

Am i correct if i say that the permanent-positive is the one at the starter not at the solnoid, or ist it one at the starter and one at solenoid?
Starting to realize What he was meaning...

The permanent feed goes to the solenoid and then there is a bridge across to the starter from the other terminal on the solenoid (that makes 3). Current on this bridge is switched inside the solenoid. So, the starter does not have a permanent live.

(Section MH, Sheet 02 for later cars).

[yroll]

Am i correct if i say that the permanent-positive is the one at the starter not at the solnoid, or ist it one at the starter and one at solenoid?
Starting to realize What he was meaning...

The permanent feed goes to the solenoid and then there is a bridge across to the starter from the other terminal on the solenoid (that makes 3). Current on this bridge is switched inside the solenoid. So, the starter does not have a permanent live.

(Section MH, Sheet 02 for later cars).

OK, then i must have it wrong in my head Or another starter, not...

[alanbell]

I have looked closely at the wiring diagram and the car and I cannot see a heavy duty earth attached to the solenoid it must earth via starter motor when the internal contacts close. I know the function of each part but as a layman I regard the internal workings of such a relatively small item as the solenoid as miraculous.

[IanM92]

I am smiling again, an hours "magic on the electrics" by the experts and all is well. So what was wrong and what needed replacing? Nothing was found to be specifically wrong although the alarm system received close attention, and nothing was replaced. The starter/solenoid performs as it should so it must be assumed the short, if that is what it was, became sorted along the way.
All that is required now is a clean and polish and she will be ready for the 9 days of Hillclimbing events, Yorkshire Dales, Lake District and, Croft.
I am now convinced, as if I needed convincing, that a little knowledge is a dangerous thing.
Thanks again for your suggestions and for the interesting discussion on the starter/solenoid electrics.