Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing !***@#! wont start!!

Ken I doubt its the starter relay behind dash as the fact that dash lights are dimming suggests a considerable attempted current draw which can only come from starter area. The poweful piggy back solenoid which mechanically engages the starter pinion as well as making a high current contact to starter motor itself draws around 30 amps. The starter windings then take in the order of hundreds of amps.

I still therefore think, given your explanation of issue, a fault exists with main battery feeds or possibly the piggy back solenoid as originally suggested. By all means change the starter relay if it's easily accessible behind dash, in the unlikely case it is the culprit since otherwise it will prove it's not. If so then check again the local battery negative chassis connection and the extra flexible strap from chassis to engine block. Also the direct cable from battery positive to starter motor solenoid. If the latter you will need to buy new starter motor anyway as I doubt they are still available separately.

Thanks again for all the help - AA man was great - found that the starter motor ignition wire (exciter wire he called it) had high resistance so is corroded or damaged somewhere. Booked in to have that replaced next week.

Ken

Ken ... I hope he's right ... however if it's the wire from the ignition that activates the solenoid he's talking about I'd venture that, in spite of it's high resistance, it's doing it's job as the symptoms seem to indicate the sort of current draw that only an activated solenoid can provide.? ... always hard to know these things when the car isn't there in front of you to try stuff.

K

I share your view K - I did wonder if the ring gear pinion/solenoid has somehow seized - but when you can play with them things become more apparent and that's why I am reluctant to fault find long distance.

This happened on my Singer Chamois and a good smack on the starter motor freed the mechanical jamb until I could take it off the car.

Glad he found an issue Ken. The wire he is referring to is the one that runs from starter relay behind dash to the piggy back solenoid trigger. As the solenoid can take around 30 amps, if replacing the cable I would use chunky 10mm2 cable to minimise volt drop especially if OE one was underspec'd as they often are. Unusual fault but high resistance connection here may have the solenoid only attempting to move it's armature without achieving full movement to make contacts to starter motor itself.

Slightly suspicious in keeping with Image that enough current is being drawn to dim panel lights though. Given there are two functions to the solenoids operation, mechanical engagement of starter pinion then making of starter contacts, there are also two windings involved, a pull in coil and a holding coil both pulling against a strong return spring, so this may be relevant.

If a new starter/solenoid turns out to be required as well you won't be wasting the cost of replacement trigger cable especially if you upgrade it. Please let us know therefore the final fix on this issue.

At least if a new solenoid is necessary, it can be fitted without removing the starter, or at least it can on the Bv8. But even twenty years ago, some replacement solenoids were poor quality.

Around thirty years ago we used to sell Bosch replacement solenoids for same brand car size starter motors used on Guzzi V twins among others. They required their connections to be soldered into end cap from memory before bolting back together. Maybe for this reason I assumed they were no longer available as a standard alone item, for most brands at least.

Happy to be proved wrong though.

As best I can remember having stripped a Bosch solenoid on a pal`s 928, many years ago...as you typed Richard, the end cap on the solenoid had two soldered connections for the coil ends, which required to be unsoldered to remove the cap and expose the innards.... The copper disc which shorts the the battery terminal to the starter motor winding terminal was deeply pitted where it made contact with both terminals. It was just a case of cleaning up the contact points on both terminals and turning the disc to present that which was it`s reversed side to the terminals... Worked a treat.. I suspect by now solenoids will be constructed differently in that it may be impossible to strip and rebuild them...

My own thoughts are they are made similarly but being an integral part of a starter motor are only sold as a unit, it being no longer viable to offer a part that requires more than nut and bolt replacement.

I can remember the day when the local accessory shop even stocked bearings for the Lucas ACR alternator. I bought a Mini and the front bearing was rattling like a goodun, probably an over zealous jet wash. I stopped on the way home, and got the front bearing, "just like that"!