Lotus Elan

Is my starter motor dead?

PostPost by: lotusbzz » Mon Aug 05, 2019 3:39 pm

Is my starter motor dead?
This is what is going on:

I'm nearly ready to drive on the road my S4 after years of restoration.
Engine has been fully rebuilt and runs well, but yesterday after many test of the engine that is assembled on the chassis and body, suddenly I see some typical sign of low in battery.
Battery is nearly brand new but maybe a bit weak due to check up of the electric wiring so charged the battery overnight; checked the voltage the day after , 13 volt ok.
Try again but the starter motor doesn?t' crank the engine, it's very slow and for sure not strong enough to fire the engine .
Headlights off, clutch pedal down , low friction as much as possible, but slow and every time at I try again, it's slower a bit.
The cord from the starter solenoid to the starter motor is a bit warm, but I can touch it, no problem.
The starter solenoid trip when you turn the ignition key , you can listen the "tock" noise, but no way to make the starter motor cranking the engine.
Earths are all connected and checked with voltmeter the continuity, they ring all.
At the input of the starter solenoid 12.58 Volt but it's 9.38 when under crank.
Maybe it's the pinion that it's engaged? ? I took the sparks away and tried to crank the starter motor, it's faster then before ( there is no compression) maybe enough to disengage the pinion.
Refit the sparks: same story and it's worst because now the starter motor is stuck!
Last chance: connect directly the starter motor with a spare battery, if the solenoid is fault, at least should should run free:
ready, set, go ... no way, stuck!

What I do?
1. Do I buy a new starter motor?
2. regular Lucas?
3. the High torque Wasp ( do I have to reroute the wire from the usual location of the solenoid to the bottom where is the starter?)

please some comfort is appreciated, I believed to make My Elan running to go in holiday next week, mmmhhhh probably next year
saluti a tutti
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PostPost by: prezoom » Mon Aug 05, 2019 4:00 pm

First check the battery to chassis ground/earth and make sure it is clean and tight. Then check the engine to chassis connections and make sure all connections are tight. Same for the connections to the solenoid. If the starter fails after doing all the above, it may be time for a new starter.

Should you choose to convert to a high torque pre engaged starter, as has been stated before, simply run a connection from the spade terminal on the new starter to the battery connection. Your original solenoid will then provide battery to the new starter and in turn to the solenoid connection, which will engage the solenoid to push the gear into the flywheel and then provide current to the starter motor. No need to rewire anything in the existing wiring system.
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PostPost by: MarkDa » Mon Aug 05, 2019 6:44 pm

+1 to checking earth - don't forget that the main earth in the boot is through a threaded bobbin so it's not just a matter of tightening in the boot.
Make sure you tighten the bolt from underneath as well to get continuity to the chassis.
My experience was that my body settled down over time after reinstallation and I got a good couple of twists on the bolt before it pulled up tight again and then voila - lots of current again.
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PostPost by: webbslinger » Mon Aug 05, 2019 11:08 pm

I just checked my voltage with the starter engaged and the drop was about what you mention. Still, I'd try jumping your battery with another one to make sure it isn't that before buying a new starter.
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PostPost by: mbell » Tue Aug 06, 2019 3:32 pm

Try jumping with battery connected to the solenoid input and Earth on the engine. Rules out most of the wiring and limits fault to starter, solenoid or wiring between them.
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PostPost by: Quart Meg Miles » Tue Aug 06, 2019 10:54 pm

The standard Lucas motor should be good on a standard S4 and used to be OK on the Sprint engine. I reckon 9.38 V on the motor should be enough but perhaps the solenoid is high resistance.

If the pinion is jammed it will never un-jam just by applying voltage; you need to push the car while it is in 4th gear (and ignition OFF). So free the pinion and then use your battery directly on the starter motor and if it doesn't spin the engine properly then the motor is faulty. If it does spin the engine suspect the solenoid.

Good luck

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PostPost by: lotusbzz » Wed Aug 07, 2019 6:52 am

Thank you all for the support!
Some update:
The solenoid is not the problem, the problem occurs even with a spare solenoid
The battery is fully charged , there is a bright green led on the display of the battery charger
The pinion is engaged or can be engaged by the spinning of the starter because I can clearly listen the engine cranking
It seems that the starter motor is not powerful, but last week it was, I used it several time with engine that started with single first crank
When reassembled the engine I didn?t serviced the starter motor, it was running at that time, that seems to be expired sigghhh :oops:

Today I try with the battery of may Volvo, then maybe I?ll go for a new starter motor ... the same of course because

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PostPost by: 2cams70 » Wed Aug 07, 2019 9:26 am

One of the many beauties of the Lucas starter motor is that you can easily loosen the single screw that clamps the cover band at the end and remove it for inspection of the general health of the starter. Once the cover band is removed you can readily see the condition of the commutator and brushes and look for any discoloration of the windings that might indicate overheating.
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PostPost by: types26/36 » Wed Aug 07, 2019 9:55 am

lotusbzz wrote:The battery is fully charged , there is a bright green led on the display of the battery charger Paolo

I would not trust that as a true indicator the battery condition, it may read the battery voltage at 12.6 + but it does not show the battery under load.......I would have it "load tested" by the battery people.
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PostPost by: lotusbzz » Wed Aug 07, 2019 2:24 pm

More info about the starter motor fault, hopefully help the Posterity because from my side I've already order the new starter.

Anyway this happed today:

I don't know how but the pinion disengaged and made the engine running for a moment!
I'm sure that it disengaged because releasing the ignition key the engine stops to rev few second after!
wawww great result .... but after that tried again and it stuck again!

The moral of the story: when you restore your Elan you must service your starter motor otherwise you do not go in holiday with her!

Have a wonderful summer wherever you are!
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