Lotus Elan

Starter motor fault check list

PostPost by: ericbushby » Fri Jan 11, 2019 5:36 pm

Often there is a separate wire or small terminal for the internal solenoid. This, in the case of my Powerlite motor is connected directly to the main power terminal of the motor, but can be wired separately just in case you want to do something else.
Does this need connecting on your motor.
This should be covered in the instructions.
If the motor was jammed or stalled for some reason, you would see a dip in any lights that were on. try again with the headlights on to prove it.
Tell us more.
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Last edited by ericbushby on Fri Jan 11, 2019 7:28 pm, edited 1 time in total.
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PostPost by: Geoffers71 » Fri Jan 11, 2019 7:27 pm

Hi Eric, Thanks for your reply that has made me think. There weren't any instructions with the motor so I assumed the connections were.....
An obvious main power terminal, a protruding threaded stud with a nut.
There was also a spade terminal that takes a black wire fitted with a ring terminal. I assumed that this was an earth and used it as such, but maybe it wasn't :shock: Maybe, as I think your suggesting, it too connects to the main power terminal so that the solenoid is powered too as you say. Maybe the earth is the usual braided connection to the body of the motor via one of the fixing bolts! That would make sense.
Have I (with your help) hit on the problem??
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PostPost by: MarkDa » Fri Jan 11, 2019 7:37 pm

You probably don't need the old solenoid.
These 'high torque' (high rpm really) starters are usually pre engaged so the high current cable goes direct and the pre engagement mechanism uses the switch wire to engage the pinion which then makes the high current circuit and turns the motor.
I ecpect everything goes to earth through the casing rather than separately as you suspect
This may mean that that your initial problem was just the £15 solenoid?!
Or more favourably the pre engagement is not working (because you haven't connected it) so the motor doesnt turn.
A quick low current connection should soon sort it.
Whether you still need the old solenoid rather depends if you are running a ballast coil and want the enhanced spark while cranking.
Hopefully only a few minutes work to get the engine running again.
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PostPost by: Geoffers71 » Fri Jan 11, 2019 8:35 pm

MarkDa wrote:You probably don't need the old solenoid.

I'm keeping the old solenoid as I understand it acts as a relay as well as retaining a visual display of originality even though it isn't :D

I ecpect everything goes to earth through the casing rather than separately as you suspect

Yes, I'm happy that that's the case


This may mean that that your initial problem was just the £15 solenoid?!

No, don't think so, the Lucas motor was in very bad shape with broken brush wires

Or more favourably the pre engagement is not working (because you haven't connected it) so the motor doesnt turn.

Yes, having checked on line wiring diagrams I'm sure the black wire I thought might have been an earth should indeed be connected to the stud to which the main power supply is also .


Thanks Mark and Eric, you've both been very helpful
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PostPost by: mbell » Fri Jan 11, 2019 8:54 pm

Geoffers71 wrote:There was also a spade terminal that takes a black wire fitted with a ring terminal.


I think, as you're figured out, you just need this cable fitted between the main power feed and spade terminal on the starter.

The spade terminal supplies power to a solenoid that engages the pinion into the flywheel and internally to the starter connects the power supply to the starter motor. Resulting in the starter hopefully turning the engine over.

As suggest another option is to bypass the standard solenoid and run a permanent live to the starter and feed from ignition switch to the starter solenoid connection instead of standard fit solenoid. Personally I prefer the standard solenoid setup, I am not clean on having large unfused cable down in the engine bay and the standard solenoid is very accessible for checking if you have issues.
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PostPost by: collins_dan » Fri Jan 11, 2019 11:01 pm

The previous owner eliminated the solenoid on my S4 and connected the line from the ignition to the high torque starter. It worked fine for years, but recently stopped providing sufficient voltage to cause the pinion to engage. It seems like it wants at least 12 volts and was only getting 11. I searched and searched to figure out what was causing the voltage drop. Eventually, I decided to add a relay, based on suggestions from this group. I could have put a solenoid in, as it would have been more correct, but the relay was easy and cheap, and solved the problem. Dan
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PostPost by: prezoom » Sat Jan 12, 2019 3:53 am

When installing my pre-engaged starter, I left the original solenoid in place. Placed a short jumper wire from the main battery lead at the starter to the internal solenoid terminal on the starter. When the original solenoid connects B+ battery to the starter, B+ battery is immediately connected to the internal solenoid, which engages the pinion gear to the ring gear on the flywheel. Only I had one problem. I could hear the solenoid on the starter operating and engaging the pinion with the ring gear, but the starter motor was not turning. There was a small rubber vent tube exiting the solenoid housing that managed to work its way loose enough to slip between the discs that connect the B+ battery to the starter motor. Thus no current was getting to the motor. Took a while to figure out what was happening, because every time I took the starter out of the car and tested it on the bench it worked every time. Replaced the vent tube with a rubber plug that fits much tighter. So far, no more problems.
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PostPost by: ericbushby » Sat Jan 12, 2019 9:09 am

Geoffers,
The only earth connection you need is the braid across the engine mount to the chassis. Maybe that is the one you mean though.
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PostPost by: Geoffers71 » Sat Jan 12, 2019 10:57 am

Yes Eric I've done that and changed the other wiring as suggested and now everything works :D :D It is much noisier than I expected though, quite a clatter in fact. It's a pre-engaged pinion so I can't see why it clatters so. Hope I haven't done anything else wrong :roll: The motor is tight and secure against the bell housing so I can't see why it's so clattery. Maybe that's just the way they are.
Anyway much thanks again to all that helped.
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PostPost by: ericbushby » Sat Jan 12, 2019 11:09 am

Good, well done.
Difficult to comment on the noise, only to say that mine just sounds like a starter motor shoud. I suppose it is a bit late to ask if it has a 9 tooth pinion.
Have a listen to someone else's before you do anything.
Cheers, Eric
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PostPost by: Geoffers71 » Thu Jan 17, 2019 4:45 pm

Well I'm stuck as to what to do next. :? This hi-torque starter motor from SJ doesn't seem to be meshing properly although, of course, it's supposed to be pre- engaged. The noise from it when starting is alarming, a sort of graunching (is there such a word?) as if the pinion is not, as I said, meshing properly. It does start the car alright though. It LOOKS as if the body of the motor is flush and secure against the bell housing, but I can't be 100% sure as it's so difficult to see. I was initially worried that the pinion teeth, there ARE 9 of them, were not much more than a couple of cms long and might not be long enough to engage fully with the flywheel teeth, but it does have a label on it that says it's for a twin cam. I've loosened the securing bolts right off so that the motor is loose and wiggled it around to bed it in as well as I can considering I'm lying on my back and can't see anything. I tried to support it on a block of wood while tightening the bolts as I can't do both. Really fed up with it now, I think I'm going to find a local friendly garage who can have a look at it for me. Unless of course any of you bright souls have any suggestions :roll: :D :D
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PostPost by: Craven » Thu Jan 17, 2019 5:16 pm

IIRC there was talk that some pre-engage starters need a good 12v or more voltage on the spade terminal ( internal solenoid ) to fully pre-engage the pinion. It may be worthwhile checking the voltage on the spade terminal when cranking over. If low, you could rig a separate supply and try that.
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PostPost by: richardcox_lotus » Thu Jan 17, 2019 9:36 pm

It may be worth re-searching this site. I recall a previous thread (with pictures) of a pre-engaged starter where the pinion wasn’t long enough. It looked alright but only meshed to half the ring gear depth.

Regards
Richard
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PostPost by: 2cams70 » Thu Jan 17, 2019 10:39 pm

Geoffers71 wrote:Well I'm stuck as to what to do next. :? This hi-torque starter motor from SJ doesn't seem to be meshing properly although, of course, it's supposed to be pre- engaged. The noise from it when starting is alarming, a sort of graunching (is there such a word?) as if the pinion is not, as I said, meshing properly. It does start the car alright though. It LOOKS as if the body of the motor is flush and secure against the bell housing, but I can't be 100% sure as it's so difficult to see. I was initially worried that the pinion teeth, there ARE 9 of them, were not much more than a couple of cms long and might not be long enough to engage fully with the flywheel teeth, but it does have a label on it that says it's for a twin cam. I've loosened the securing bolts right off so that the motor is loose and wiggled it around to bed it in as well as I can considering I'm lying on my back and can't see anything. I tried to support it on a block of wood while tightening the bolts as I can't do both. Really fed up with it now, I think I'm going to find a local friendly garage who can have a look at it for me. Unless of course any of you bright souls have any suggestions :roll: :D :D


Graunch and clatter = Warning! - ring gear about to get chewed up. Is the pinion stroke of these starter motors such that the pinion is spinning before it engages? Whilst this is normal operation for the original Lucas distributor it's not how a pre-engaged starter should operate. Although the pinion may be 9T how does the pitch between teeth and the diameter compare with the original? There's lot's of stuff which good potentially go wrong in the design of a starter replacement.
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PostPost by: Geoffers71 » Thu Jan 17, 2019 11:36 pm

richardcox_lotus wrote:It may be worth re-searching this site. I recall a previous thread (with pictures) of a pre-engaged starter where the pinion wasn’t long enough. It looked alright but only meshed to half the ring gear depth.

Regards
Richard


Thanks Richard. I've found the previous discussions on similar issues and there seems to be a consensus that in some pre-engaged motors the pinion is too short and does not mesh sufficiently deeply into the ring gear. If this was the case here it would explain the graunching. I'll be giving Steve at SJ a call tomorrow to "discuss". Very tempted to go back to the old style Lucas inertia type. Thanks all for your inputs.
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