Starter Motor

[NevSpit]

Good evening all. 
So first off all, for once, this does not involve my Triumph but my ‘85 Mini.  I hope you forgive me for asking on the forum given the non Triumph nature but I know you are all knowledgable people and I am presuming it is I generic issue…

Every so often I go to start the car and nothing happens i.e the engine does not even turn over. The starter motor is trying to work as I noticed on one occasion the lights dimmed so it must be drawing some current. My initial thought was the earth lead and that has been cleaned up and then subsequently replaced.
However, if I put the car in gear and rock it slightly then try again it fires up beautifully. I have done this every time I have the problem recently and it keeps working. But why?  If I know that then  hopefully I can fix it. 

Many thanks for any ideas,

Paul

[johny]

I think you have a pre engaged starter and its gear is failing to mesh with the flywheel. This can be due to damage of the gears and by moving the engine slightly the gears can then engage correctly. I would remove the starter and inspect both its gear and the teeth on the flywheel - you should be able to see all these through the hole by rotating the engine....

[Stratton Jimmer]

If you have an inertia starter, the dog may be sticking in the starter ring. The idea with these is that the motor is not initially engaged with the starter ring and when current is supplied, the dog leaps forward and engages. If it is already engaged, you will get the symptoms you describe - heavy current draw but no action. Rocking the car backwards while in gear will usually free the dog which can then do its job properly. The shaft must be clean so that the dog can run freely too and from the starter ring. As Johny says, you can find out what the problem is by removing the motor and examining the starter ring and motor.

[cliff.b]

1 hour ago, Stratton Jimmer said:

If you have an inertia starter, the dog may be sticking in the starter ring. The idea with these is that the motor is not initially engaged with the starter ring and when current is supplied, the dog leaps forward and engages. If it is already engaged, you will get the symptoms you describe - heavy current draw but no action. Rocking the car backwards while in gear will usually free the dog which can then do its job properly. The shaft must be clean so that the dog can run freely too and from the starter ring. As Johny says, you can find out what the problem is by removing the motor and examining the starter ring and motor.

I have had this problem multiple times over the years with a variety of cars.

Usually, hitting the starter with a hammer released the Bendix, until the next time.

[Gary Flinn]

Not sure what type of starter a 1985 Mini would be fitted with, probably the Pre-engaged type with the solenoid on the Starter Motor?

If its failing to engage a check and clean of the drive gear with WD40 or similar may help but I don't think access is that good with a Pre-engaged starter motor from memory

If it is the earlier Inertia type with a separate Solenoid then, a clean with WD40 and checking the Bendix mechanism works and springs back smoothly usually sorts them out.

Disconnect the battery to be on the safe side if you are removing the Starter Motor

Gary    

[NevSpit]

Thanks all that has given me food for thought. Whenever I have had starter motor issues before there has always been a noise of some discription accompanying it whereas this does not so was baffled. A quick Google does indeed suggest a pre- engaged starter (not something I was familiar with) so I will attempt to remove it at the weekend and inspect the gears and free movement. Thanks again. 

[Pete Lewis]

if pre engaged ( has a solenoid pigy back on the motor ) it may just be corrosion of the main contacts  

the motor should not power up till it is engaged 

, no noise sounds like its not getting the power switched in 

on many  pre engage the solenoid   index's  the pinion 1/2 tooth each time its triggered so it should always engage ok 

Pete

[johny]

But its strange that jiggling the engine a bit then gets it to work🤔

[Unkel Kunkel]

I think ‘85 seems to be the year there was a change from inertia to pre-engaged.

As others have indicated that’ s the first  thing to establish.

An inertia starter’s Bendix gear can get stuck up with bell housing debris - clutch dust and a bit of oil seems very effective in doing this.

A pre-engaged one might, as Pete says, have poor solenoid contacts- they can be a bit thin on some makes.

-Let us know what you find 

[Pete Lewis]

can you  take a picture ,  would make this easy ???

Pete

 

[Colin Lindsay]

This is the Mini starter from 1985, after they changed over:

 

[Piglet]

I've had a Mini that had that same issue. Called a sticky starter (not kidding) and there is a cheap way of fixing it with a kit that I'm sure used to be on eBay but I knocked up my own with some wire and a few cheap electrical bits. It solved it for a while but it does happen again every now and then. Eventually I bit the bullet and bought a hi-torque starter. Bear in mind this Mini was a 1380 with 108bhp!

One way of easily checking. Tap the starter with a sturdy bit of metal while you crank it over. If it starts...it's a sticky starter.

Alex

[johny]

Well give us a bit more info Alex, whats the problem and how does the wire and cheap electrical bits fix it?

[Piglet]

It's a solenoid and some wiring and a fuse. All I can remember sorry but if you Google 'sticky starter' there are videos of how to do it.

Alex

[NevSpit]

Update…

Taken the starter motor out and it is an inertia type. I get the impression that this particular car was right on the cusp of changeover…

The gear is not smooth as you can see from the photo where it will hold position by itself. Will try and free that up now…

The edge of the gear looks like it has seen better days as well!

[johny]

Try to feel all the way round the teeth of the flywheel on the inside face. An engine quite often stops in the same place so a particular point on the flywheel gearing gets hammered repeatedly😟

[Pete Lewis]

bendix do  get a hard life  but a good wash with petrol will get it free and ready to roll again

i wouldnt worry too much about the tooth damage , but a a ash  never oil it   fit it clean and dry and the pinion will whiz up and down freely 

and returning  fully      thats just crudded up with clutch dust 

it will work ok

Pete

[NevSpit]

So… I have given it a good clean, admittedly with some lubricant but after reading Pete’s post I cleaned that off with brake cleaner as that was to hand. Seems dry and clean and still goes up and down better than it was. 
I did feel the fly wheel and it seemed ok although it was too hot for me to feel all the way round, at least it is on a different section for now. I also smoothed off some of the ‘burrs’ of the gear and it is all back in and working. Will just have to wait and see if that improves matters or not.

As always thanks for all your advice and guidance on the forum. 

[johny]

Looking good although a stuck bendix wouldnt explain why it didnt spin when you energised it. Unfortunately theres a slight possibility that it has an electrical fault where one part of the rotor winding has failed (usually this is where the starter motor always stops so it has a hard life on start up) and then it wont start from that position. This might explain why after jiggling the rotor it then works....

[Pete Lewis]

lets face it you can go and change the pinion and then find a winding has failed and the motor runs like a flat battery 

but if it fires over briskly and works as expected you have the utopia or compromise   situation of what you want and what you expect.

its   good a clean is working for now  so  plod on and get the smiles back and put the wallet away  ...always a good feeling 

Pete

[NonMember]

2 hours ago, johny said:

a stuck bendix wouldnt explain why it didnt spin

Instinctively, no, it shouldn't. But it does seem to have that effect. I slightly wonder whether the motor relies on its own inertia to get the flywheel started, and if the Bendix dogs too soon then it hasn't yet built up enough momentum.

[johny]

S'possible but if stuck engaged I thought starter motor bearings soon fail.... We'll have to see, fingers crossed👍

[Pete Lewis]

with the gear ratio if stuck in mesh and you rev the engine it would soon wreck or explode the motor due to vastly excessive rpm.

field winding do fail and this reduces the power output , almost sounds like a flat battery  starts slow and builds a bit  the low power can engage the bendix but stall the motor 

its then locked in till you rock the car or give it a whack 

pinion return relies on the engine starting and the speed increase of the flywheel flings the pinion back up its bendix drive 

Pete

[Unkel Kunkel]

If it is very high mileage  have a good look at it generally - as well as  the Bendix gear - if the bearings have play and the brushes are well down or stuck in their holders, commutator looks worn/ burnt with  black segments and it has that acrid  “burnt  electrics”smell, then get a complete replacement   motor rather than replacing all the individual worn out parts. 

They aren't that expensive weighed  against how long they are supposed to last and the fact that starters  do have a tendency to give trouble on cold wet windy nights when you need to be somewhere else very quickly.

[daverclasper]

4 hours ago, Unkel Kunkel said:

They aren't that expensive weighed  against how long they are supposed to last and the fact that starters  do have a tendency to give trouble on cold wet windy nights when you need to be somewhere else very quickly.

I think I have heard that "new ones" aren't always great?. Maybe more expensive to have it rebuilt by someone reputable, though worth it in the long run?