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John McCormack

STARTER MOTOR SPINS BUT DOESN'T ENGAGE

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Occasionally, maybe 1 in 5 times, when turning the key my starter motor will spin making a horrid noise and not engage the flywheel.

Sometimes it works next try, sometimes it takes a few tries. It has always started but one day it won't.

I have been travelling for 2 1/2 months with the car unused so I expect when I get home it will play up.

Removing the starter from a RHD PI is a job of work so I want to know the solution, if possible, before I do.

Solenoid, starter or ???

 

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There is always the possibility of a knackered ring gear.

Stuart.

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My car does this maybe 1 in 20 starts. The more I use it the better it seems to be. Very interested to see what others have to say.

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I had that: ring gear was worn in one section. Sometimes engagng a gear would turn the engine just enough to allow it to engage. Otherwise always park on a slope so you can trun the engine slightly without  asking the passenger to give a push !

Peter

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You don't mention if your starter motor is standard or high torque. I experienced a similar problem on a high torque starter motor. Clearly the motor gear wasn't engaging the flywheel, yet examination of the flywheel with starter motor removed did not show any alarming damage. Examination of the motor also did not reveal any issue and testing it with battery power showed correct function with the solenoid operating and gearwheel moving along the shaft.

Eventually I bit the bullet and bought another new hi-torque starter motor, fitted it and it has performed perfectly ever since. I can only assume now that although the motor gear wheel on the original motor moved enough to engage the flywheel when tested off the car, then the force behind that movement was insufficient to engage it when fitted, suggesting perhaps that the solenoid was losing performance.

Check to see if the gearwheel is damaging the ring gear directly by not meshing, or if there is witness on the ring gear front face that suggests gearwheel on motor is not actually meshing.

Hope it helps.

TonyC

 

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Thank you all. It is possibly the original starter I believe.

Like Brucer, it does it less often when the car is regularly used.

If it was the ring gear I would have expected it not to engage at all if the damaged bit of the ring gear was lined up with the starter. That is what happens with a TR2.

An electrician said it was a clutch in the starter motor, something to do with the solenoid. He thought it was common to the TR5/6.

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8 minutes ago, John McCormack said:

 

If it was the ring gear I would have expected it not to engage at all if the damaged bit of the ring gear was lined up with the starter. That is what happens with a TR2.

 

It will reach that point, then you have to turn the engine slightly by a push when in gear. Each time it grinds a bit more of the ring gear wears....

It will get worse. Mine was a daily driver and got worse.

Peter

Edited by Peter Cobbold

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My car has done this since I bought it 10 years ago, the gearbox has been out twice in that time and the ring gear is as it should be, hardly any wear, so maybe it is a quirk of the starter motor.

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Hopefully it's not a ring gear. Ring gear teeth tend to wear at three points, the engine previously stopping prior to a start when a piston has  hit TDC.

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1 hour ago, John McCormack said:

Thank you all. It is possibly the original starter I believe.

Like Brucer, it does it less often when the car is regularly used.

If it was the ring gear I would have expected it not to engage at all if the damaged bit of the ring gear was lined up with the starter. That is what happens with a TR2.

An electrician said it was a clutch in the starter motor, something to do with the solenoid. He thought it was common to the TR5/6.

I would go to to a different electrician.   There is no 'clutch' in a starter and no solenoid in the OE one either.

The OE has a Bendix drive, that uses inertia and a scroll to push the pinion onto the starter ring as the starter starts to turn.    This scroll, and the Bendix itself, can get dirty with clutch dust etc.  preventing it working properly.    If you can get the starter off, clean the Bendix with brake cleaner, and lubricate it with GRAPHITE powder, never grease, because that will attract more dirt.

Also worth checking that the starter cables are in good condition, and the external solenoid switch, so that the maximum current cant hrow the Pinion a the Flywheel well!

JOhn

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4 hours ago, john.r.davies said:

I would go to to a different electrician.   There is no 'clutch' in a starter and no solenoid in the OE one either.

The OE has a Bendix drive, that uses inertia and a scroll to push the pinion onto the starter ring as the starter starts to turn.   

JOhn

John, the TR5-6 has a pre-engaged starter complete with solenoid.

The problem could be a weak/dirty solenoid causing a reduction in pull-in to engage with the flywheel. This could explain why it is less troublesome when used regularly.

Cheers

Graeme

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I agree, I'd look at the main  solenoid and its yoke. Have a look at the starter section of the original Lucas fault guide courtesy of Vitessesteve:

https://app.box.com/s/1grrnsn3ez49a2rlej9h4d5zj87bh1s3

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On ‎9‎/‎27‎/‎2018 at 11:02 PM, foster461 said:

Neil ?!  Welcome back.

Thanks Stan

Hope all is well at your end 

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On ‎9‎/‎27‎/‎2018 at 11:02 PM, foster461 said:

Neil ?!  Welcome back.

Good to see you back Neil:):)

 

Cheers

 

Mike

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5 hours ago, ntc said:

Thanks Stan

Hope all is well at your end 

Wishing you and your family all the best Neil. TR3 and TR6 both running well for the most part but my own starter issues brought me to this thread originally. Hopefully the cause was the corroded +ve battery cable and that may also explain why my overdrive (j type) was randomly dis-enaging.

 

Stan

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Hello guys, about ring gear, could someone please explain why the teeths are chamfreined on the opposite side of the starter pinion ?

My clue would be that it's a old stock who has been used (from a car with an inertia starter motor ?), but as most (all ?) of my 6 pots have their ring gear fitted this way…..

Another point : who could supply good quality ring gears ?

Again, I don't want to waste time and money on poor quality parts….

 

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On 9/28/2018 at 7:12 AM, john.r.davies said:

I would go to to a different electrician.   There is no 'clutch' in a starter and no solenoid in the OE one either.

The OE has a Bendix drive, that uses inertia and a scroll to push the pinion onto the starter ring as the starter starts to turn.    This scroll, and the Bendix itself, can get dirty with clutch dust etc.  preventing it working properly.    If you can get the starter off, clean the Bendix with brake cleaner, and lubricate it with GRAPHITE powder, never grease, because that will attract more dirt.

Also worth checking that the starter cables are in good condition, and the external solenoid switch, so that the maximum current cant hrow the Pinion a the Flywheel well!

JOhn

I had the car at our Triumph workshop last week for a different reason. He went to start the car and the starter motor span and didn't engage. His first words were "starter clutch slipping". Now I haven't yet pulled a TR6 starter apart but he is the 2nd person who knows TR6s inside out who has said the same thing.

I have a spare one, I will dismantle and see what is inside.

Edited by John McCormack

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I have this issue with my starter too.

My engine has just been rebuilt with a new ring gear, so worn ring gear is unlikely to be the cause. It was happening before the rebuild and I found that the old ring gear was worn in the usual places so I assumed that was the problem. I'm now convinced its something to do with the starter itself. The teeth on the bendix looked OK to me when I cleaned and tested the starter during rebuild but I'm not an expert in any sense. If anyone can spot the likely cause of the problem, I'd appreciate it.

20180628_114118.jpg

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Sean

When you tested the starter , what exactly was the outcome. Was it completely dead  i.e no clicking of the solenoid or some noise

but no obvious turning. A full description will assist in the correct diagnosis /  possible solutions.

Bob

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35 minutes ago, bob-menhennett said:

Sean

When you tested the starter , what exactly was the outcome. Was it completely dead  i.e no clicking of the solenoid or some noise

but no obvious turning. A full description will assist in the correct diagnosis /  possible solutions.

Bob

Hi Bob,

It had sat on the shelf as removed from the car for over 4 years while the rebuild was going on, and on initial test it turned really slowly. Having taken it apart and cleaned / lubricated the relevant parts as per the picture above, it worked perfectly in a bench test and had a very good voltage drop etc. On the car it works well and starts the car perfectly, except that every so often instead of engaging and starting the engine it whirrs with a sort of high grinding noise and doesn't turn the engine over. Does this a couple of times when the key is turned, then reverts to working perfectly again.

Cheers,

Sean

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