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STARTER MOTOR SPINS BUT DOESN'T ENGAGE


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Sounds like the solenoid is not consistently pulling the pinion in. Check out the linkage and solenoid coil for a loose wire and maybe resistance. The electrical checks are covered in pages 12-14 of this manual (thanks to Vitessesteve):

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

Edited by Mike C
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11 hours ago, SeanF said:

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

Mine is the same. The more I use the car the less it does it.

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Sean   I side with Mike that the solenoid is possibly suspect. A comment , did you clean up the commutator end face

lightly with sand paper. From the picture the brushes themselves seem to have enough "meat" left on them. They are not catching when in their normal position are they ? Not impeded by the wires / debris. ( Sometimes the cause of a graunching sound when the brushes are on the way out or the brush holders are clogged up with carbon dust ).

Good clean sound earth strap , engine to bodywork. Connection clean / good , feed from ignition to starter. Firm attachment at the terminal that can't be waggled by finger pressure. Clean surfaces where the Starter is bolted to the engine ?

Bob 

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Sean,

my started motor refused to start now and then, so not exactly your issue, but it was the nut on the motor terminal (the second nut if you know what I mean) that was oxidized and not fully tightened. Make sure the nut, rings and terminals are al clean and tight.

Waldi

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My TR6 has made the same horrible noise on 1 in 10 to 20 starts since I bought it in 1980. I was advised to change the starter ring when I overhauled the engine sometime in the early '80s - made no difference, still did it and still does it to this day. The starter is original and has never been apart: 130, 000 miles and 47 years, not bad Mr Lucas but why does it do it?

It is an embarrassing noise as it really only does it when there are people standing around the car admiring it before you set off. There is a law governing that coincidence.

Mick

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4 hours ago, Mick Forey said:

It is an embarrassing noise as it really only does it when there are people standing around the car admiring it before you set off. There is a law governing that coincidence.

Mick

Very true Mick. In a nice way, I'm glad it doesn't just happen to me. Sods Law :D

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12 hours ago, Mick Forey said:

My TR6 has made the same horrible noise on 1 in 10 to 20 starts since I bought it in 1980. I was advised to change the starter ring when I overhauled the engine sometime in the early '80s - made no difference, still did it and still does it to this day. The starter is original and has never been apart: 130, 000 miles and 47 years, not bad Mr Lucas but why does it do it?

It is an embarrassing noise as it really only does it when there are people standing around the car admiring it before you set off. There is a law governing that coincidence.

Mick

Yep, always when people are watching the car.

I dismantled the spare starter and there is a clutch in it, to allow the pinion to disengage when the engine fires. The clutch is described in Mike C's attachment above.

Whether the clutch also operates when starting I can't make out.

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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

Hi John. There is a clutch in the starter. It allows the pinion to disengage when the engine fires. It may also operate when starting, I can't make it out. See Mike C's attachment below.

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Does the random graunching noise happen even when using a hi torque motor?

i had a reoccurrence of the original starter failing to work today but it did work after a 5 minute rest. I also have the random graunching mick talked about.  I’m hoping that a change to hitorque starter motor might solve both issues.  Anyone had any experiences to share?

 

cheers

 

dave

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I used to have the graunching and failure to start regularly on my 1974 CR up till about 5 years ago when I had the Lucas starter fully overhauled by auto electricians here in Adelaide since when its performed faultlessly. Unfortunately I don’t have a detailed list of what was repaired or replaced so not much help!

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Well I bit the bullet and bought a wosp.  It was emotional doing midwifery duties removing the Lucas starter..... but what a difference on turning the key!  Hopefully no more graunching nor problems starting. Fingers crossed.

 

cheers

 

dave

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  • 2 years later...

Coming back to this thread my starter still plays up occasionally, spinning making a noise but not engaging. It hasn't got any worse or better over the 3 years since I first started this thread however I don't like it.

I have dismantled my spare starter motor and it looks ok except the roller clutch drive (integral to the pinion drive) spins freely in both directions. It is meant to be a one way clutch as per section 86.60.00 of the Owners Manual, locking when starting and then spinning in the other direction when the engine starts.

I am assuming the roller clutch in the starter in the car is also on its way out.

It seems to be a straightforward job to change it, if I can get a new one at the right price.

Does anyone know if the clutch/pinion gear is available anywhere? I checked Moss and TRF and no longer available. Rimmers say it has been superseded but they don't say by what.

My alternative is to install a new hi torque starter.

If I go this route which model hi torque have owners used they would recommend.

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13 hours ago, RobH said:

Are any of these any good John ?  

https://www.autoelectricalspares.co.uk/pinions--drives-177-c.asp

WOSP seems to be the favourite for a geared high torque starter, going by comments in previous threads. 

 

Hi Rob. Yes, I am just checking with them whether this one, 131723 Starter Motor Drive replaces Lucas TNB133 54240984 , M418G, is suitable for the M418G starter in the early TR6s. The part number on my drive is different but it might be OK.

$70 delivered seems reasonable.

Very valuable help, thank you

Having now disassembled the pinion/clutch drive I am not sure how the clutch works. I had the starter tested some time ago and the motor spun but the pinion slipped under load.

Now with the starter apart the pinion will lock one way but not he other, moving it by hand which isn't much load obviously. What I assume is the clutch, the bit with the long part number on it, spins freely in both directions.IMG_0868.thumb.jpg.915a95274514512e7ebdabaf52738880.jpg

Any advice welcome.

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  • 1 year later...

I know that this is an old thread, but my 6 started to have the same problem. At first it was so occasional as to not even register that there was a problem, but got progressively worse. The car was fitted with a high torque starter, but still had to be push started outside of Hay on Wye castle, very embarrassing!

I have tried the following so far with no luck:

New WOSP starter.

New battery leads with all of the earth points cleaned up.

New battery.

It is now at the stage of spinning and shrieking at every turn of the key so I can’t even get the car out of the garage.

Anyone got any more ideas?

Thanks.

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When you had the starter off, did you look at the condition of the teeth on the flywheel ring gear?   

Engines can have particular positions that they often stop in, so the ring-gear gets heavier wear at those points. 

Edited by RobH
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17 minutes ago, Twizzle said:

I know that this is an old thread, but my 6 started to have the same problem. At first it was so occasional as to not even register that there was a problem, but got progressively worse. The car was fitted with a high torque starter, but still had to be push started outside of Hay on Wye castle, very embarrassing!

I have tried the following so far with no luck:

New WOSP starter.

New battery leads with all of the earth points cleaned up.

New battery.

It is now at the stage of spinning and shrieking at every turn of the key so I can’t even get the car out of the garage.

Anyone got any more ideas?

Thanks.

Badly worn ring gear on the flywheel.

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41 minutes ago, Twizzle said:

I checked the whole ring gear by turning the engine when the motor was off, it all looked good to me?

the front of the teeth wear, not the entire tooth. The symptom I had was the progressive worsening over months of daily use. Often putting the car in gear and pushing it an inch or so would find a good spot on the gear.

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This ring grinding is a problem across the entire 6 cylinder family of engines, some time ago a cure was suggested in the Triumph 2000/2500/2.5Pi magazine, however it does need the gearbox to be removed first so you can see what's going on, then with the pinion engaged, turn the flywheel over slowly, and continually check that the pinion can move in and out of mesh with the ring gear and see if there are any tight spots, if so slightly enlarge the starter motor fixing holes in the engine backplate (corresponding enlargement of the gearbox holes required) so that the starter motor can move away slightly from the ring gear, ..... have to say this method worked on my old 2.5 Pi saloon.

Cheers Rob  

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1 hour ago, ntc said:

Being a six pot the flywheel will lose teeth at three points and the starter will always rest in one of those spots and will just spin 

Am I dreaming this…?

the ring gear of a 6 pot can be pushed off the flywheel and thus away from the starter,  by the action of the starter bendix gear teeth not aligning every time with the flywheel teeth.   
 

Please advise  if this is wrong.
 

  On the 4 pot engine later flywheel the ring gear is bolted to the flywheel to stop this action.

 

Alternatively the crank thrust washers are about to drop out and the crank and flywheel are all moving away from the starter.

Edited by BlueTR3A-5EKT
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