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Help! Need someone to look at my starter motor!


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Right - the Meter Maid is back!

 

2. Sound - I was wrong about the moan. It does a t'clunk't and then a Brrrrrrr as it vigorously winds something round and then the same t'clunk't as you turn the key off again. You can listen to it here: http://www.whistlecroft.net/samples/starter.wav

 

Lisa

 

 

The solenoid engages (first click), the contacts make (something is going round), the engine isn't turning over

 

In my opinion, your starter is knackered*

 

If the wires to the solenoid were broken, it wouldn't click. If the contacts had failed, it would only click - ours does that sometimes

 

Take it off and get it looked at

 

Richard

 

*There is another possibility which is the ring gear. It's a bit unlikely though

Edited by RLWP
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The solenoid engages (first click), the contacts make (something is going round), the engine isn't turning over

 

In my opinion, your starter is knackered*

 

 

 

I wouldn't be so fast. That audio sounds exactly like the starter on Reginald's Gleniffer when the battery is a bit low. Spins up but the pinion fails to move forward and engage the ring gear.

 

Charge the battery a bit and it works fine. Otherwise use a bit of wood as a tool to hold the pinion stationary then it will climb the helix and engage anyway, and start the engine.

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I wouldn't be so fast. That audio sounds exactly like the starter on Reginald's Gleniffer when the battery is a bit low. Spins up but the pinion fails to move forward and engage the ring gear.

 

Yep - the Gleniffer has a bendix. The BMC uses a pre-engaged starter with a solenoid on the side. Different motor, different symptoms

 

To be clear, the BMC uses a solenoid to put the pinion in engagement with the ring gear. At the end of the solenoid stroke, it strikes the contacts to energise the motor. In the recording you can hear the click of the solenoid, then the motor running. There is no helix

 

The Gleniffer starter relies on running fast to use a spiral to throw the pinion into engagement. With low voltage, it doesn't run fast enough to throw the pinion out

 

Richard

 

Richard

Edited by RLWP
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To be clear, the BMC uses a solenoid to put the pinion in engagement with the ring gear. At the end of the solenoid stroke, it strikes the contacts to energise the motor. In the recording you can hear the click of the solenoid, then the motor running. There is no helix

 

 

Ah I see, thanks. That's where I was struggling, I didn't know which type of starter was on a BMC, never having owned such an exalted piece of engineering exotica. So far.

 

So yes given the BMC motor won't run until the solenoid moves the pinion forward, yet we hear the motor running with the pinion not engaged, it's pretty definitive the motor has to come off next for a look to see why. My money is on all the teeth missing from the bendix.

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My money is on all the teeth missing from the bendix.

Can I have your money then please since a/ it doesn't have a bendix and b/ bendixes don't have teeth!

 

Anyway, as Richard says it needs to come off and probably either the shaft has sheared /pinion come off the shaft, or the engagement fork is bust. I think if it was teeth missing from the PINION it would probably be making a graunching noise.

 

But of course, all that is a matter of opinion (a pinion, gerrit!)

Edited by nicknorman
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Thank you for all your thoughts. Just to add/reiterate:

It's NOT the battery - it does exactly the same with a fully charged portable battery in parallel. We didn't actually do yesterday's measurement with the powerpack in parallel (there is a limint to the number of things we can get in the engine compartment at once!) but we know that even with a fully-charged powerpack the symptoms are identical. We know that powerpack can start that boat when the main batter is flat and the the starter engaged so the powerpack isn't knackerd too!


Sounds like starter motor off is definitely the next step (oh bliss...) It's not easy to reach! At least now (thanks to you all) we've got the phone number of a man who is willing to come to the boat and the details of starter motor factors an easy drive distance away!

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Can I have your money then please since a/ it doesn't have a bendix and b/ bendixes don't have teeth!

 

Anyway, as Richard says it needs to come off and probably either the shaft has sheared /pinion come off the shaft, or the engagement fork is bust. I think if it was teeth missing from the PINION it would probably be making a graunching noise.

 

But of course, all that is a matter of opinion (a pinion, gerrit!)

 

 

YEs it does! 'Bendix' is a generic term

 

Can I have your money then please since a/ it doesn't have a bendix and b/ bendixes don't have teeth!

 

Anyway, as Richard says it needs to come off and probably either the shaft has sheared /pinion come off the shaft, or the engagement fork is bust. I think if it was teeth missing from the PINION it would probably be making a graunching noise.

 

But of course, all that is a matter of opinion (a pinion, gerrit!)

 

 

Yes very funny.

 

But getting back to your previous comment, I don't have any money, I've wasted it all on boats...

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Thank you for all your thoughts. Just to add/reiterate:

It's NOT the battery - it does exactly the same with a fully charged portable battery in parallel. We didn't actually do yesterday's measurement with the powerpack in parallel (there is a limint to the number of things we can get in the engine compartment at once!) but we know that even with a fully-charged powerpack the symptoms are identical. We know that powerpack can start that boat when the main batter is flat and the the starter engaged so the powerpack isn't knackerd too!

Just to reiterate what Richard says (since it being said twice helps to reinforce!) the starter works thus: when you turn the key, it powers a solenoid (electromagnet) which does two things. Firstly it pushes the starter motor's gear forward so that it meshes with the engine's starter gear ring. As it approaches the end of the travel (fraction of a second later) it makes a beefy electrical contact that puts power onto the starter motor.

 

As said, the motor is running so clearly the solenoid is doing its bit but the gear is not engaging or at least there is no drive. So as you say, nothing to do with battery voltage.

 

You will need to remove the starter motor and have it checked out. Possible causes are:

Motor shaft sheared or gear no longer connected to shaft*

Solenoid fork broken

Starter freewheel / sprag clutch (if fitted) broken (slipping)**

All teeth missing from starter pinion (unlikely unless there were previously some horrible noises)

One or two teeth missing from the engine's starter ring gear. Again, unlikely unless there had previously been sounds of distress.

 

*Some starters have a deliberately weak drive pin (connected the gear to the shaft) that shears if the engine kicks back. Aimed at petrol engines of course. So just possibly, it might only be a case of replacing the drive pin although to be honest I've no idea if such things are ever found on Diesel engines.

 

**most but not all pre-engage starters have a sprag clutch, like a freewheel on a bicycle. This is so that if you continue to hold the starter key over after the engine has fired and revved up, the engine cannot turn the starter motor faster than it wants to go. These normally comprise small rollers, ramps and springs - the rollers move up the ramps and jam the inner to the outer when driven the normal way, but on overrun the rollers are pushed back down the ramps a bit and thus don't transmit the drive.

YEs it does! 'Bendix' is a generic term

 

A generic term for a spiral drive to a starter pinion such that when the motor accelerates rapidly, the mass of the pinion resists the acceleration and thus the carrier winds around and hence out, putting the starter pinion in mesh with the engine. The drag from the engine holds it in mesh. Once the engine fires and/or the key is released, a spring pulls the pinion carrier spirally back to where it started.

 

A pre-engage starter system such as the OP has is definitely not a bendix.

Edited by nicknorman
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A few years back i had a boat with a BMC 1.5 that did much the same,i was on the L&L and had just stopped for lunch at one of the lift bridges i removed the starter motor to find the pinion in 3 pieces! luckily i could get my fingers in and retrieve all the bits, went to a local boatyard who had a rusting BMC "out the back" ... they let me have the starter for 25 quid , fitted it and was up and away again.... long shot i know, but worth checking.

 

Rick

 

As well as that with a jump lead to earth it you can at least physically see it is operating if it is out.

Edited by dccruiser
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My suspicion is that the one way (sprag) clutch on the pinion has burst but we will not know until the motor comes off.

 

Now if it was a 2.2 I woudl say slipping multiplate clutch.

 

I wasn't familiar with those clutches in starters until I recently came across a Perkins with one. Everything worked fine, except the pinion didn't turn the engine. So much to learn

 

Richard

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A marine motor mechanic based on the same canal has agreed to come and look - after our afternoon wrapped round the engine we are not confident we've got the tools/arm muscles/know-how to get the starter motor off the engine without damage to either it or (more likely) us. I've assured him that we have done enough tests for it not to be a flat battery = total waste of his time. If the motor pinion clutch is goosed then we'll need someone to source a repair/replacement anyway.

It will be the week after next before he and we have matching dates to get to the boat. I'll post updates for people when there is news.

 

Thank you all again for the expertise, the banter and the general friendliness.

 

Lisa

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Princess Gilly - Dave Craig, yes? We spoke on Friday. Trying to sort out a date!

Bizzard - there's always one isn't there? :-P Do feel free to send your Aunt Mabel but I won't be paying her travelling expenses unless she can do more than just look! :-)

To check out the starter motor and by-pass everything else go direct to it with jump leads. Neg- lead from neg- post on battery to engine mass as close to the starter body as poss. Pos+ lead on pos+ post of battery to large terminal on starter motor solenoid. One of these terminals will make the motor just spin without it engaging with the engines ring gear. If you clamp it onto the other large terminal, the one which the existing pos+ cable from the battery is attached to, you will need another thin wire to connect to it with the other end of it touched to the small terminal next to them, this is the terminal which will energize the solenoid to make the starter work fully and to engage and start the engine. Be careful whilst connecting the jump leads for fear of touching each other or opposite poles and causing big arcing flashes.

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To check out the starter motor and by-pass everything else go direct to it with jump leads. Neg- lead from neg- post on battery to engine mass as close to the starter body as poss. Pos+ lead on pos+ post of battery to large terminal on starter motor solenoid. One of these terminals will make the motor just spin without it engaging with the engines ring gear. If you clamp it onto the other large terminal, the one which the existing pos+ cable from the battery is attached to, you will need another thin wire to connect to it with the other end of it touched to the small terminal next to them, this is the terminal which will energize the solenoid to make the starter work fully and to engage and start the engine. Be careful whilst connecting the jump leads for fear of touching each other or opposite poles and causing big arcing flashes.

 

I wonder if you remember this, Biz?

You can listen to it here: http://www.whistlecr...les/starter.wav

 

 

 

That's something broken around the pinion or ring gear in my book

 

Richard

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Once the starter motor is off the engine you can inspect the pinion mechanism for wear or damage and by plonking the motor on the ground with your boot on it to hold it down, then connect the jump leads and the thin wire to it as my post above. The motor should kick into action powerfully with the pinion whamming forward at the same time jogging your foot with its torque. If the motor has a brush inspection band on it, slide it clear to inspect the brushes for wear and free movement, their curly snail springs and also the commutator.

If you remove the starters rear end cover which holds the brush gear, there is a special (method-knack) of refitting it to get the brushes re-seated, which I will explain how to do if you should remove it.

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  • 1 month later...

Hi All,

I promised an update when I finally got the starter motor problem fixed. Here it is!

Thanks again to Tony Brooks for the diagnostic sequence - which confirmed that it was the starter motor and not just the solenoid.

Thanks to the person who mentioned that Dave Craig was on the Macc - and to Princess Gilly for making the contact.

After several weeks of neither Dave nor us being able to get to the boat at the same time, he came to it yesterday. It was a bit of a <expletives deleted> to get apart (the oil filter has to come off first and the bottom bolt on the starter motor is about a foot longer than it needs to be with very rusty threads!) but yes, the starter was totally seized up. So now we have a working one and the engine started first time despite the (brand new) battery having been sat idle for 9 months. All is now charged, water and oil levels checked and *next* time we go to the boat we'll actually be able to take it out!

Many thanks to Dave - he was brilliant.
Many thanks to folk here for getting me on the tracks to getting it sorted.

Cheers,

Lisa

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