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Help! Need someone to look at my starter motor!


Mayflower
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Hello All,

 

Not sure if I should be here with the specialists - do feel free to boot me out onto the general lists if I'd be better there.

 

I've got a 1981 boat on the Macclesfield Canal near Poynton. BMC engine. After a massive amount of work including a total re-build of the engine compartment requiring the removal and re-installation of the engine, the boat was returned to its moorings by the boat repairer under its own power. The next time we tried to start it, with the repairer present, it wouldn't - but we were all in a rush to turn it round and we just hauled it with ropes without much thought assuming flat battery (despite, with hindsight, it not making the right sound for that!). Pretty certain this is a starter motor issue. Reluctant just to clump it with a rubber hammer as everything is supposedly now beautifully aligned and I don't even know if that starter motor has a bendix (I used to have to do this on two of my old cars in my youth). The person who did the work is no longer available - we were his last job and he is now longer in the area, possibly no longer in business, through no fault of his own.

 

Can anyone recommend an engine engineer or maintanace or repair person who could come out to the boat and advise? I was hoping my days of pulling engine bits apart were long over. It's a lovely clean boat and could be a simple job for someone who knows what they are doing.

 

Any recommendations?

 

Please!!!

 

Ta,

 

Mayflower

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Sorry no use for an engineer but easy to check yourself as very little to a starter motor, could save a fortune aswell if you fettle it yourself, and as said by bloomsbury, is there a click or click, could start by seeing if there is power and how much to the starter with a cheap volt gauge, this will tell if there is power and enough. If its knew it should be fine, if anything jammed.

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No they do not use a Bendix as such, they use a solenoid to pull the drive sprocket and one way clutch into mesh with eh flywheel and the turn the motor on.

 

As has been said we need a much fuller description of the sound(s) it makes, what it does and does not do, and what the battery voltage is while trying to crank (that is measured at the battery, not on some random connected volt meter). An estimate of starter motor temperature immediately after cranking would help as would the temperature of your master switch(es).

 

At present it could be almost anything so guessing without knowing the symptoms will not do.

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Thank you all! Yes, it definitely goes click and it sort of groans a bit almost as if the battery is dead (but it isn't). This from memory - I'm going back to the boat on Thursday and will do proper tests as per Tony's suggestions and also make a more accurate description of the sound. Sorry - it's been a while since I tried it - had some other non-boat stuff to deal with. Encouragement to resurrect my diagnostic skills (and then, if necessary my taking things apart skills) much appreciated. More sensible reply when I've been back to the boat (with a decent DVM).

 

Lisa/Mayflower

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Thank you all! Yes, it definitely goes click and it sort of groans a bit almost as if the battery is dead (but it isn't).

 

 

The question that leaps to mind is how do you know the battery isn't dead? A click and a sort of groan is classic 'flat battery' symptoms!

 

Hence Tony's question about battery voltage whilst trying to turn the engine over.

 

Could equally be a poor cable connection or a high resistance isolator switch.

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If the engine has had an overhaul maybe the guys burnt out the starter motor cranking it over for to long,

Check the power at the starter/solenoid terminals on cranking and check the earth strap
Knock hell out of the Solenoid

Other than that I would take it off and take it to an Alternator/Starter Motor Refurb place such as this one in Stockport only 5 miles or so from where you are

That Solenoid Click is normally just a Low Battery but not always, maybe borrow a Battery from a fellow Boater and rule that out.

 

http://www.robinsonrewinds.co.uk/

Edited by grumpy146
  • Greenie 1
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A Solenoid click could be a low battery but can also be a bad connection.

 

Taking voltage readings at various locations during cranking can verify this and is an easier and quicker method.

 

If you are unsure is there anyone you know who can help you with this ?

Edited by Bloomsberry
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Voltage readings now definitely required because the click suggests the solenoid is operating, the groan suggests the solenoid contact are closing but for some reason the starter is not turning over properly. The possibilities from that sequence of symptoms roughly in order of likelihood are:

 

1. Flat battery

2. Dirty battery terminals.

3a. Burned contacts in the solenoid.

3b. Faulty battery master switch.

4. Worn/sticky brushes in starter

5. Short circuit in starter (but the motor would get warm/hot).

 

Voltmeter test sequence, each test done while operating the starter. Set to 20 volts DC unless its a 24 volt boat. If so set to 200 volts DC.

 

First try turning the engine over by hand. It will have a couple of stiff spots every turn as it comes on the compression strokes but it should have some fairly easy section. If it is all difficult or it will not turn the engine is seized or the motor is jammed in mesh.

 

NOTE - a short in the starter or a jammed starter would produce "fault figures" but the motor body would get warm/hot to the touch.

 

1. Voltmeter across battery lead post to lead post. Expect 12V + dropping to 10V minimum. as you operate the starter. That is a Lucas figure, I would accept 9V+ at this stage. Less that that = a discharged or faulty battery.

 

2. Voltmeter across the metal battery clamps, expect the readings obtained above with a reduction of (say) 0.3 volt while cranking. A higher reduction = dirty battery terminals. Remove, clean and dress with Vaseline

 

3. Meter across the master switch terminals - only take reading while cranking. Expect all but zero volts. More than about 0.5 indicates dirty/faulty internal contacts.

 

4. Meter across the two large nut & stud terminals on the starter - only take reading while cranking. Expect all but zero. More than about 0.5 = faulty solenoid contacts.

 

To check the wires and terminals:

 

5. Meter between battery negative and the starter body (scrape paint away) or starter negative terminal - only take reading when cranking. Expect less than 0.25 (Lucas figure) but I would accept a LITTLE higher. Anything much higher indicates undersized cables or faulty cable to terminal connection(s).

 

6. Meter between the battery positive terminal and the main battery lead terminal on the solenoid - only take reading while cranking. Expect less than 0.5 volt (Lucas figure) more indicates undersized cables or faulty cable to terminal connections.

 

 

7. If all the above are in spec. and the starter body remains cool then it is an internal brush problem so a good whack with a shoe heel, rubber/wooden mallet or at a pinch a good tap with the mooring hammer may free it enough to start. This is not to be undertaken on any modern starter than uses permanent magnet field coils.

  • Greenie 2
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Thank you! The battery was brand new after the refit - and the first failure was only a few weeks after - even our old battery went longer than that between starts so I really don't think it was the battery then (even if it is now) - open circuit voltage on the meter for the battery was over 12V. Before the refit we had some years of sluggish starting and the engine would at least try to turn - this feels and sounds different. Anyway I've now got lots to try and I'll report back after tomorrow!

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I had an odd one on a pals diesel car last week. Turn the key and it was clicking. Checked battery and connections and all good with lots of volts. Decided it was the starter.Was about to order one when I decided to try jump leads but still clicking. As I had a good battery handy I decided to try that. Started first time. It seems that a multimeter reading good volts does not guarantee a good battery.

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I had an odd one on a pals diesel car last week. Turn the key and it was clicking. Checked battery and connections and all good with lots of volts. Decided it was the starter.Was about to order one when I decided to try jump leads but still clicking. As I had a good battery handy I decided to try that. Started first time. It seems that a multimeter reading good volts does not guarantee a good battery.

 

Of course it does not. That is why the list I gave above makes the tests while trying to crank.

 

 

Thank you! The battery was brand new after the refit - and the first failure was only a few weeks after - even our old battery went longer than that between starts so I really don't think it was the battery then (even if it is now) - open circuit voltage on the meter for the battery was over 12V. Before the refit we had some years of sluggish starting and the engine would at least try to turn - this feels and sounds different. Anyway I've now got lots to try and I'll report back after tomorrow!

 

May I point out that a rare but possible problem on a new battery is that a cell interlink is not properly made. This fault can give excellent open circuit readings abut they collapse as soon as a decent load is placed on the battery.

 

It could be brushes now you add the sluggish for some years information so do not be afraid to give the motor body a sharp whack. It has wound fields so will not do any damage (as long as you do not miss and hit the solenoid!)

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I am having this funny internal feeling that the engine room rebuild may have left a negative wire dis or mis-connected but that is a guess and should not be acted upon. The voltdrop test between battery neg and the starter case (test 5) will give several volts reading if this is the fault.

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I am having this funny internal feeling that the engine room rebuild may have left a negative wire dis or mis-connected but that is a guess and should not be acted upon. The voltdrop test between battery neg and the starter case (test 5) will give several volts reading if this is the fault.

 

The earth strap, for instance. It would be worth checking as it would give exactly the symptoms described

 

Richard

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Right - the Meter Maid is back!

 

Did a few things before starting methodically through Tony's list.

 

1. (to check the analogue voltmeters in the boat) Battery voltage shown by on-board meter before cranking 13V. While cranking (or at least trying to) 10.2V

 

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

 

3. The starter motor does not get hot.

Then worked through Tony's List with the following results (all well within spec).

 

 

1. Voltmeter across battery lead post to lead post. Expect 12V + dropping to 10V minimum. as you operate the starter. That is a Lucas figure, I would accept 9V+ at this stage. Less that that = a discharged or faulty battery.

 

12.36V dropping to 10.46V

 

2. Voltmeter across the metal battery clamps, expect the readings obtained above with a reduction of (say) 0.3 volt while cranking. A higher reduction = dirty battery terminals. Remove, clean and dress with Vaseline

 

2.305V dropping to 10.40V

 

3. Meter across the master switch terminals - only take reading while cranking. Expect all but zero volts. More than about 0.5 indicates dirty/faulty internal contacts.

 

Didn't do this - required either the person squeezed in around the engine to wriggle out again or the meter-reader to grow VERY long arms. Decided to come back to this only if the readings further down the chain were out of spec. If not - the switch should be OK, yes?

 

4. Meter across the two large nut & stud terminals on the starter - only take reading while cranking. Expect all but zero. More than about 0.5 = faulty solenoid contacts.

 

0.12V

 

To check the wires and terminals:

 

5. Meter between battery negative and the starter body (scrape paint away) or starter negative terminal - only take reading when cranking. Expect less than 0.25 (Lucas figure) but I would accept a LITTLE higher. Anything much higher indicates undersized cables or faulty cable to terminal connection(s).

 

0.32V - and we didn't scrape the motor body which isn't painted but which has a patina of probably non-conductive age.

 

6. Meter between the battery positive terminal and the main battery lead terminal on the solenoid - only take reading while cranking. Expect less than 0.5 volt (Lucas figure) more indicates undersized cables or faulty cable to terminal connections.

 

Variable between 0.48 and 0.5

 

So it looks as if the (new) wiring is as sound as it looks.

 

7. If all the above are in spec. and the starter body remains cool then it is an internal brush problem so a good whack with a shoe heel, rubber/wooden mallet or at a pinch a good tap with the mooring hammer may free it enough to start. This is not to be undertaken on any modern starter than uses permanent magnet field coils.

 

All above were in spec and the motor body remained cool. I was the meter reader, the other half of the team had volunteered to be the one in the engine. He wallopped it gently with a rubber hammer (it's hard to wallop it harder than gently as there is very little room around the motor and some fuel-providing parts immediately by it (see later). This had no effect, after two lots of gentle whacking. Dug out metal mooring pin hammer and tapped it with that (again no room for a decent swing to give a sharper whack, even if we had the nerve). Also no effect.

Tried to take the aluminium end cover off to see if we could get at the brushes but the fuel supply gubbins prevents it coming off. So it looks as of we're gonna have to take the entire starter motor off - which is NOT going to be straightforward as, of the three long bolts that hold it on, the one at the bottom that we can't see is loose - which probably means it's got a seized-up cross-threaded nut somewhere where we can't see!

 

We called it a day at that. Will have to go back, obviously but away in the Midlands next week.

Thank you for the diagnostic sequence and figures. Looks like 'duff starter motor' - oh bliss!

 

Lisa

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As the engine has been in and out I also get a funny feeling about this one. As someone has already suggested the earth strap, are we sure the negative side cables haven't been pinched or stretched? It could result in broken strands thus resulting in poor cranking amps, I would expect this to result in local cable overheating though.

 

You say this engine has been rebuilt, did this mean the ring gear was disturbed? Or changed? I'd drop the starter motor and inspect the gear also the pre-engaged starter gear. I suspect partial jam.

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The engine compartment was rebuilt - the engine had to come out and then go back in but wasn't itself rebuilt. All the wiring is new and very good (the previous was an incomprehensible rat's nest). The boat started at least once after the rebuild - for the rebulder to return it to us. The problem emerged the next time we tried to start it - about a month later.


Gotta go to bed now - I'll be back in the morning (late morning!)

Lisa

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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

 

 

Ok, that's the sound of a starter motor spinning up with no load on it, i.e. the pinion has failed to move forward and engage with the ring gear on the flywheel.

 

Can be caused by low battery voltage, starter motor fault, wiring fault. When the motor is running but with no load, I'd expect the battery voltage not to drop much. Yours drops to 10.46v according to your results. This suggests a crap battery to me but Tony might disagree.

 

Also, the voltage of 0.32v between negative battery terminal and starter motor body is FAR too high given the 'no load' conditions you are measuring under. This suggests to me the 'earth strap' is not making connection and the motor current is flowing along the Morse control cable etc.

 

This 0.32v gets subtracted from the already low battery voltage of 10.4, as does the 0.5v drop you recorded across the positive side, meaning the the starter motor is seeing about 9.7v whilst attempting to crank. Probably too low to get the pinion to engage.

 

Should the starter actually engage with the flywheel and do so work, I'd expect either the battery voltage to drop substantially further, or the battery terminal/starter body value to rise significantly. As the next step I'd double check the earth strap and negative battery cable connection at both ends, and all the positive cable connections in an attempt to reduce those values (and fully charge the battery) in an attempt to get the motor engage the flywheel, then re-measure all those values Tony asked you for.

 

If the starter pinion gear still won't move forward to engage the flywheel, I think it's time to take the starter motor off and off to a rebuilder.

Edited by Mike the Boilerman
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