Intermittent starter problem?

[MattW]

'94 1100

Out for a ride yesterday and a couple of times when I tried to start the engine it just clunked and wouldn't turn over. On each occasion, I released the button, pressed again and it spun over as normal and started.

There was no noise or graunching on the occasions it wouldn't start - just the usual solenoid clunk. It just felt like the starter wouldn't turn the engine over compression - almost like the battery was flat (but then it would on the next attempt)? It happened on a stone cold and a hot engine and only on a couple of occasions out of say 6 or 7 normal starts.

Battery two years old and healthy and I had the starter to bits last year to check the magnets and everything was fine.

Any ideas?

 

[DollyRocket]

Check all connections (power) are tight.
Check starter motor relay (possibly swap for another)
Check battery volts with starter motor running
Then check starter again.

 

[MattW]

Check all connections (power) are tight.
Check starter motor relay (possibly swap for another)
Check battery volts with starter motor running
Then check starter again.

Thanks - I'll have a look today

 

[John Armstrong]

Especially check the battery leads are done up properly, DAMHIK

 

[MattW]

Ok, done some checking.

All connections secure.

Battery volts at rest: 12.9

Battery volts while cranking: 10.3

However, it did its 'not turning over' thing a few times while I was just testing it and when it refused to spin over, there was the clunk of the solenoid and a bit of a metallic clang but the battery volts didn't drop.

Does this mean that the starter gear is failing to engage with the flywheel (the 'clang') and hence isn't closing the circuit to power up the motor?
If so, any ideas what might be the cause of this?

thanks
Matt

 

[autogs]

have you actually removed the starter?
do you go offroad?
if so check for crud compacted in the housing.

 

[MattW]

have you actually removed the starter?
do you go offroad?
if so check for crud compacted in the housing.

Took the starter apart a year ago to check the magnets - all fine - cleaned , greased and reassembled.

I don't off road

I guess next job is to remove the starter and look for problems?...

 

[MattW]

Starter removed.

Flywheel gear looks fine (and no oil in there which is always nice to see ):

<a href="https://picasaweb.google.com/lh/photo/ZaXNJwz2giUT3lRhguppt0OOAeJkWHiivqDz0FeWdvU?feat=embedwebsite"><img src="https://lh6.googleusercontent.com/-TA4x7kpyTfo/TetsvQBBoKI/AAAAAAAAE_0/Q_AxeVkc8qg/s800/IMG_5873.JPG" height="800" width="600" /></a>

The starter gear looks ok but lots of clutch dust in there - I'm wondering if it might be slightly sticking on the shaft and failing to engage...

<a href="https://picasaweb.google.com/lh/photo/B2bYzFrIm0CNpYjEco8LN0OOAeJkWHiivqDz0FeWdvU?feat=embedwebsite"><img src="https://lh4.googleusercontent.com/-1Xkl7IjeBZg/Tetsxar7I3I/AAAAAAAAE_4/GxfXeItwfuE/s800/IMG_5875.JPG" height="600" width="800" /></a>

I've split the starter and the magnets are still firmly stuck.

Wondering how tricky it is to dismantle the solenoid / gear end of the motor and give it a through clean / lube? I don't want one of those "sproing - bits all over the garage" moments

 

[MattW]

Right - bull seized by horns and solenoid 'end' removed from casing.

The gear assembly was quite sticky on the shaft - I've attacked it with brake cleaner and it now slides a lot more freely.

I'm unfamiliar with the workings of starters but the chunk item circled in red below appears to be some sort of one way clutch (I assume so that the starter won't be 'driven' by the engine when it starts). It feels quite rough in its 'freewheel' direction - anyone know if this is normal? I can't see any obvious way to strip and check it?

<a href="https://picasaweb.google.com/lh/photo/k6wRWNZCleA7cxsCwhyKdEOOAeJkWHiivqDz0FeWdvU?feat=embedwebsite"><img src="https://lh6.googleusercontent.com/-wNh08WIGQZw/Tet6eXFtV4I/AAAAAAAAFAI/vgt6OZVQGKA/s800/IMG_5877edit.jpg" height="600" width="800" /></a>

 

[MattW]

Continuing to talk to myself - good therapy if nothing else

Cleaned and greased the sliding bits of the starter motor, reassembled and pressed the starter button. No response at all - wouldn't even trigger the solenoid I turned it off and on a couple of times and then it did its clunking but not turning over trick. A couple more presses of the button and it started to turn over again.

As I was looking at the dash this time, I noticed that on the occasions that it wouldn't turn over, the fuel level indication on the RID blanked. So I guess it's definitely electrical rather than mechanical.

I removed and reseated the starter relay and waggled various bits of loom I could get to and the next few presses the starter worked as it should.

So, I'm a bit stumped - I guess I'll replace the starter relay and see what happens

 

[Pekkavee]

I'm unfamiliar with the workings of starters but the chunk item circled in red below appears to be some sort of one way clutch

It is Bendix. It engages the starter with the motor and then lets it run after start.
Bendix images
It can slip.
I had the same problem few weeks ago.

You can test it this way.
Take the spark plugs out.
If the motor turns with the starter with no spark plugs, it's the Bendix.

The only way to cure it is to buy a new starter.
BMW does not sell any new Bendix parts. Or not any other either.

Here you can find a cheap starter. I bought one. And it's working fine.
New starter 58.- euros

BTW. The starter is made by Valeo. Valeo type in BMW is Valeo D6RA 75 or 55. The same starter is used in many Citroen and Peugeot cars.
BUT ;o(
BMW starter runs in other direction ( CCW ) and has only 9 teeth in Bendix gear wheel. Cars have 10 teeth. So Peugeot parts will not work. They sell Bendix as a spare part.

Pekka

 

[slimbo]

if the solenoid is actuating but the motor does not operate then you need to check the solenoid itself as a build up of muck will prevent the power from being switched and the motor dont operate!!

also check the feed from the solenoid to the actual motor as this is a common place for stuff to not work!!!

 

[Pekkavee]

Hmmm..

Maybe the right word is to rotate
"If the motor turns with the starter with no spark plugs, it's the Bendix."
Maybe I turn in my bed tonight when thinking of this.
I can not imagine how the motor would turn upside down.

So it should be maybe
"If the motor rotates with the starter with no spark plugs, it's the Bendix."

Sorry for my english.
Pekka

 

[Stewart H]

The front end of the starter should be cleaned with solvent and blown dry, any lubricant there will only attract clutch dust and cause trouble like you have, a dab of grease on the front bearing and a bit on the reduction gears is good but the "bendix bit should be dry

 

[fatnfast]

I take it the brushes are all ok? Well worth a check. If you have had the motor apart before, including the brush gear, its very easy to crack the brush holder on reassembly. This in turn could effect the spring tension applied to the brushes.

 

[MattW]

Hmmm..

Maybe the right word is to rotate
"If the motor turns with the starter with no spark plugs, it's the Bendix."
Maybe I turn in my bed tonight when thinking of this.
I can not imagine how the motor would turn upside down.

So it should be maybe
"If the motor rotates with the starter with no spark plugs, it's the Bendix."

Sorry for my english.
Pekka

Thanks Pekka - believe me - your English is a great deal better than my Finnish

The front end of the starter should be cleaned with solvent and blown dry, any lubricant there will only attract clutch dust and cause trouble like you have, a dab of grease on the front bearing and a bit on the reduction gears is good but the "bendix bit should be dry

Thanks Stewart - I did wonder about the advisability of lubing the bendix (as I now know it's called ) so I used a dryslide moly product designed for gun slides - it's basically moly particles in a solvent suspension - the solvent evaporates leaving the dry molybdenum in place.

I take it the brushes are all ok? Well worth a check. If you have had the motor apart before, including the brush gear, its very easy to crack the brush holder on reassembly. This in turn could effect the spring tension applied to the brushes.

Good point - I recall it being a bit of a mare getting the brush holder reassembled and back into place but I think I got it done with no breakages. However well worth a check as you say. I'll remove it and have a look tonight.

thanks everyone for the advice

 

[Norfolk Tiger]

Starter removed.

Flywheel gear looks fine (and no oil in there which is always nice to see ):

<a href="https://picasaweb.google.com/lh/photo/ZaXNJwz2giUT3lRhguppt0OOAeJkWHiivqDz0FeWdvU?feat=embedwebsite"><img src="https://lh6.googleusercontent.com/-TA4x7kpyTfo/TetsvQBBoKI/AAAAAAAAE_0/Q_AxeVkc8qg/s800/IMG_5873.JPG" height="800" width="600" /></a>

The starter gear looks ok but lots of clutch dust in there - I'm wondering if it might be slightly sticking on the shaft and failing to engage...

<a href="https://picasaweb.google.com/lh/photo/B2bYzFrIm0CNpYjEco8LN0OOAeJkWHiivqDz0FeWdvU?feat=embedwebsite"><img src="https://lh4.googleusercontent.com/-1Xkl7IjeBZg/Tetsxar7I3I/AAAAAAAAE_4/GxfXeItwfuE/s800/IMG_5875.JPG" height="600" width="800" /></a>

I've split the starter and the magnets are still firmly stuck.

Wondering how tricky it is to dismantle the solenoid / gear end of the motor and give it a through clean / lube? I don't want one of those "sproing - bits all over the garage" moments

Hi there looking at the picture the clucth dust on the shaft may well be the problem restricting the movement we repair a lot of valeo starters off cars and if they look like that they can give the fault you are describing.I have checked the part no mentioned d6ra 55 & 75 they don't list a drive assembly.If the brush gear was worn this could also give the same fault.To check if power is getting through the solenoid its best done on the bike as follows check voltage on the battery supply to solenoid make sure it remains good when operating,then check if you have good battery voltage coming from the solenoid to the motor lead.

 

[MattW]

Hi there looking at the picture the clucth dust on the shaft may well be the problem restricting the movement we repair a lot of valeo starters off cars and if they look like that they can give the fault you are describing.I have checked the part no mentioned d6ra 55 & 75 they don't list a drive assembly.If the brush gear was worn this could also give the same fault.To check if power is getting through the solenoid its best done on the bike as follows check voltage on the battery supply to solenoid make sure it remains good when operating,then check if you have good battery voltage coming from the solenoid to the motor lead.

Thanks for the help

 

[MattW]

Well....
I'm starting to think that my intermittent starting issue is an electrical fault rather than anything to do with the starter.

I took the starter off again today and checked the bushes - all fine.

But I did some more electrical tests...

It 'fails to turn over' in two different ways:

1. The starter does nothing at all when the button is pressed but in this failure mode (for want of a better phrase ) the fuel level indication on the RID drops to zero and the fuel pump re-primes. This happened more today.

2. The solenoid clunks when the button is pressed but doesn't spin the engine over This happened less today.

There also seems to be a permanent live at the solenoid trigger wire when the ignition is on (the black wire attached to the spade on the solenoid). I don't understand this at all - I thought this only goes live when the button is pressed and the starter relay is energised

Ideas:
The only way I can imagine the RID and fuel pump interacting with the starter button as in (1) above is through a dodgy earth - possibly the big junction near the head stock that I think I've read about?

Dodgy starter button?

Something else - who the feck knows?

 

[MikeO]

Hi there,

Do you have an alarm/immobilser fitted? I took ages tracking down a fault in my immobiliser, that was disabling both my starter and fuel pump intermittently (Meta standard BMW alarm) - your symptoms don't sound dissimilar.

I removed the whole thing and threw it in the bin...

Mike