Starter motor click bmc1.8

[Poppin]

I’m really baffled by our starter motor situation and wanted to ask if you have any ideas. Before we left we were just getting a click and no engine turnover. I cleaned all the connections and then it was perfect for a while. A few days into this journey and clicking starts again. I cleaned all connections again and it improved, but today again it’s just clicks. I can start the engine if I run the generator for a couple of mins first and get the voltage up, so again that points to a connection problem, but I can’t figure this out. I’ve even put another cable direct to batt positive to bypass the isolator As I’ve read these can fail. Starter batt is almost new. Do you have any ideas?

[Momac]

3 minutes ago, Poppin said:

 I can start the engine if I run the generator for a couple of mins first and get the voltage up,

Try a different battery.   

Or fully charge the battery .

[Poppin]

4 minutes ago, MartynG said:

Try a different battery.   

Or fully charge the battery .

Makes no difference I’m afraid 

[Momac]

I had similar (not on the same engine) .

In the end it was a corroded electrical connection but you seem to have explored that .

Defective  isolator switch perhaps ?

[Alan de Enfield]

17 minutes ago, Poppin said:

Starter batt is almost new. Do you have any ideas?

 

You can kill a battery in a matter of days.

Are you sure the alternator is charging the starter battery ?

 

What voltage is the starter battery showing 'at rest' and what voltage is it showing when you are trying to turn over the engine ?

 

Check the starter to battery cable and starter to earth cable are both clean and tight.

 

 

Edited April 3, 2022 by Alan de Enfield

[Poppin]

1 minute ago, MartynG said:

I had similar (not on the same engine) .

In the end it was a corroded electrical connection but you seem to have explored that .

That’s interesting. Which connection was corroded and was it visible corrosion? I have tried bypassing the isolator already. 

[Onewheeler]

Could be the contacts in the starter solenoid, with a fully charged battery just giving enough kick to overcome the corrosion. Take the solenoid off if possible (more than one model of starter used I think) and give the contacts a clean with a small file (a nail file is good enough).

[Tony Brooks]

It may well be contacts in the ignition switch and possibly and undersized cable between the switch and the starter. Try a separate bit of cable from start battery positive to the small single connection on the starter solenoid. Alternatively use an old screwdriver between the main solenoid battery connection and that small single terminal. Be positive and take care not to short the screwdriver to any metal. If that works every time then it is probably the ignition switch. This assumes that thin solenoid wire does not feed the solenoid via a relay.

30 minutes ago, Onewheeler said:

Could be the contacts in the starter solenoid, with a fully charged battery just giving enough kick to overcome the corrosion. Take the solenoid off if possible (more than one model of starter used I think) and give the contacts a clean with a small file (a nail file is good enough).

 

Only any good if:

A. the solenoid cap is secured by screws and no swaged.

B. the OP has the equipment and knows how to de-solder the relay coil connection son the cap, can re-solder them, and takes great care to refit the cap correctly.

[Poppin]

12 minutes ago, Tony Brooks said:

It may well be contacts in the ignition switch and possibly and undersized cable between the switch and the starter. Try a separate bit of cable from start battery positive to the small single connection on the starter solenoid. Alternatively use an old screwdriver between the main solenoid battery connection and that small single terminal. Be positive and take care not to short the screwdriver to any metal. If that works every time then it is probably the ignition switch. This assumes that thin solenoid wire does not feed the solenoid via a relay.

But doesn’t the clicking indicate the solenoid is closing and making contact? Surely if it was ignition positive not getting through there would be no click? Is that wrong? 

[Jen-in-Wellies]

What system does your boat use to ensure charging of the house and starter batteries? One alternator, or two? Multiposition battery isolator switch? Voltage sensitive relay? Diodes?

 

[Poppin]

2 minutes ago, Jen-in-Wellies said:

What system does your boat use to ensure charging of the house and starter batteries? One alternator, or two? Multiposition battery isolator switch? Voltage sensitive relay? Diodes?

 

Single alternator to house batts, VSR to starter. Also solar to house batts. I have measured amps going into starter batt from both. I’m pretty sure starter is fine. 

[Tony Brooks]

13 minutes ago, Poppin said:

But doesn’t the clicking indicate the solenoid is closing and making contact? Surely if it was ignition positive not getting through there would be no click? Is that wrong? 

 

You can't think in terms of the electricity getting through or not getting through.You also have to consider how resistance reduces current flow and thus limit the strength of the solenoid magnets.

 

Yes it can be wrong, all the click means is the solenoid has moved and something has been hit, this could be the pinion kissing the end bracket/flywheel tooth or the contacts, but that does not mean the contacts have actually made contact. just to complicate the issue the moving contact bar has a spring on it that will attempt to push the contacts out of contact. That is fine as long as the solenoid is properly energized. If there is volt drop on the solenoid feed the solenoid coils may not exert enough force for the contacts to make good contact.

 

Just to complicate the matter solenoid pull in coil goes to negative via the motor brushes and armature so  poor brush contact might give the symptoms, but if the thing starts OK once the motor turns this is far less likely.

[ditchcrawler]

47 minutes ago, Tony Brooks said:

It may well be contacts in the ignition switch and possibly and undersized cable between the switch and the starter.  

This is a problem I had and fitted a relay on the starter solenoid, The previous owner had one fitted there as well but I removed it. 

[Onewheeler]

1 hour ago, Tony Brooks said:

Only any good if:

A. the solenoid cap is secured by screws and no swaged.

B. the OP has the equipment and knows how to de-solder the relay coil connection son the cap, can re-solder them, and takes great care to refit the cap correctly.

It depends on the model. On my long dead BMC the contacts could be removed with the end of the casing with a couple of screws once the big cables have been disconnected. Can't remember the details but no soldering needed.

[Tony Brooks]

24 minutes ago, Onewheeler said:

It depends on the model. On my long dead BMC the contacts could be removed with the end of the casing with a couple of screws once the big cables have been disconnected. Can't remember the details but no soldering needed.

 

I have never seen a per-engage starter solenoid that had mechanical fixings for the solenoid coil wires, all were soldered to the energize terminal on the cap and a metal plate under the link terminal to the motor itself.  Yes to the two screws.

 

I can't work out any other way of doing it without much expense and the likelihood of greater unreliability.

[Onewheeler]

18 minutes ago, Tony Brooks said:

 

I have never seen a per-engage starter solenoid that had mechanical fixings for the solenoid coil wires, all were soldered to the energize terminal on the cap and a metal plate under the link terminal to the motor itself.  Yes to the two screws.

 

I can't work out any other way of doing it without much expense and the likelihood of greater unreliability.

I can't remember the ins and outs, but undoing the two or three screws on the end cap enabled access to the big bit of springy copper or brass which could have the contact points filed clean. I think the big bit of springy metal came out with the end cap, but it was twenty years ago...

[Tony Brooks]

2 minutes ago, Onewheeler said:

I can't remember the ins and outs, but undoing the two or three screws on the end cap enabled access to the big bit of springy copper or brass which could have the contact points filed clean. I think the big bit of springy metal came out with the end cap, but it was twenty years ago...

 

I have no idea what you are describing. The springy metal makes it sound like a relay to me, not the solenoid. The solenoids have a literal bar of copper that is in no way springy. The solenoid armature pushes this bar against the heads or the two copper "bolts" that form the two main connection terminals.

 

I think the end/contact cover on an axial starter is held on with just  two screws so can just be taken off but the small BMCs never fitted such starters.

[Onewheeler]

4 minutes ago, Tony Brooks said:

 

I have no idea what you are describing. The springy metal makes it sound like a relay to me, not the solenoid. The solenoids have a literal bar of copper that is in no way springy. The solenoid armature pushes this bar against the heads or the two copper "bolts" that form the two main connection terminals.

 

I think the end/contact cover on an axial starter is held on with just  two screws so can just be taken off but the small BMCs never fitted such starters.

It's the part that makes contact for the high current to the starter motor. Very crude when it was dismantled. Yes, a relay.

[Tony Brooks]

The part that makes contact for the high current on per-engage starters as per the1.5 & 1.8 is a copper bar as I described. You will also find contractors and remote inertia starter solenoids use a similar arrangement. Nothing is springy in the contact parts.

 

You would not use a relay to switch the high current because it would melt.

 

Some people use a relay close to the starter to overcome volt drop on the solenoid energies cable or to make the ignition switch last longer. That may be what you took apart. Access to the contacts on an inertia starter solenoid can usually be gained just by removing screws without soldering but if so it will be remote from the starter and have nothing to do with the high currant circuits.  This is a BMC headed topic so we can ignore the use of this type of solenoid on certain lister engines that makes them a sort of fully insulated return.

 

Anyway as long as the OP gets the idea that is is not as simple as removing two screws to gain access to the contacts all is well. For most boaters fitting a new solenoid would be easier.

[Tony Brooks]

I found this image and have shown the two solder pads that need un-soldering to get the cap off.

 

 

[Onewheeler]

Nope, that's very different to mine. Must have been an odd one.

 

[Slim]

On 03/04/2022 at 12:26, Poppin said:

I’m really baffled by our starter motor situation and wanted to ask if you have any ideas. Before we left we were just getting a click and no engine turnover. I cleaned all the connections and then it was perfect for a while. A few days into this journey and clicking starts again. I cleaned all connections again and it improved, but today again it’s just clicks. I can start the engine if I run the generator for a couple of mins first and get the voltage up, so again that points to a connection problem, but I can’t figure this out. I’ve even put another cable direct to batt positive to bypass the isolator As I’ve read these can fail. Starter batt is almost new. Do you have any ideas?

I still think it could be a battery issue . After an abortive attempt to start and before any attempt to do anything else what's the battery voltage?

Edited April 4, 2022 by Slim

[Slim]

4 minutes ago, Slim said:

 

 

[Tony Brooks]

26 minutes ago, Slim said:

I still think it could be a battery issue . After an abortive attempt to start and before any attempt to do anything else what's the battery voltage?

 

It could well be. Far too many people believe if the magic eye is green the battery is fine. I am amazed that when you asked for the battery voltage it was not given because that is the next step in diagnosis after hand, eye and nose tests on the circuit. After that we are just trying to make informed guesses and give some diagnostic steps.

[Alan de Enfield]

11 minutes ago, Tony Brooks said:

 

It could well be. Far too many people believe if the magic eye is green the battery is fine. I am amazed that when you asked for the battery voltage it was not given because that is the next step in diagnosis after hand, eye and nose tests on the circuit. After that we are just trying to make informed guesses and give some diagnostic steps.

 

 

I asked for the battery voltage in the 4th post, but it appears to have either been ignored or thought to be a waste of time answering because ..........

 

 

On 03/04/2022 at 12:26, Poppin said:

Starter batt is almost new

 

 

Makes you wonder why you bother trying to to help.