Any thoughts; intermittent starter issue.

[ianc1200]

I ran my boat a couple of hours, and through two locks on the upper Thames yesterday. In the second lock the engine wouldn't start, but turned over and made a loud clicking noise.
Luckily I have a small wing engine (it's an old boat...) so could get back to the boatyard. The engineer is away this week but his assistant came to listen. The engine turned over in brief stop/starts, putting my hand on the starter motor/solenoid I couldn't feel that the clicking was coming from there. I asked them to have a look at it, and when I went this morning to drop off a spare starter I happen to have they reported it started OK, no noticeable problem. They had intended to take the starter off to look for any obvious problems.
I noticed yesterday when arriving back the starter battery was at 12.7V which I thought was low - after such a run would have expected 13.1V or similar. The battery was new May 2019. For completeness the engine is a 2008 Nanni 62hp 5 cylinder.
I think there's a battery issue, or connections, rather than the starter. Although a weak battery would surely turn it over slowly, but continuously? I'm also wondering if the situation is altered whether the engine is cold (hence starting several times this morning) or hot (and failing more times yesterday to start). I can change the starter & the battery fairly easily, and have all day Thursday to look for faults, any other suggestions?

 

[Paulg25]

12.7 volts is normal for a fully charged 12v lead acid battery. Sounds like a bad connection somewhere. Is the solenoid separate from the starter?

 

[mrangry]

The clicking noise will have been the solenoid engaging and my guess is either low battery or poor connections

 

[[70521]]

Like others have said 12.7 volts is a full battery at rest. Worth checking all the connections.

 

[Plum]

the engine wouldn't start, but turned over.

When you say the engine turned over , do you mean the starter was working correctly, turning/cranking the engine at the normal speed but just stopped and started, or was it turning slowly and erratically?

 

[ianc1200]

When you say the engine turned over , do you mean the starter was working correctly, turning/cranking the engine at the normal speed but just stopped and started, or was it turning slowly and erratically?

A bit between the two. Certainly turned it over, perhaps not as fast as usual, but stopping and starting rapidly. A pity I didn't film it.

 

[jiris]

A bit between the two. Certainly turned it over, perhaps not as fast as usual, but stopping and starting rapidly. A pity I didn't film it.

While a poor connection (battery terminal as a prime suspect) can't be dismissed completely, I wouldn't dismiss a poor battery condition either. Measuring its voltage on open circuit is meaningless. You have to check the voltage under load with a battery tester. If not available, use the highest load you have available - like a search light for instance.

 

[ianc1200]

I have a drop test meter so can check that. I think my main problem is if it continues to work making finding a fault more difficult. I've convinced myself that the fault is in the connections, but will be open minded about it.

 

[mikegunn]

Starter solenoids are basically lazy beasts and need a good sharp shock of enfettered elctricity to spur them into action. Unfortunately, on boats that electricity supply has had to find its way from the battery, up to the starter switch in the cockpit and back down to the engine's starter. That's fine when everything is new, but with the passage of time accumulated points of resistance, such as switch contacts and various connectors, conspire to impede the flow of electricity resulting in a bit of a clunk from the solenoid, but no further action. One remedy would be to replace all the associated wiring and starter switch but, in my opinion a preferred solution is to use the existing wiring to activate a 12V /40 Amp relay which should be mounted as close as possible to the starter solenoid. Cabling from the engine battery to relay and relay to starter solenoid should be capable of carrying 20 Amps. Your local Halfords will have all the necessary bits and pieces and the fix won't break the bank either.
Mike

 

[Plum]

I have a drop test meter so can check that. I think my main problem is if it continues to work making finding a fault more difficult. I've convinced myself that the fault is in the connections, but will be open minded about it.

The fact that the fault is intermittent tells me it is not the battery. Starter motor brushes when they are very worn can give temperamental faults but very unlikely to be worn on a 2008 boat engine. Given that at present it is working I would do the following; 1) clean all the fat cable connections between battery and starter motor solenoid and the earth return from engine to battery, including isolation switches. 2) with some new (2 square mm)wire connect to the fat cable where it is attached to the starter solenoid, then to a push button switch not far away but somewhere you can reach in a hurry, then to the small terminal on the solenoid that activates the starter.

With item 2 you have bypassed all the existing low current wiring so now if the problem happens again, just press that button to see if the engine starts correctly. I have this switch as a permanent feature in Plum's engine compartment. If this extra switch makes no difference, then, and only them, change the starter motor for your spare.

All the above can be done at minimal cost and will be a big help in diagnosing the fault.

www.solocoastalsailing.co.uk

 

[Talmine]

We had a similar problem some years ago and eventually traced to faulty battery cable which had 12.7 volts at one end and less than 10 at the other. Both ends looked fine but when I cut into the cable it was full of verdigris.

 

[Norman_E]

I had a car that did something similar and it proved to be a poor earth connection to the starter motor that was the cause.

 

[vyv_cox]

I had to laugh ironically when I saw the thread title. My motorhome is currently at an auto-electrical shop where the highly recommended owner is scratching his head after a couple of days of testing. There is absolutely nothing wrong with the high current side, he has drop-tested everything, replaced the (faultless) earth connection, checked battery and cable connections (nothing wrong with them). The starter motor works perfectly using the old dodge of shorting its two terminals but not on the key, where usually it does nothing at all for 2-3 turns, then drives the solenoid in several times without turning the engine over and ultimately, sometimes after many attempts, the motor will engage and the engine starts.

Must be the key switch then? Replaced, makes no difference. Confirmed by shorting across the connections. No relay on the wire from switch to solenoid but adding one makes no difference. Baffling. Hope the OP's is somewhat less confusing.

 

[Stemar]

If the clicking isn't coming from the starter motor, could it be coming from a relay? If so, time to clean every connection in the circuits.

 

[RichardS]

I had to laugh ironically when I saw the thread title. My motorhome is currently at an auto-electrical shop where the highly recommended owner is scratching his head after a couple of days of testing. There is absolutely nothing wrong with the high current side, he has drop-tested everything, replaced the (faultless) earth connection, checked battery and cable connections (nothing wrong with them). The starter motor works perfectly using the old dodge of shorting its two terminals but not on the key, where usually it does nothing at all for 2-3 turns, then drives the solenoid in several times without turning the engine over and ultimately, sometimes after many attempts, the motor will engage and the engine starts.

Must be the key switch then? Replaced, makes no difference. Confirmed by shorting across the connections. No relay on the wire from switch to solenoid but adding one makes no difference. Baffling. Hope the OP's is somewhat less confusing.

It sounds to me like dodgy contacts inside the starter solenoid, assuming that it's a pre-engaged starter. The internal contacts are marginal and will work with direct shorting of the solenoid terminals but anything delivering slightly less current sometimes results in poor engagement.

Richard

 

[Boater Sam]

It sounds to me like dodgy contacts inside the starter solenoid, assuming that it's a pre-engaged starter. The internal contacts are marginal and will work with direct shorting of the solenoid terminals but anything delivering slightly less current sometimes results in poor engagement.

Richard

What many do not realise is that most solenoids have 2 windings, one initial pull-in that the start switch enables and the second hold in that the starter motor feeds when running.

 

[vyv_cox]

It sounds to me like dodgy contacts inside the starter solenoid, assuming that it's a pre-engaged starter. The internal contacts are marginal and will work with direct shorting of the solenoid terminals but anything delivering slightly less current sometimes results in poor engagement.

Richard

Our initial diagnosis was a duff starter motor, so we replaced it with new. Made absolutely no difference. Some very experienced brains have puzzled over this one but we heard this morning that a fault has been found. We shall see.

 

[rogerthebodger]

Our initial diagnosis was a duff starter motor, so we replaced it with new. Made absolutely no difference. Some very experienced brains have puzzled over this one but we heard this morning that a fault has been found. We shall see.

SWMBO ca has he same issue. It manifests itself when the car is hot the car been driven then left to heat soak.

She opens the bonnet and allows it to cool and it will then start.

Like you we replaced the starter motor and the solenoid does not click so it looks like the starter key/wiring connections that goes open circuit when hot so cnnot see the fault at home.

 

[TernVI]

If it starts when you short the big solenoid terminals, that tells you the motor is Ok, the high current wiring is OK, the battery is OK.
So try applying 12V to the solenoid's smaller contact.
If it starts reliably, then look at switches and wiring. There may be a relay, those solenoids can pull a fair current.
If it doesn't start, you have to look at whether the solenoid is stuck, open circuit, or whether the high current contacts are burned, dirty or not making contact for some other reason, or whether the solenoid is not moving far enough to engage.
If it chatters madly, then check the high current circuit of the solenoid, there is a secondary coil which helps hold the pinion engaged using the motor current, and throws the pinion out when the engine starts and the current reverses.

 

[ianc1200]

Many thanks to all for the ideas.