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Starting woes (help!)


Lochnevis

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For pretty much the first time, I've hit a problem where mining the forum for info from past threads hasn't provided the answer (or rather, it's provided several possible answers, and I've no idea where to start!)

So, here goes:

My boat's engine (Thornycroft 80 = Mitsubishi K4D, keel cooled) has always started pretty well, either in a couple of seconds in warm weather, or after 10-15 seconds cranking in the cold, but a few weeks ago it suddenly became much harder to start, usually need two or three attempts of ~ 30 seconds cranking.  But it was still starting, so I (stupidly...) put off solving the problem until I could get to a spot where I could moor up for a couple of weeks (I'm currently on the Thames, but was planning to move on to the canal in Oxford in a few days).  And then this morning it didn't.  So I'm currently a bit stuck, and in desperate need of the forum's collective wisdom (and hoping that Abingdon council are going to be understanding about me breaking their brand-new 3 day mooring limit!)

 

Some more info:

The engine turns over, but not fast enough.

Fuel is getting through (lots of vapour when I crank).  I changed the fuel filters just in case when the starting became more difficult, but it made no difference.

I don't have a clamp-meter, but I think the starter is drawing more current than it used to: I've had a 150A fuse on the starter battery for the last year, and it's always worked fine, but the first sign of the starting problem was the fuse blowing (and the replacement went straight away too, so I've removed the fuse block for now).

The starter battery is fairly elderly, and the alternator doesn't produce a great charging voltage (~12.7V, from memory).  My domestics charge from solar, but the starter charges only from the alternator.  The voltage on the battery after four attempts at starting this morning is 12.2V.  I've just hooked the starter up to the solar to give it a good charge.

The engine has been running fine once it started, and would restart pretty easily when warm (though still only after a couple of seconds cranking).

 

From reading everything I can find here and elsewhere, the possibilities seem to be (a) a starter motor problem, (b) a battery problem - but I don't see why this would have come on suddenly, (c) poor compression, (d) the injectors need servicing.  Is there anything I'm missing - and how should I go about working out where the problem lies?

 

Thanks everyone!

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If your starter battery is failing or just not fully charged, the engine will crank more slowly and the starter will draw MORE current than if it were full charged because it cannot get up to speed to generate any back EMF.

Starting with a flatish battery will destroy the starter and the battery eventually.

 

Having a fuse in the starter circuit is a bad idea, you have voltage drop across every connection and the thin fuse itself, remove it and make a good direct connection.

 

Jump your leisure battery bank onto your starter battery, + to +, the negatives will already be joined.

 

What state are your preheater plugs in?

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I'll give it a shot when I'm back at the boat.  I hadn't because I wasn't sure if doing so would knacker my domestics (which are Trojans in very good nick, so I was being ultra-cautious).  I assume that just doing this once or twice won't do them much/any harm, then?

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Using a weak battery places demand son the starter motor and alternator.

 

Since starter and alternators are not cheap a new battery would be a good investment .  You might first remove clean and refit the battery terminals . . and if you wish you could try charging the battery using a mains powered charger.  However sounds like you need a new battery.

The voltage from the alternator seems very low so see if it improves with a new battery and if not investigate further . eg \; Possible corroded electrical connections or defective wires

 

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4 hours ago, Lochnevis said:

I'll give it a shot when I'm back at the boat.  I hadn't because I wasn't sure if doing so would knacker my domestics (which are Trojans in very good nick, so I was being ultra-cautious).  I assume that just doing this once or twice won't do them much/any harm, then?

How do you charge your Trojans? I hope its higher that 13 volts

 

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1 minute ago, Mike the Boilerman said:

The 12.7 charging voltage could be being caused by a shorted cell on the starter battery. 

Or the same piss poor connection as causes the starting problem. If this were just a charging problem it would have shown up in the domestic battery long before any starting problem manifested itself.

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6 minutes ago, Sir Nibble said:

Or the same piss poor connection as causes the starting problem. If this were just a charging problem it would have shown up in the domestic battery long before any starting problem manifested itself.

 

Yes I see what you mean. Particularly as the op implies his trojans are getting properly charged. 

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Although it does sound very much like battery or cable connection problem there is incidentally on those engines usually, an electric fuel pump with a wee filter inside, under the end bayonet fitting end cap under which there is a spring holding the filter in, they are quite notorious for clogging up with muck and stopping engines.

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Diesels do need to crank quite fast to compress the air in the cylinder and get it nice and hot so the thing fires. Petrol engines in old cars with old batteries will start with slower cranking as there will be a spark to fire the mixture, that is a very broad generalisation and only a little bit of science in it. I reckon if you turn it over nice and fast your problems will vanish.

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2 minutes ago, Bee said:

Diesels do need to crank quite fast to compress the air in the cylinder and get it nice and hot so the thing fires. Petrol engines in old cars with old batteries will start with slower cranking as there will be a spark to fire the mixture, that is a very broad generalisation and only a little bit of science in it. I reckon if you turn it over nice and fast your problems will vanish.

I have been rebuilding a lot of starters for road sweepers. The slightest drop in performance results in insufficient rail pressure and no start. I was getting them back within weeks with brush leads and comm heat discoloured and spiral witness marks on the front of the roller clutch housing. I had the customer measure the distance from mounting flange to flywheel, 16mm. The distance from the starter flange to pinion teeth also 16mm. That's not right. I supplied a 3mm distance piece with each starter and I never see them now. This is only the second time in over 40 years I have overruled the designer of a machine, reasoning that if I believe the designer has made a mistake it is most likely that I just don't understand things as well as he does. In this case, someone clearly screwed up and I know that there is a huge heap of£600 starters at the factory because someone took their eye off the ball.

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So the engine was running fine when you stopped at the mooring? Presuming you sort the power issue I wonder if you may now have introduced another problem by changing the fuel filters, did you test for fuel before or after filter change?

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3 hours ago, ditchcrawler said:

How do you charge your Trojans? I hope its higher that 13 volts

 

 

2 hours ago, Sir Nibble said:

Or the same piss poor connection as causes the starting problem. If this were just a charging problem it would have shown up in the domestic battery long before any starting problem manifested itself.

 

2 hours ago, Mike the Boilerman said:

 

Yes I see what you mean. Particularly as the op implies his trojans are getting properly charged. 

The Trojans charge from an MPPT solar charger, and aren't connected to the alternator - I've got 500W of solar panels, so have never needed to connect them to the alternator charging circuit (or at least not often enough to have actually got around to it!).  

 

 

2 hours ago, bizzard said:

Although it does sound very much like battery or cable connection problem there is incidentally on those engines usually, an electric fuel pump with a wee filter inside, under the end bayonet fitting end cap under which there is a spring holding the filter in, they are quite notorious for clogging up with muck and stopping engines.

There is indeed - I changed it, too, though.  It's an awkward sod to change, as it's been mounted vertically, cap end down (do these things need to be a particular way up?!)

 

 

1 hour ago, Paringa said:

So the engine was running fine when you stopped at the mooring? Presuming you sort the power issue I wonder if you may now have introduced another problem by changing the fuel filters, did you test for fuel before or after filter change?

No, the problem started a few weeks ago, in that it was suddenly much harder to start the boat, but it was only today it completely refused.  The filters were changed when the problem started, and the engine has been running fine (once going).  So I hope it's just the one (probably battery) problem.

 

 

Thanks everyone for all of the help!  I'll try jump starting from the domestics in the morning, and assuming that does the trick, I'll go and get myself a new starter battery.  Then I suppose I'll start trying to troubleshoot the low charging voltage (assuming it is still low, rather than being caused by a problem with the battery)...

 

Edited by Lochnevis
to fix some dodgy formatting
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10 minutes ago, Lochnevis said:

The Trojans charge from an MPPT solar charger, and aren't connected to the alternator - I've got 500W of solar panels, so have never needed to connect them to the alternator charging circuit (or at least not often enough to have actually got around to it!). 

 

Oh now I'm REALLY curious! I too have 500W of solar and mine simply stops working for the three winter months. Are you saying yours works all through winter or have you not lived on board through a winter yet? Do you run an electric fridge through winter?

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13 minutes ago, Mike the Boilerman said:

 

Oh now I'm REALLY curious! I too have 500W of solar and mine simply stops working for the three winter months. Are you saying yours works all through winter or have you not lived on board through a winter yet? Do you run an electric fridge through winter?

I too had the same thoughts, and drew the same conclusions.

Phil 

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36 minutes ago, Mike the Boilerman said:

 

Oh now I'm REALLY curious! I too have 500W of solar and mine simply stops working for the three winter months. Are you saying yours works all through winter or have you not lived on board through a winter yet? Do you run an electric fridge through winter?

 

21 minutes ago, Phil Ambrose said:

I too had the same thoughts, and drew the same conclusions.

Phil 

I turn the fridge off when the solar can't keep up, usually around the end of October.  Other than that, LED lights, and all 12v (no inverter) - so pretty low power usage.

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58 minutes ago, Lochnevis said:

 

 

The Trojans charge from an MPPT solar charger, and aren't connected to the alternator - I've got 500W of solar panels, so have never needed to connect them to the alternator charging circuit (or at least not often enough to have actually got around to it!).  

 

 

There is indeed - I changed it, too, though.  It's an awkward sod to change, as it's been mounted vertically, cap end down (do these things need to be a particular way up?!)

 

 

No, the problem started a few weeks ago, in that it was suddenly much harder to start the boat, but it was only today it completely refused.  The filters were changed when the problem started, and the engine has been running fine (once going).  So I hope it's just the one (probably battery) problem.

 

 

Thanks everyone for all of the help!  I'll try jump starting from the domestics in the morning, and assuming that does the trick, I'll go and get myself a new starter battery.  Then I suppose I'll start trying to troubleshoot the low charging voltage (assuming it is still low, rather than being caused by a problem with the battery)...

 

They are normally mounted vertically with the filter cap underneath.

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12 hours ago, ditchcrawler said:

What sort of voltage do they cycle between

 

12 hours ago, Dr Bob said:

How are you (the op) monitoring your power? Volts, Amps in/out, SoC?

The starter battery isn't monitored (except when it stops working and I stick a multimeter on it!).  The domestics (2* T105 Trojans) are on a Smartgauge.

According to the Smartgauge, the batteries generally cycle between around 70 and 100%.  From November-January, they start to drop below 70%, and generally at around 60% I start to panic, and stop using anything apart from pumps and lights.  I may well spend more time in the pub in winter...  I don't think they've ever shown below 50%.  As for voltage, I can't remember what the lower end is, but they are usually around 12.9-12.95V fully charged under light load (just after dark at the end of a sunny day, with a few LED lights on, in other words).

Mind you, I might have jinxed myself saying they were in good condition - I just checked the water, and they were very, very low indeed.  Which is odd, because in the last 4 years, they've needed only very occasional and slight topping up.  I don't think it's longer than usual since they were checked, but maybe I've got a bit careless with them.  Or maybe something else has changed (I do have a new fridge, but the batteries didn't seem to be discharging quicker, so I don't think it's drawing anything crazy.

 

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Update: I went and bought a new starter battery this morning (same size as before, a 644).  The starter battery was definitely knackered, but it seems that there's an underlying problem.  I'm now back to where I was a couple of weeks ago - it takes several attempts to start: four times cranking ~30 seconds.  After a while (on the 4th attempt, for most of the time) the engine sounds like it's about to fire, but keeps not quite managing it.  I couldn't swear that the starter is turning over as fast as it used to, but it doesn't sound unusually slow or otherwise wrong (and it's turning over much faster than it was yesterday, with the old battery).

 

It looks like there is definitely something up with either the alternator or some related piece of wiring, as the charging voltage from the alternator was still very low (12.6V, not the 12.7V I said above).  Unfortunately I didn't have time to move the boat today (so I've left the starter hooked up to the solar charger+domestics to make sure it gets a proper recharge.

 

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