Tuesday, 10 November 2015

Engine won't start

This is one in a series of A Guide to Narrow Boat Problems.

Problem
Engine won't start 
Causes
Several possible causes.
A Engine makes no attempt to turn over – may be faulty starter motor solenoid, starter motor or no electrical supply to the solenoid. The latter can be checked with a multimeter. If a click is heard from the starter motor, but it doesn’t engage with the flywheel, it may be a faulty gear mechanism, similarly if the starter motor can be heard rotating but the engine doesn’t turn over. If the batteries are completely flat, it will show up on the battery condition monitor.
B Engine turns over slowly but won’t fire – probably low battery (confirm with battery condition monitor). Could be general damp or a faulty alternator. Possibly discharged battery.
C Engine turns over at normal speed but won’t fire – could be that glow plugs not energised for long enough or a failure of one or more of the glow plugs or their power supply (this can be checked with a multimeter).
Could also be a fuel problem (no fuel, blocked filter, air lock in fuel system) as in this blog entry.  Generally speaking, if a diesel engine has a correctly timed fuel supply to the injectors and it’s heated by either the glow plugs or residual heat in the cylinders, it will fire.
Solutions
First allow at least ten seconds for diesel plugs to heat up before starting, in neutral, with high revs. For an obviously damp engine use a dry cloth over any damp surfaces then spray area with WD-40. The recurring problem is more likely to be caused by alternator, faulty leads, plugs etc which may need replacing.
Once started make sure battery gets a full charge, leaving it to run, in gear and under load, until the battery condition monitor shows a full charge. 
Check battery charge levels with multimeter. Clip your meter across the battery terminals and take an immediate reading. If more than 12 volts battery is probably OK but if less, battery may be undercharged.
If domestic batteries are discharged but starter battery is OK switch to starter and start engine. Then switch to "charge both" with engine running until batteries recover. If they do not recharge and hold their charge, replace asap.
If all batteries are discharged try to get a start from another boat by connecting their battery to yours with heavy duty jump start leads. If mains supply is available use a mains battery starter.
Avoidance
Install permanent battery level indicator and check regularly. Always switch between starter battery and domestic batteries, charging both together but using starter battery only for starting the engine. Keep engine compartment dry and well vented. Clear drains. Clear bilges with pump and finally sponge and cloth to limit condensation in the engine compartment. Start from time to time throughout the "off" season and leave under load in gear for a while to recharge batteries.

Standard ammeter showing charge slowly moving back to zero
See also blog entry on Battery Condition Monitor.
 

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