Issue 4
April2012
Section 4
Engines and Propulsion Systems
Original Arrangements
Both boats were originally offered with a fitted outboard bracket as
standard, with a choice of petrol or diesel saildrive engines as optional
extras. Engines from Vire, Petter and Volvo were offered, mostly
about 7.5hp. Many of these of these original engines have survived,
despite their age, but many have been replaced by more powerful
units. If a purchaser opted for an inboard engine, a small fuel tank of
about 20 litres capacity was fitted in the lazarette, with the filler
situated in the top of the transom coaming.
The vast majority of boats now have inboard diesel engines, a few of
these being shaft driven, and the information below essentially relates
to these inboard diesels. The picture shows a newly-installed Volvo
D1-13
Overheating
This is probably one of the most frequent problems that arises, frequently signalled by the
overheat alarm sounding, or steam issuing from the exhaust. The causes are many and varied,
but two of the more obvious, and easy ones to check, are a blocked water inlet eg by a plastic
bag, or an impeller failure; Yanmar engines suffered particularly from the latter. A quick look at
the exhaust outlet will tell if cooling water is being ejected or not. Other causes are more difficult
to diagnose and cure, as will be seen in the items below. Mismatch between engine and propeller
is one of the less obvious reasons; some indication of this is given if the exhaust smoke is black
when the engine is more or less flat out.
Engine Failure
One of the more worrying problems. The most usual reason for this is either a blocked fuel line or
air in the fuel line. Guidance on bleeding air from the system can be found in the Reference
Library items below. A suspected blockage in the system – or, rarely, a failed pump – can be
checked by loosening the fuel feed at the injector(s) and cranking the engine with the throttle
wide open. If there is no seepage of fuel - a piece of kitchen towel is an excellent tell-tale - then
there is a blockage. Working back through the pipework, loosening one joint at a time and
cranking the engine, should enable the blocked section to be identified and removed for cleaning
out. And then bleeding the system.
Starting Difficulties
There is a host of reasons why an engine my be sluggish to start, including a faulty injector, poor
compression due eg to stuck piston rings, and air in the system. A low battery can also be the
culprit because it turns the engine over too slowly. If the engine hasn't fired up within about 20
secs of total cranking time, then the cooling water inlet valve should be closed until the engine is
running. Failure to do this results in a build up of cooling water in the exhaust system which could
find its way into a cylinder, with expensive results.
Sometimes, a reluctant engine can be persuaded to start with a shot of a 'quick start' spray into
the air intake, but the use of this should be avoided, if possible, because there is apparently a
real risk of serious damage to the engine. An alternative – not always practicable – is to warm the
air intake, eg with a hair drier!
Fuel
All fuel, particularly diesel, should be filtered as it is poured into the tank. A funnel with an
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