Canal Boat – July 2018

76 July 2018 Canal Boat canalboat.co.uk

Ask your questions [email protected] ASK THE EXPERTS

Q

It takes approximately 30

seconds of continually

turning to start my engine after

it has sat for 8 to 10 hours. Once

the engine starts there is quite a

vibration in the boat at idle

speed. When the rpm is raised to

1,000 revs the engine runs

smoothly up to 3000 revs, after

a few minutes it cuts out and

stops, after several turns it

starts and runs reasonably well

again. if the engine revs are kept

below 3000 the engine keeps

running. I have bled the fuel,

checked the injector spray

pattern and checked the valve

clearance all of that I found to be

okay. When the engine is under

load there is no excessive smoke

and all seems well then it just

stops. This engine was

purchased from a Yanmar

dealer as being fully

reconditioned and has only been

run for about 20 hours. The

dealer insists that it starts and

runs well. As the dealer is at the

opposite end of the country

from me I didn’t witness him

starting it.

SMITH ACKERGILL

A

TONY REPLIES: I assume

that you have checked any

filters and water traps to ensure

they have not been blocked by

dirty fuel or water including a

possible strainer that is often

under a cap on the lift pump.

I think that this is either an “air

in the fuel” or “lack of fuel”

problem. Much depends upon

whether Yanmar say that

engine is self-bleeding or not.

Does the exhaust smoke with

whitish smoke all the time you

are cranking? If it does you have

fuel present, so the lack of

starting is either not enough fuel

or lack of compression. If there is

little smoke present at first I

suspect that air has entered the

system and the engine is “self

bleeding” it out. If there is lots of

smoke virtually all the time you

probably have low compression

but in view of the history it might

just be that the engine is not yet

run in. However I think the dealer

needs a severe talking to.

Slacken the main injector pipe

unions on the injector end about

half a turn and spin the engine.

The pipes should drip AT ONCE. If

they do not then you have air in

the fuel.

With no history of the boat and

installation (like why it is having

a reconditioned engine fitted) it

is difficult to give advice at long

range. But check all pipe unions

between tank and engine for

tightness, including those on the

fuel pump, any filters/water

traps, and the injector pump.

Any union where the nut has

“run out of thread” requires

dismantling and a new olive

fitting.

Check the seals on all filters,

water traps and any lift pump

cap to ensure they are correctly

fitted, not damaged and are still

soft.

Also be aware that a good

installation may well have a

strainer gauze on the inner end

of the fuel pick up pipe. If this is

partially blocked it would create

excess suction in the supply

pipes and that can cause air to be

drawn in to the system. Likewise

make sure the fuel tank breather

is free from obstructions. Both

will cause fuel starvation.

Identify the fuel leak off pipe for

the injectors – this is the small

one. Follow it away from the

injectors and I expect it will run

the main engine filter. It might

stop there. This is fine as long as

the injector nozzles are not back

leaking gas from the combustion

chamber and providing the whole

fuel system is 100% airtight. If it

is not, air builds up in the top of

the filter and eventually gets

passed to the injector pump

where it stops the engine. Whilst

very small amounts of air are

going through the system the

engine will run roughly and

possibly misfire.

Delphi (was CAV) recommend

that the leak off pipe or another

pipe be extended back to the

top of the fuel tank from a high

point on the filter to pass fuel

(and any air) back to the tank

via a 0.5mm diameter

restriction. A suitable banjo bolt

may be available from your

local diesel specialist. I strongly

suspect that this modification

(unless it has already been

done) will cover up any air leak

and solve the problem.

Having said all of the above it

could be fuel starvation so if

you can suck plenty of fuel

from the tank via the filter inlet

pipe I would be suspicious of the

lift pump. They should supply

more than about half an

eggcup per stroke at about 3 to

6 psi.

Please come back with more

history and detailed symptoms

if you need more help.

Difficult to start

BACKCABIN

Q

According to the

temperature gauge, my

BMC 1.5 runs at around

60-70C (except when I towed

someone a couple of miles

last weekend and it went up

to 80C). A pal of mine who

used to have a BMC 1.5 told

me last night that 82C was

the normal operating

temperature, and we

surmised that the thermostat

may be stuck open?

I also intend to change the oil

filter myself, I’d be grateful if

you could recommend a

supplier of all such parts.

JULIAN NEWTON-TYERS

A

TONY REPLIES: Some

marinisers fit a lower

temperature thermostat to

their boats that use a calorifier

for hot water to stop

customers scalding

themselves quite as badly as if

an 82C thermostat were fitted.

Direct raw water cooled

boats boats also use lower

temperature thermostats.

You may be correct about

the thermostat and you could

change it if you want to as long

as it is not direct cooled.

However be aware that

someone may have tried to

cover up an undersized skin

tank problem or the like by

fitting a cooler thermostat.

If the temperature rises to

60 Cover about 10 minutes of

boating then the thermostat is

probably working as it should

but is a lower temperature

one. If it take ages to rise then

the thermostat. is probably

stuck open.

Regarding the oil filter, I

must refer you to the engine

mariniser because there is a

question over the type and

size of oil filter. But if you

know if its a “spin on” or

bowl type, I think ASAP

Supplies or Calcutt boats will

be able to help you.

Once you have the filter

part numbers any motor

factors should be able to

match them.

Cool running