Wren 44 TurboProp Users Manual. Copyright Wren Turbines Ltd February 2008 Page 36
Basic Servicing
Starter O-ring
There is little for you to do in the line of servicing so if the unit is
working - leave it alone. After some time however the starter
motor may start making screeching noises which indicates the
rubber O-ring in the clutch is worn.
The starter motor is held on the engine with three small grub
screws and after loosening these two turns the starter can be
withdrawn.
The O-ring can then be seen and picked out with a pin. A new one
can be ordered from Wren Turbines and popped in. The reverse
procedure is used to replace the motor but the clutch operating
length must be reset.
To set the operating length of the clutch, pull the black cap off the
motor, loosen the grub screws slightly and gently push the motor
all the way in. Then pull the motor back out about 1.5mm (1/16”)
and
gently
nip the grubscrews up. Do not tighten too much or the
magnets will crack with a sickening crunch and it might mean a
replacement starter.
A small drop of nail varnish on the screws will help ensure they
don’t vibrate loose. Don’t use a strong locking compound or they
will be impossible to remove later.
GlowPlug Replacement
It is presumed the operater is proficient at replacing the plug but a note on it’s preparation may
help. The plug must be replaced by one of the same type – the settings in the ECU on plug power
rely on this. If you replace it with one with aheavier element the ECU will surely blow it on the first
go as it will supply too high a voltage for it. If you go into the ECU settings and scroll through you
will find a “GlowPlug Power setting”. It is normally set to about 34. If your replacement plug is not
the same as before reduce the value by 10 and try it. It is easy to raise the value by 3 or 4 at a
time if it will not ignite.
A new plug will need its element teased out gently in order to expose the element to the propane
for satisfactory ignition. It is easily broken if overdone and if not done enough will not work well. If
you are not confident to do this you can order a pre-prepared glow plug from Wren Turbines.
The element should be teased until the coil is just nicely
visible.
Place your thumb nail over the area where the element wire is
welded to the body to help stop it from breaking as this is the
usual point.
Many glow plug elements are broken by nervous trembling
fingers bashing the element against the side of the plug-hole as it is being replaced into the
engine. If you are not sure you can do this carefully get someone else to do it for you.
