Rebuilding the Rotax 447 ultralight aircraft
engines.
This manual has been
prepared as a guide to help service and repair the 447, 447, and
503 Rotax air cooled ultralight engines. It is primarily published
to be used with the "Rebuilding the Rotax ultralight engine
video," produced by Dave Loveman. Some of the terms used in the
manual and in the video may not match those used in parts manuals
available for these engines. All pictures, diagrams, drawings or
graphs, used are for the general identification only, and are not
to be taken to represent technical drawings or replicas of exact
parts.
When rebuilding a Bombardier Rotax ultralight engine is
strongly recommended that the rebuilder use only original
manufacturers replacement parts.
WARNING !
This information relates to the service and repair of
Bombardier Rotax ultralight engines, and has been used safely and
effectively. However I Disclaim liability for any and all damages
and or injuries resulting from the improper use of the contents.
It is strongly recommended that any service to be carried out be
verified by a highly skilled, knowledgeable ultralight engine
mechanic.
Introduction
This manual covers the following Bombardier Rotax ultralight
engines.
Type Rotax 447 fan cooled ultralight
Type Rotax 447 fan cooled ultralight
Type Rotax 503 fan cooled ultralight
To verify engine type consult serial number plate located on
fan shroud housing.
Engine lower shroud removal
Tools required
Racket
13 mm socket
10 mm socket
6 mm allen wrench
plastic or rubber mallet
Rotax engine lower engine shroud
removal
To remove the bottom shroud (2 on the 503) using the () mm
allen wrench remove 4 bolts retaining the exhaust manifold. With
the 13 mm socket remove the 4 bolts holding the intake manifold.
With the 10 mm socket remove the self tapping screw from the PTO
side cylinder cowling on the 503. With the rubber mallet gently
tap intake manifold to break it free if necessary. With the
manifolds off remove the lower shroud(s).
CAUTION !
It may be necessary to GENTLY TAP the intake manifold with a
rubber mallet to free it from the intake manifold gaskets, as the
tend to stick to the lower cowling.
Inspection:
Inspect the intake manifold for cracking at the retaining bolt
holes, and for leakage at the gasket, or sealing ring between the
two intake manifold halves.
Inspect rubber intake socket for signs of UV deterioration.
Rotax fan tower removal
Tools required
() mm allen wrench
() mm socket
ratchet
Locate the 4 ()mm head allen bolts retaining the fan tower to
the crankcase halves. Remove them and the fan tower will come
free. At this time it is suggested the two ignition wires running
to the coils, blue on red/blue on black, the ignition suppressor
box wires and the engine ground wire (brown) be disconnected. To
do this remove the three ()mm self threading bolts holding the
lower coil to the fan tower. This will allow disconnection of the
ground wires. The fan tower can now be removed completely from the
engine.
Inspection:
Inspect the fan tower in the area where the four allen bolts
retain it to the crankcase halves for cracking.
Inspect the fan tower in the area where the fan supports attach to
the fan tower.
Inspect the fan for cracks or sign or damage.
CAUTION!
ENGINE IS EXTREMELY HEAVY AND AWKWARD. DO
NOT ATTEMPT TO REMOVE FROM AIRCRAFT WITHOUT ADEQUATE HELP!
Rotax engine top shroud removal
Tools required
Ratchet
13 mm socket
flat screw driver
10 mm socket (for 503)
Plastic or rubber mallet
To remove the engine top shroud, remove the three 13 mm socket
head bolts located on the top of the engine cowling. (4 bolts on
503) Loosen the 6 (8 on the 503) slotted screws located at the
seam of the upper and lower shroud halves. The top shroud should
now lift off.
Inspection:
Inspect the top shroud for cracking, missing pieces.
Rotax fan cover removal
Tools required
Flat screw driver
To remove the fan cover, carefully pluck the three retaining
clips from the holes holding them into the fan tower. Then gently
pull outward on the cover, until it is off.
Rotax aircraft engine rebuilding manual for the
447, 447, and 503 aircraft engines.
Recoil removal
Tools required
extension ratchet
10 mm socket
To remove the recoil from the engine remove the 4, 10 mm socket head bolts that retain
it to the fan tower. Disconnect suppressor box, remove recoil.
Inspection:
Inspect the recoil housing for cracking around the center, and where the recoil rope
exits the housing.
Inspect the recoil rope for fraying.
Starter Pulley/Fan Pulley and Fan Belt Removal
Tools required
( ) allen wrench
locking pin
plastic mallet
Located behind the recoil starter assembly is the starter pulley and fan pulley. To
remove these lock the crankshaft, by placing the locking pin part # (), into the fuel pump
impulse hole. The slowing turn the engine over until it locks. With the crankshaft locked
use the () allen wrench to remove the 3 ()mm bolts. This allows the removal of the recoil
cup and pulley. It may be necessary to gently tap the fan pulley with a plastic or rubber
mallet.
Caution !
Note the direction of travel of the fan belt prior to removal by
locating the writing on the belt and noting the direction.
Once the cup and pulley have been removed rotate the fan belt in the fan blades until
it is off.
Inspection:
Inspect the starter pulley cup for signs of wear or damage.
Inspect the fan pulley for signs of wear or damage.
CAUTION!
This is a special locking pin developed for this purpose. The use
of any other tool, or material may cause serious damage to your engine.
CAUTION !
During removal of the magneto, the key used to align the magneto
to the crankshaft may come loose, and can be easily lost. When pulling the magneto free be
careful not to loose the key, or that it does not get pulled into the magneto.
Caution !
Make sure that the puller bolts are the correct length. The use
of incorrect bolts can strip the magneto threads and/or damage the internal coils.
Marking the stator plate
Tools required
Hammer
Chisel
To aid in reassembly it is suggested that the stator plate and crankcase be marked at
this time. To do this take a chisel, and hammer and imprint the stator unit and crankcase
half with an alignment mark.
Stator plate removal
Tools required
() mm allen wrench
Remove the two () mm allen screws, washers, and lock washers holding the stator plate
to the crankcase halves. The stator unit will now come free. Slowly pull the stator plate
out while pulling the wiring harness through the crankcase hole. Once the wires are free
the stator unit can be completely removed from the engine.
Inspection:
Inspect the stator unit for signs of wear or damage.
Inspect the points and condensers for signs of oil contamination.
Inspect the coils for damage.
Inspect the wiring for wear, cuts, or pinching.
Caution !
Be careful not to cut or bare the wires on the sharp edges while
pulling them through the crankcase hole.Removing the cylinders
Tools required
Rubber mallet
Removing the cylinders
With the cylinder heads removed the cylinders can be GENTLY
lifted off. It may be necessary to tap the cylinders gently with a rubber mallet to break
the cylinder base gasket free.
Inspection:
Inspect the interior of the cylinder for signs of wear or damage.
Inspect the interior of the cylinder for signs of seizure.
Inspect the interior of the cylinder for signs of aluminum deposits.
Inspect the cylinder with your finger about 5/8s of an inch from the top for signs of
wear.
CAUTION !
During cylinder removal ensure that the pistons and connecting
rods do not bang against the side of the crankcase halves or head studs. Be EXTREMELY careful
that damage is not done to the piston/ skirts during removal of the second cylinder.
Removing the wrist pin clips
Tools required
Ice pick or other sharp pointed tool
Rag or paper towel
Eye protection
For disassembly it is only necessary to remove two wrist pin clips. These are the clips
on the PTO side and Magneto side of the pistons. While wearing eye protection, carefully
insert the point of your tool into the groove on the side of the wrist pin hole, until it
is under the wrist pin clip. Using a rag or a towel with your other hand cover the clip
area. Now slowly apply pressure and pry the clip out.
CAUTION:
The wrist pin clip is very springy, use a rag or other material
to prevent it from flying free. Wear eye protection. Clear work area of bystanders.
Wrist pin removal:
Tools required
Wrist pin puller/socket/screw driver
small hammer
To remove the wrist pin raise the magneto piston to TDC. Insert the wrist pin puller
through the pin, lock the puller clip tighten up the puller to extract the pin.
To remove the wrist pin with a screw driver or socket, use a socket or screw driver
that is a slight smaller diameter than the pin. Come in from the side of the pin that
still has the wrist pin clip in it, Gently tap the top of the socket until the pin is
free.
Once the pin is free remove the piston. To prevent damage to the piston never place the
piston on its skirt, always lay it on its dome.
Repeat the procedure for the piston on the PTO side.
Rebuilding the Rotax 447, 447, and 503
ultralight aircraft engines.
Inspection
Inspect the dome of the piston for signs of damage.
Inspect the dome for signs of carbon build up, and ignition
burning pattern.
Inspect the rings for signs of damage.
Inspect the piston sides for signs of seizure.
Inspect the rings for signs of seizure and carbon buildup.
Inspect the ring dowels for signs of damage or wear.
Inspect the ring lands for signs of damage/wear/carbon build up.
Inspect the wrist pin clip retaining groove for signs of wear
damage.
Inspect the piston sides for signs of wear or damage.
Inspect the base of the skirts for shine, indicating piston
slop.
Inspect the underside of the piston dome for carbon build up.
Inspect the wrist pin bearing for signs of wear or
contamination.
Inspect the wrist pin for signs of bluing ( an indication of
heat), wear, or damage.
CAUTION:
Always lay the piston on its dome!
Support and protect the piston and connecting rod assembly to
prevent accidental damage.
WARNING: If your engine is equipped
with cageless wrist pin bearings these bearings will fall out
once the wrist pin is removed. Take whatever steps necessary to
prevent their loss Separating crankcase halves.
Tools required
Ratchet
10 mm socket
13 mm socket
() mm allen wrench
Screw driver
Rubber mallet
Separating the crankcase halves
To separate the crankcase halves, turn the remaining engine
assembly upside down, so that it is sitting on the cylinder head
studs. Remove the 4, 10 mm head bolts (on the 447/447) from the
outside of the cases. Remove the remaining 13 mm head bolts,
from the casing, starting from the one end and working to the
other.
On the 503 some of these 13 mm bolts at the PTO end of the
casing have been changed to allen head bolts to allow for socket
installation.
On the 503 the 4 outside bolts are 13 mm head rather than 10
mm.
With all of the bolts removed, insert a screw driver into the
non sealing area between the crankcase halves and pry up gently
in several places on both sides of the casing.
Then using a rubber mallet gently tap the crankshaft at
either end to break it free from the casings. The bottom
crankcase should now come free. After the bottom case has been
removed, remove the crankshaft, by placing your hands around the
crank at either end and using your thumbs pry down on the casing
while lifting up on the crank until it comes free.
Inspection:
Inspect the crankcase bolts for signs of corrosion.
Inspect the seals for signs of leakage.
Inspect the crankcase halves for signs of damage.
Inspect the crankcase halves for sings of wear in the bearing
retaining areas.
Inspect the crankshaft bearings for signs of wear.
Inspect the connecting rods for signs of wear or bluing.
Inspect the center crank spacer for signs of seizure.
Inspect the crankshaft key way for signs of wear.
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