Service Manual
31AS2B5 Snow Thrower
IMAGE SHOWS YARD-MAN UNIT
NOTE: These materials are for use by trained technicians who are experienced in the service and repair of outdoor power
equipment of the kind described in this publication, and are not intended for use by untrained or inexperienced individuals.
These materials are intended to provide supplemental information to assist the trained technician. Untrained or inexperienced
individuals should seek the assistance of an experienced and trained professional. Read, understand, and follow all instructions
and common sense when working on power equipment. This includes the contents of the product s Operators Manual, supplied
with the equipment. No liability can be accepted for any inaccuracies or omission in this publication, although care has been
taken to make it as complete and accurate as possible at the time of publication. However, due to the variety of outdoor power
equipment and continuing product changes that occur over time, updates will be made to these instructions from time to time.
Therefore, it may be necessary to obtain the latest materials before servicing or repairing a product. The company reserves the
right to make changes at any time to this publication without prior notice and without incurring an obligation to make such
changes to previously published versions. Instructions, photographs and illustrations used in this publication are for reference
use only and may not depict actual model and component parts. Copyright 2005 MTD Products Inc. All Rights Reserved
MTD Products LLC - Product Training and Education Department
FORM NUMBER 769-01416
9/2004
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31AS2B5-711 Snow Thrower
31AS2B5-711
1.
CONTROLS
The auger control bail and the pull start handle are
mounted on the main handle for easy accessibility. The
pull rope and mitten-grip handle is secured to the right
handle with a bracket to keep the cord away from other
items and allow for direct and easy in line pull. See Fig-
Yard-Man Version
Control Bail
Pull Start
Snow Thrower Model Number #31AS2B5- 711 Serial
Number 1E074B20005
NOTE: The equipment that was used to write
this section was a prototype and was without
labels. There may be subtle differences between
prototypes and production equipment but the
disassembly procedures preformed will remain
the same.
Figure 1
2.
AUGER
The auger assembly is also easily accessible for main-
tenance and periodical replacement of the rubber flails
on the auger assemblies. See Figure 2.
GENERAL INFORMATION
Tecumseh Engine HSSK 50 designated as a (C)
engine with 125 hours life expectancy. Oil recommen-
dation is 5W30 - Sump capacity is 21 ounces
Rubber Flails
This is a four-cycle, horizontal crankshaft, air-cooled
engine equipped with a 120 V A.C. operated electric
starter.
NOTE: Refer to the engine manual for start and
stop and maintenance procedures.
Figure 2
3.
A/C STARTER
From the rear there is easy access to the start/stop
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switch and the A.C. plug connector with starter button
that is used for the electric start. See Figure 3.
5.
MUFFLER
View showing the muffler and pipe at top left. See Fig-
Key Switch
Muffler Tailpipe
110 A/C Plug
Float Bowl Drain
Figure 3
Figure 5
4.
BACK OF UNIT
The Model tag is located on the back of the unit and
includes phone numbers for customer assistance:
Troy- Bilt 330-558-5520 or 1-800-520-5520. The choke
control is shown on the right side of the carburetor
NOTE: Unit is tipped up on the auger housing to
view carburetor and the carburetor bowl drain for
removal of bad gas or water from the bowl/float
area.
6.
SHAVE PLATE
The adjustable shave plate can be turned around when
worn on one side. See Figure 6.
Choke Control
Model Plate
Reversable Shave Plate
Gas Tank
Figure 4
Figure 6
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7.
DISCHARGE CHUTE
8.3. Inspect the idler bracket tension and return
springs and note location of connections. See
The mitten grip handle on the snow chute allows easy
adjustment side to side. See Figure 7.
Return Spring
Tension Spring
Figure 9
Figure 7
8.4. Using a 7/16" socket and a 7/16” box wrench,
remove the bolt securing the idler to the idler
arm. Inspect the idler bearing for freedom of
movement. Upon replacement note the position
of the larger retaining washer that has the top
position cut flat to clear the belt cover. See Fig-
8.
AUGER DRIVE BELT REPLACEMENT
8.1. Remove the five (5) screws on the perimeter of
the belt cover using a 3/8" socket with short
extension and ratchet. See Figure 8.
Belt Retaining Washer
Perimeter Screws
Figure 8
Figure 10
8.2. With the cover removed inspect for wear on the
belt and movement of the idler bracket. See Fig-
8.5. Push down on the idler bracket to lift the belt
brake shoe away from the belt. The belt can then
be lifted out of the auger pulley and off the
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engine pulley. Replace by using the same proce-
Pull down on idler arm
Brake Shoe
Figure 13
Figure 11
AUGER REMOVAL
9.3. Using a 3/8” socket, remove the three retaining
screws securing the bearing retainer housing to
the auger housing. See Figure 14.
9.
9.1. Place a two by four wedge in the housing to hold
the auger from turning. Using 1” socket, remove
the auger pulley nut. The shaft is reverse
threaded and the nut is removed by turning it
clockwise. See Figure 12.
Bearing Retainer Housing
2x4 Wedge
Figure 14
Figure 12
NOTE: During reassembly place the 2X4 at the
base of the housing center and tighten in the
opposite direction.
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9.4. Remove and inspect the bearing and heavy
washer for ear or damage. See Figure 15.
9.6. Inspect the auger assembly for wear on the rub-
ber flails. Check the shaft for straitness. Check
the welds for cracks or breaks. See Figure 17.
Bearing and Washer
Figure 15
Figure 17
9.5. Facing the housing, slide the auger assembly to
the right, and then remove the auger and shaft
assembly from the housing. See Figure 16.
10. SPARK PLUG ACCESS
Access to the spark-plug is through an access hole on
top of the main housing next to the oil fill tube. See Fig-
Slide auger assembly to the right
Access Hole
Spark Plug
Figure 16
Figure 18
5
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11.
FRONT SHROUD COVER REMOVAL
handle out of the chute assembly. See Figure
11.1. Remove the three screws from the inside top of
the auger housing using a 3/8" socket and
Directional Deflector
Cover Screws
Front Tab
Upper Retaining Ring Tab
Figure 21
11.4. Remove the directional deflector from the chute
assembly and you will be able to lift the shroud
over the lower chute. See Figure 21.
Figure 19
11.2. Remove the remaining five ( 5 ) perimeter
screws and two ( 2 ) screws holding the starter
plug assembly using a 5/16" socket. The shroud
is slotted to allow the removal from around the
starter cord. See Figure 20.
NOTE: This picture also shows releasing the tab
on the chute-retaining ring using a long blade
screwdriver. This would be necessary to remove
the chute retaining ring.
11.5. Removing the chute-retaining ring requires
releasing a lower tab from under the housing.
Lower Retaining Ring Tab
Figure 20
11.3. Remove the handle from the directional chute by
releasing the front tabs on the handle assembly
from the front opening of the chute and slide the
Figure 22
NOTE: This is somewhat difficult. If the lower
chute is not being replaced, it makes reassem-
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bling easier to leave the lower chute attached
and remove the deflector. See Figure 23.
The lock ring can now be inspected. Become familiar
with how it latches and holds the chute assembly
securely to the main housing. You must properly fit the
spring detent that holds the chute in a position. See
Figure 23
11.6. Remove the gas cap and the oil dipstick and
then lift off the shroud.
Figure 25
With the Shroud removed you now have complete
access to the engine, starter, fuel tank and all related
items for servicing or replacement. See Figure 24.
Chute components. See Figure 26.
Figure 26
Figure 24
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12.2. Using a 1/2” socket, remove the four bolts and
spacers attaching the engine to the left side of
NOTE: During reassembly, align the chute
assembly by facing it towards the plastic retain-
ing ring. Be sure the chute is positioned all the
way to the right or left upon re-assembly. See
Retaining Ring
Engine Mounting Bolts (4)
Figure 29
12.3. Using a 1/2” socket, Remove the two bolts
securing the lower base of the engine to the sup-
port bracket welded to the wheel axle.
Figure 27
Check that the upper and lower flanges lock into the
retaining ring and that the latch closes and locks prop-
erly. See Figure 28.
Lower Engine Mounting Bolts
Figure 28
12. ENGINE REMOVAL
12.1. Remove the discharge chute and engine cowl-
ing.
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13. GAS TANK
13.1. A wire retainer holds the gas tank. The tank can
easily be replaced by pushing the wire out of the
lower support plate at the bend on the side of the
Press DOWN here
Figure 30
NOTE: The gas line clamp is accessible below
the mounting bracket.
Clamp
Gas Line
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