MTD 380 User manual

Service Manual
MTD Products LLC - Product Training and Education Department
FORM NUMBER 769-01419
9/2004
Model 380 Two-Stage Snow Thrower
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

Skid Shoe Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Skid Shoe Removal and Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Shave Plate Removal and Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Belt Removal and Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Auger Shear Bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Auger Cable Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Wheel Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Drive Axle Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Transmission Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Auger Pulley Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Auger and Impeller Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Spiral Assembly Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Impeller Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Reducer Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Reduction Transmission Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Auger Cable Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Directional Discharge Chute Assembly Removal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Removal of the Auger Idler Bracket . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Engine Pulleys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Carburetor Bowl Drain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Table of Contents
TOPIC PAGE

Model 380 Two Stage Snow Thrower
1
MODEL 380 TWO STAGE SNOW THROWER
31A-380D000 Serial number 1F-193I40012.
Please refer to the owners manual for Assembly
Instructions, Preparation, Operation, Maintenance,
S t o r a g e a n d S a f e t y p r e c a u t i o n s .
NOTE: These materials are prepared for use by
trained technicians who are experienced in the
service and repair of this type of equipment
described in this publication, and are not
intended for use by untrained or inexperienced
individuals. All such individuals should seek the
assistance of an authorized service dealer.
Proper set up is very important to the long life and
problem free operation of power equipment.
WARNING: Before servicing, repairing, or
inspecting, disengage all clutch levers and stop
engine. Wait until all moving parts have come to
a complete stop. Disconnect spark plug wire and
ground it against the engine to prevent unin-
tended starting.
NOTE: Some procedures require you to tip the
snow thrower up on the front of the auger hous-
ing. If there is fuel in the gas tank, place a piece
of plastic wrap over the gas tank opening and
screw the cap back on the tank tightly. This
should keep gas from leaking fromthe cap vent.
NOTE: a piece of plastic wrap or the parts bag
can be used to seal the cap from possible gas
leakage.
1. SKID SHOE ADJUSTMENT
To prevent excessive and uneven wear on the Shave
Plate at the bottom of the snow thrower auger housing,
it is necessary to properly adjust the Skid Shoes.
Disconnect Spark
Plug Wire
Plastic Wrap
Service Manual
Model 380 Two Stage Snow Thrower

Model 380 Two Stage Snow Thrower
2
1.1. Place a piece of carton cardboard under the
shave plate. See Figure 1.1.
1.2. Loosen the two carriage bolts which secure each
skid shoe to the auger housing. Lower the skid
shoes to the ground and retighten the carriage
bolts.
2. SKID SHOE REMOVAL AND REPLACEMENT
2.1. Remove the two carriage bolts, bell washers and
hex nuts securing the skid shoes to the auger
housing. See Figure 1.1.
2.2. Reassemble new skid shoes with the hardware
just removed. Make sure the cupped side of the
washer goes against the skid shoe and that the
skid shoes are adjusted as described in Section
1.
3. SHAVE PLATE REMOVAL AND INSTALLA-
TION
3.1. Remove both skid shoes and hardware including
carriage bolts, bell washers and hex nuts which
attach shave plate to the snow thrower housing.
See Figure 1.1.
3.2. Reassemble new shave plate, making sure
heads of the carriage bolts are to the inside of
the housing. reinstall skid shoes and tighten
securely.
4. BELT REMOVAL AND REPLACEMENT
NOTE: There are two belts on the unit, the auger
belt and the drive belt. It is recommended that
you replace both belts at the same time.
AUGER BELT
4.1. Using a 5/16” socket, remove the screw securing
the right side of the belt cover to the drive hous-
ing. See Figure 4.1.
4.2. Press in on the tabs on each side of the cover
and lift upwards pulling the belt cover out from
around the engine.
4.3. Slip the front auger belt off the engine pulley
pushing it down between the idler bracket and
the engine pulley. See Figure 4.3.
Figure 1.1
Cardboard
Shave Plate
Skid Shoe
Carriage Bolt, Bell Washer, Hex Nut
Figure 4.1
Screw
Belt Cover
Figure 4.3
Auger Belt
Drive Belt

Model 380 Two Stage Snow Thrower
3
4.4. Squeeze the auger control bail to release the
tension on the auger belt brake; remove the belt.
See Figure 4.4.
4.5. Replace with a new belt AFTER replacing the
drive belt.
DRIVE BELT
NOTE: Replace the drive belt before reassem-
bling the new auger belt.
4.6. Tip the snow thrower up and forward so that is
rests on the auger housing.
4.7. Remove the spring that connects the transmis-
sion to a bolt on the right hand side of the engine
frame. See Figure 4.7.
Figure 4.4
Auger Idler
Auger Belt Brake
Figure 4.7
Extension Spring
Recoil rope eases removal
Transmission
4.8. Pivot the transmission forward to release pres-
sure on the drive belt and remove the belt from
around the engine pulley and transmission.
4.9. Replace both belts in reverse order of disassem-
bly.
5. AUGER SHEAR BOLTS
5.1. The augers are secured to the spiral shaft with
two shear bolts and hex lock nuts. If you hit a for-
eign object or ice jam, the snow thrower is
designed so that the bolts may shear. If the
augers do not turn, check if the bolts have
sheared. Two replacement shear bolts and hex
lock nuts have been provided with the snow
thrower.
NOTE: NEVER replace the auger shear bolts
with standard hex bolts. Any damage to the
auger gearbox or other components, as a result
of doing so, will NOT be covered by your snow
thrower warranty.
6. AUGER CABLE ADJUSTMENT
Periodic adjustment to the auger control cable may be
required due to normal stretch and wear on the auger
belt. Adjustment is needed if the augers seem to
hesitate while turning, but the engine maintains speed.
6.1. Remove the screw securing the belt cover to the
right side of the housing. See Figure 6.1.
6.2. Press the tabs that secure it to the snow thrower
housing. Remove the belt cover and set it aside.
6.3. You can now access the auger cable. Adjust the
two hex nuts on the auger cable towards the
Figure 6.1
Screw
Belt Cover

Model 380 Two Stage Snow Thrower
4
spring to increase the tension on the auger belt
when it is engaged. See Figure 6.3.
6.4. Reassemble the belt cover.
7. WHEEL REMOVAL
7.1.Tip the snow thrower up and forward so thatit
rests on the auger housing. See Figure 7.1.
7.2. Using a 1/2” socket and ratchet, remove the lock
bolt and bell washer securing the wheel to the
axle.
7.3. Remove the wheel from the axle.
NOTE: The wheel hubs are made from a special
polymer. They will not rust or corrode.
8. DRIVE AXLE REMOVAL
8.1. Remove the wheels as described in section 7.
8.2. Remove the cotter pin and clevis pin securing
the 70T gear to the axle shaft. See Figure 8.2.
8.3. Slide the axle from the drive housing as you
remove the gear from the axle shaft.
8.4. Remove the hex flange bearings from the drive
housing.
9. TRANSMISSION REMOVAL
9.1. Tip the unit up and forward on the auger hous-
ing.
9.2. Remove the wheels as described in section 7.
Figure 6.3
Auger Cable
Adjustment Hex Screws
Idler Arm
Figure 7.1
Lock Bolt and Bell Washer
Figure 8.2
Cotter Pin an Clevis Pin
70T Gear
Axle Shaft
Drive Axle Components
Hex Flange Bearings
70T Gear
Axle Shaft Cotter Pin Clevis Pin

Model 380 Two Stage Snow Thrower
5
9.3. Remove the tension spring attached to the frame
and transmission. See Figure 9.3.
9.4. Remove the belt from around the transmission
pulley.
9.5. Tip the transmission forward. Using a pair of
needle nose pliers, squeeze the tabs on the
drive cable where it attaches to the transmission
and remove the cable from the bracket. See Fig-
ure 9.5.
9.6. Remove the drive cable Z fitting from the trans-
mission housing.
Figure 9.3
Extension Spring
Transmission
Transmission Pulley
Figure 9.5
Drive Cable Tabs
Drive Cable Spring
Pliers
9.7. Remove the cotter pins and flat washers secur-
ing the transmission mounting axle to the drive
housing. See Figure 9.7.
9.8. Move the transmission to the left and to the right
and pivot it from the drive housing.
9.9. Remove the two hex flange bearings from the
drive housing.
NOTE: The transmission is not serviceable. The
transmission must be returned to the factory
unopened for warranty reimbursement.
NOTE: The pinion gear and roll pin are service-
able.
10. AUGER PULLEY REMOVAL
NOTE: In order to ease removal of the auger
pulley it is recommended that you remove the
transmission first. See transmission removal
section for instructions.
Figure 9.7
Cotter Pins and Flat Washers

Model 380 Two Stage Snow Thrower
6
10.1. Using a ½” socket and ratchet, remove the lock
bolt securing the auger pulley to the auger gear-
box drive shaft. See Figure 10.1.
NOTE: Use a drive belt to apply pressure to the
auger pulley and hold in place during removal of
the lock bolt.
10.2. Inspect the idler arm, flat idler pulley, tension
spring and cable for proper operation. Lubricate
between the idler arm and auger housing at any
point of contact. See Figure 10.2.
11. AUGER AND IMPELLER REMOVAL
11.1. Remove the wheels to ease removal of the
transmission. See section 7.
11.2. Remove the Transmission. Refer to Section 9.
11.3. Remove the Auger Pulley. Refer to Section 10.
11.4. Using a 1/2” socket, remove the three hex nuts
and lock washers securing the bearing housing
to the auger housing. Set the bearing housing
aside. See Figure 11.4.
NOTE: The order of parts in this group are bear-
ing housing, bearing, shim and spacer.
11.5. Tip the unit back and down so it rests on the
drive housing.
11.6. Using a 1/2” socket, remove the six AB Screws
and bell washers securing the auger assembly
to the sides of the auger housing. See Figure
11.6.
Figure 10.1
Lock Bolt
Auger Pulley
Figure 10.2
Lubricate under idler arm
Flat Idler Pulley
Tension Spring and Cable
Extension Spring
Figure 11.4
Bearing Housing
Hex Nuts and Lock Washers
Figure 11.6
AB Screws

Model 380 Two Stage Snow Thrower
7
11.7. Remove the complete auger assembly from the
auger housing. See Figure 11.7.
11.8. Inspect the hex flange bearings and bearing
housings for any wear or damage
11.9. If not removed previously, remove the shim and
spacer from the worm shaft. See Figure 11.9.
NOTE: The auger housing holes are elongated
to allow auger alignment during reassembly.
NOTE: When reassembling be careful not to
over torque and strip the bearing hub housing
holes.
Figure 11.7
Auger Assembly
Hex Flange Bearing and Bearing Housing
Figure 11.9
Shim and Spacer on Worm Shaft
12. SPIRAL ASSEMBLY REMOVAL
12.1. Remove the auger and impeller assembly from
the housing. Refer to Section 11.
12.2. Using a 1/2” socket and a box end wrench,
remove the hex lock nut and shear bolt from the
spiral assembly and auger drive shaft. See Fig-
ure 12.2.
12.3. Slide the spiral augers off the shaft and mark the
spiral for left or right side.
NOTE: It is possible to install the auger spirals
backwards. If necessary, refer to the illustrated
parts diagram for proper orientation.
NOTE: During disassembly note the location of
the flat washer on the gearbox side of the spiral
and flange bushings on both ends of the spiral.
Figure 12.2
Hex Lock Nut and Shear Bolt

Model 380 Two Stage Snow Thrower
8
13. IMPELLER REMOVAL
13.1. Remove the auger and impeller as described in
Section 11.
13.2. Using a 3/16 punch and hammer, remove the
front spiral pin securing the impeller to the worm
shaft. See Figure 13.2.
13.3. Slide the impeller on the worm shaft towards the
reducer housing to gain access to the rear spiral
pin.
13.4. Using a 3/16 punch and hammer, remove the
rear spiral pin. See Figure 13.4.
13.5. Remove the impeller from the worm shaft.
14. REDUCER TRANSMISSION
14.1. The reducer can be serviced. It can also be pur-
chased as an assembly. See Figure 14.1.
NOTE: On the top of the gearbox is inspection
and access hole for adding grease when and if
required. Remove the rubber grommet from the
lubrication port.
15. REDUCTION TRANSMISSION DISASSEMBLY
15.1. Using a 3/8” socket, remove the 5 TT screws
securing the reducer halves together. See Fig-
ure 15.1.
Figure 13.2
Impeller
Spiral Pin
Figure 13.4
Rear Spiral Pin
Figure 14.1
Reducer Transmission
Rubber Grommet
Figure 15.1
5 TT Screws

Model 380 Two Stage Snow Thrower
9
15.2. Separate the housing halves using a putty knife.
See Figure 15.3.
15.3. Inspect all internal parts for wear or damage.
NOTE: before assembly, clean off all of the ultra-
gray sealant on both sides of the gearbox hous-
ing. Use ultra gray to reseal the housing before
assembly.
16. AUGER CABLE REPLACEMENT
16.1. Using two 7/16”inch wrenches loosen the two
hex nuts attaching the auger control cable to the
bracket on the left hand drive housing. See Fig-
ure 16.1.
Figure 15.3
Ultra Gray
Figure 16.1
Hex Nuts
Auger Control Cable
16.2. Spin the inner nut off the end of the control cable
and slide the cable out of the bracket.
16.3. Remove the spring from the auger bracket.
16.4. Using a ½” inch socket and a ½” inch box
wrench loosen the hex nut securing the cable
bracket to the left hand handle bar. See Figure
16.4.
16.5. Remove the cable from the bracket and remove
the “Z” fitting from the bail.
16.6. Slide the cable through the plastic tie and plastic
mounting grommet on the frame.
16.7. Replace in the reverse order of disassembly.
Figure 16.4
Cable bracket

Model 380 Two Stage Snow Thrower
10
17. DIRECTIONAL DISCHARGE CHUTE ASSEM-
BLY REMOVAL.
17.1. Turn the discharge chute until it faces to the
right. See Figure 17.1.
17.2. Using a screwdriver, pry the clasp on the chute
assembly collar to release the clasp. See Figure
17.2.
17.3. Pry the lower inner clasp to release the collar.
See Figure 17.3.
17.4. Remove the collar.
17.5. Lift off the discharge chute
NOTE: During assembly make sure to position
the collar into the detent spring. Take time to fit
upper and lower flanges on the collar around the
chute flanges. This will fit without forcing.
18. REMOVAL OF THE AUGER IDLER BRACKET
18.1. Remove the belts as described in Section 4.
18.2. Remove the wheels as described in Section 7.
18.3. Remove the transmission as described in Sec-
tion 9.
Figure 17.1
Discharge chute facing right
Figure 17.2
Chute Collar
Clasp
Figure 17.3
Lower Clasp
Assembly Detail
Chute Collar
Detent Spring

Model 380 Two Stage Snow Thrower
11
18.4. Remove the auger pulley as described in Sec-
tion 10.
18.5. Remove the auger and impeller as described in
Section 11.
18.6. Using a 15/16” socket on the Idler side and a 9/
16” socket on the impeller side, remove the
shoulder screw and flange lock nut securing the
idler to the auger housing. See Figure 18.6.
18.7. Disconnect the extension spring from the idler to
the housing.
18.8. Remove the Idler bracket.
Figure 18.6
Shoulder Screw
(Flange Lock Nut on
underside of housing)
19. ENGINE PULLEYS
NOTE: If there is reason to disassemble the
engine pulleys, pay attention to the shape and
orientation of the pulleys and spacers for reas-
sembly.
20. CARBURETOR BOWL DRAIN
This model has a spring loaded drain for the float bowl.
It can be used to drain water or old fuel from the float
bowl. See Figure 20.0.
Auger Pulley
Drive Pulley
Figure 20.0
Carburetor Bowl Drain