McCulloch 32CC TRIMMER User manual

Brand: McCulloch

Model: 32CC TRIMMER

Type: User manual

Service Manual

IMPORTANT: READ SAFETY RULES AND INSTRUCTIONS CAREFULLY

PRINTED IN USA

FORM NO. 769-00942

This Service Manual is not a substitute for the Operator’s Manual. You must read, understand

and follow all of the directions in this manual as well as the Operator’s Manual before working

on this power equipment.

(10/2003)

32cc String Trimmer

Power Head

MCCULLOCH CORPORATION P.O. BOX 31567, TUCSON, AZ 85751-1567

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

MTD Products LLC - Product Training and Education Department

1. INTRODUCTION

North American distribution rights to the McCulloch

product line are new to MTD for the 2004 season. The

trimmers are similar in some ways to the MTD South-

West (RYOBI) products that we have offered for the

past three years.

The architecture of both units is based on a cantilever

crankshaft. The McCulloch is piston ported, while the

MTDSW engine has a reed valve. Some of the service

techniques are similar, but not identical.

2. TRIMMER HEADS

2.1. One trimmer head available on the McCulloch

products is nearly identical to the MTDSW Tap-

N-Go. The operating principle is the same, but

the parts are different enough that they are not

fully interchangeable. See Figure 2.1.

2.2. There is also a McCulloch version of the large

tap-n-go head. It is used on the straight shaft

trimmers, and rotates in the opposite direction of

the small one.

Figure 2.1

McCulloch version

of small tap-n-go

2.3. Another trimmer head that is used on McCulloch

string trimmers resembles a cross between the

MTDSW Speed Spool and the MTDSW Tap-N-

Go head. See Figure 2.3.

2.4. A refill consists of 15’ - 20’ of .080” trimmer line.

2.5. To install line, cut it to length. Two equal-length

half-portions may be used, or one full length line

may be installed, then trimmed after installation.

See Figure 2.5.

Figure 2.3

McCulloch trimmer head with

simplified loading

Figure 2.5

Single-length method

McCulloch 32cc Trimmer

2.6. Align the arrows on the spool with the arrows on

the housing. See Figure 2.6.

2.7. Insert a length of trimmer line through each eye-

let. There are two sheaves for line in the spool,

separated by a narrow groove. The line must

enter the narrow groove. See Figure 2.7.

2.8. From the eyelet, the line will be channeled up

under the bump knob by a set of ramps in the

spool. See Figure 2.8.

2.9. The ends of the line are looped-through the

anchors to hold them in place, then pulled-tight.

NOTE: With the arrows aligned, the line can also

be installed from the inside-out, by removing the

bump knob.

2.10. The final step is to rotate the spool in the direc-

tion indicated by the arrows, drawing the line into

the head. See Figure 2.10.

2.11. Stop winding when each end of the line is about

6” long.

2.12. Press the bump knob and pull on the line to

manually test the trimmer head. Do not push the

housing off it’s seat while testing.

Figure 2.6

Housing

Spool

Arrows

(marked for

clarity)

Figure 2.7

Eyelet

Center

groove

Figure 2.8

Ramps

Bump knob

removed for

clarity

Bump knob

Anchors

Figure 2.10

Inset: arrow on spool, marked

for clarity

McCulloch 32cc Trimmer

2.13. If repair is required, remove the bump knob, and

withdraw the spool. See Figure 2.13.

2.14. Check for: tangled line, damaged tabs on the

spool, worn ribs on the spool, missing spring,

broken ratchet wedges.

2.15. Replace the spool if it is worn or damaged.

NOTE: Bump knobs are a wearable item, and

are replaced in the course of normal use.

2.16. The housing is not fastened to the boom. It sim-

ply rests over a hexagonal drive collar.

See Figure 2.16.

Figure 2.13

Spring

Tab s

Ratchet wedges

Ribs

Figure 2.16

Drive collar

2.17. The ratchet wedges can be serviced by remov-

ing the three screws holding the black cover to

the top of the housing. See Figure 2.17.

2.18. Carefully remove the springs, and pull out the

wedges. See Figure 2.18.

Figure 2.17

Cover

Holes for screws

Small springs behind

Figure 2.18

Spring seats over

post on back of wedge

One rounded side,

insures correct orientation

McCulloch 32cc Trimmer

2.19. When properly installed, the wedges should be

spring loaded. They retract when the ribs on the

back of the spool pass them, then extend to

keep the spool from rotating backwards.

See Figure 2.19.

3. RECOIL STARTER

3.1. Next to the cutting head, this is probably the

most common service item on the trimmer. It is

similar in principle to the MTDSW starter, but the

routing of the throttle and stop switch cables

necessitates a slightly different approach.

3.2. The throttle trigger, stop switch, and grip can all

be removed from the boom in unit with the

power-head. See Figure 3.2.

3.3. To separate the powerhead from the boom,

remove the screw at the top of the grip using a T-

25 driver, then withdraw the boom.

See Figure 3.3.

3.4. Remove the air filter cover using a T-25 driver to

gain access to the connection between the throt-

tle cable and the throttle arm on the carburetor.

See Figure 3.4.

Figure 2.19

Spring loaded

ratchet wedges

Figure 3.2

Screw holds grip

and Throttle housing

to boom

Positioning mark

Figure 3.3

grip slip off of boom

Trigger housing and

Screw

removed

Figure 3.4

Air filter

cover

McCulloch 32cc Trimmer

3.5. Disconnect the throttle cable from the carburetor

by unhooking the Z-fitting at the carburetor end

of the cable. See Figure 3.5.

3.6. After the powerhead is separated from the

boom, and the throttle cable is slackened, the

housing that contains the stop switch and throttle

trigger can be separated from the grip.

NOTE: Alternatively, instead of removing the

complete powerhead and grip from the boom,

the clutch housing can be separated from the

starter housing. If this approach is taken, the

stop switch wires must be disconnected as the

two sections are separated. The throttle cable

will pull out of the starter housing and clutch

housing as the powerhead is removed. Because

of the difficulty of routing the throttle cable back

through the housings, a wire or string should be

connected to the z-fitting so that the throttle

cable can be “fished” back into place.

Figure 3.5

Z-fitting on end of

throttle cable

Throttle arm

on carburetor

3.7. Remove the two screws from the trigger housing

cover using a T-15 driver. See Figure 3.7.

3.8. Push the front part of the housing forward to

remove it. See Figure 3.8.

3.9. The throttle trigger will be released from its pivot

point, and the stop switch will remain with the

rear portion of the housing.

NOTE: The stop switch contacts two rub strips to

ground-out the ignition module. One rub strip is

connected to the primary windings of the mod-

ule, the other leads to ground.

Figure 3.7

Trigger housing

Trigger housing cover

Stop switch

Trigger housing

cover screws

Figure 3.8

Grip

slips out of grip

Trigger housing

Stop switch mounted

on cover plate

Stop switch

contacts

McCulloch 32cc Trimmer

3.10. The trigger housing can be pulled-free of the grip

after the trigger and rear housing are removed.

See Figure 3.10.

NOTE: The throttle cable and stop switch wires

are held in adjacent channels by a white plastic

sleeve that is inserted in the grip.

3.11. Pull the white sleeve out of the grip and unplug

the stop switch wires from their connections to

the contact strips in the trigger housing.

See Figure 3.11.

3.12. The grip and clutch housing can be separated

from the engine by removing the four screws

that fasten them together, using a T-25 driver.

See Figure 3.12.

3.13. Remove the grip and clutch housing, and unplug

the stop switch wires from their connections on

the engine. See Figure 3.13.

NOTE: Pay attention to the routing of the throttle

cable and stop switch wires.

3.14. Disconnect the H.T. lead from the spark plug.

and remove the spark plug using an 5/8”

wrench.

3.15. Pack the cylinder full of starter rope to act as a

piston stop.

Figure 3.10

Channel for

stop switch wires

Channel for

throttle cable

White plastic

sleeve

Figure 3.11

Remove

sleeve

Figure 3.12

Clutch housing

Stop switch wires

Starter

housing

NOTE:The grip is

integral with the

clutch housing

Figure 3.13

Channel for stop

switch wires

Channel for

throttle cable

McCulloch 32cc Trimmer

3.16. Remove the clutch drum using a T-25 driver.

See Figure 3.16.

3.17. After the clutch drum is removed, the clutch rotor

can be removed using MTDSW clutch removal

tool # 791-180919. See Figure 3.17.

NOTE: a hammer and soft drift can be used if

the MTDSW tool is unavailable.

Figure 3.16

Clutch drum

Recoil rope used

as a piston stop

Figure 3.17

Crankshaft

Clutch rotor

Spade terminals

for stop switch wires

Throttle cable

3.18. The flat side of the clutch rotor seats against a

tube that surrounds the crankshaft.

See Figure 3.18.

3.19. With the clutch rotor removed, the starter hous-

ing can be removed.

3.20. Take out the four screws holding the starter

housing to the engine using a T-25 driver.

See Figure 3.20.

Figure 3.18

Flat side of clutch rotor

faces starter housing

Tube

Figure 3.20

Starter housing

Screws

McCulloch 32cc Trimmer

3.21. Unplug the stop switch wires from the ignition

module as the starter housing is removed from

the engine. See Figure 3.21.

NOTE: There are two sets of stop switch wires.

The set inside the starter housing connects to

the ignition module. The set of stop switch wires

in the clutch housing connects the set inside the

starter housing to the stop switch.

3.22. The throttle cable is best left in the starter hous-

ing as it is removed. This can be done by simply

rotating the starter housing out of the way.

See Figure 3.22.

3.23. Alternatively, the throttle cable could be discon-

nected from the engine by squeezing the tabs,

and removing it along with the starter housing.

See Figure 3.23.

NOTE: If a throttle cable needs replacement,

attach a line to the carburetor end of the old

cable before removal, to facilitate “fishing” the

replacement cable into place.

3.24. Remove the baffle from the starter housing using

a T-25 driver.

NOTE: The starter pulley is held in place by the

baffle. There are no other fasteners on it.

3.25. Once the baffle is removed, the starter pulley

can be carefully lifted out to access the recoil

spring. See Figure 3.25.

Figure 3.21

Stop switch wires

Starter housing

Ignition module

Figure 3.22

Starter housing removed

Throttle cable

Figure 3.23

Squeeze tabs

Figure 3.25

Baffle

Posts

Stop

switch

wires

McCulloch 32cc Trimmer

NOTE: If the starter rope is not broken, it will be

necessary to relieve tension from it before

removing the starter pulley.

3.26. Examine the pulley and spring for wear and

damage. Look for straightened ends on the

spring. Look for rounded edges on the teeth of

the starter pulley. See Figure 3.26.

3.27. When installing new starter rope, use about 6’ of

3/16 starter rope.

3.28. After the starter pulley is removed, the starter

spring can be lifted out of the starter housing,

complete with the steel cartridge that contains it.

See Figure 3.28.

3.29. There is a plastic shield that fits between the

starter pulley and the starter spring.

Figure 3.26

Starter pulley

Spring cover

Spring ends

Figure 3.28

Starter

spring in

cartridge

Notches engage

end of spring

Plastic shield

3.30. As the starter is reassembled, apply a sparing

amount of white lithium grease to the friction sur-

faces of the starter pulley.

3.31. Pay close attention to the routing of the stop

switch wires.

3.32. Wind tension onto the starter rope after the pul-

ley is in place, but before the baffle is installed.

It will be necessary to use caution nut to pull

upward on the rope, dislodging the pulley from

the spring. Light thumb pressure on top of the

pulley is advised. See Figure 3.32.

3.33. If the starter pawls on the flywheel are worn or

damaged, remove the flywheel. See Figure 3.33.

NOTE: In particular, look for rounded edges on

the corners of the pawls that engage the teeth

on the pulley.

Figure 3.32

Figure 3.33

Tube

Nut

Flywheel

Starter pawls

Spacer

McCulloch 32cc Trimmer

3.34. Remove the spacer and tube from the crank-

shaft.

3.35. Remove the nut from the crankshaft using a

deep 11/16” socket. See Figure 3.35.

3.36. Pry up on one thick section of the flywheel, and

strike the opposite side with a soft dead-blow

hammer. See Figure 3.36.

3.37. Lift the flywheel off of the crankshaft, using cau-

tion not to lose the flywheel key.

3.38. If the flywheel has any chips, cracks, or broken

vanes, discard it. Re-using a damaged flywheel

presents a burst hazard.

3.39. If the pawls are damaged, they are available as

a pair, with mounting hardware, in kit form.

See Figure 3.39.

3.40. Release the retainers on the back side of the fly-

wheel to remove the starter pawls.

See Figure 3.40.

3.41. After replacing the pawls or the flywheel, care-

fully seat the key and flywheel back on the

crankshaft.

3.42. Install the nut, and torque it to xx in-lbs., then

place the spacer and tube back over the crank-

shaft.

Figure 3.35

Tube

Spacer

Crankshaft

Nut

Figure 3.36

Tapered seat

Key

Threads

for nut

Threads for

clutch rotor

Figure 3.39

Starter pawl

Damaged edge

Figure 3.40

Pawl retainers

McCulloch 32cc Trimmer

3.43. Removing the starter housing will also allow

access to the ignition module. If the ignition

module is removed for any reason, the air-gap

must be adjusted with the flywheel securely fas-

tened. See Figure 3.43.

3.44. Set the air gap to .014” using a non-magnetic

feeler gauge.

3.45. After the starter is assembled, carefully position

the starter housing, throttle cable, and stop

switch wires, and install the starter housing to

the engine. See Figure 3.45.

Figure 3.43

Check air gap

Male spade terminals

for stop switch wires

Figure 3.45

Stop switch wires

Throttle

cable

3.46. As the starter housing goes-on, connect the

short lengths of stop switch wire that are inside

the starter housing to the ignition module, and

clip the throttle cable into the hole in the engine

case. See Figure 3.46.

3.47. Secure the starter housing to the engine.

3.48. Install the clutch rotor and drum.

See Figure 3.48.

Figure 3.46

Throttle cable

Figure 3.48

McCulloch 32cc Trimmer

3.49. Connect the stop switch wires in the clutch hous-

ing to the male spade terminals on the ends of

the stop switch wires in the starter housing, and

position the throttle cable as the clutch housing

is lowered into place. See Figure 3.49.

NOTE: The wires and cable should be posi-

tioned as they were in Figure 3.13.

3.50. Secure the clutch housing to the starter housing.

3.51. Position the throttle cable and stop switch wires

as they were in Figure 3.11.

3.52. Insert the white plastic sleeve into the grip.

3.53. Connect the carburetor end of the throttle cable,

then assemble the throttle trigger housing.

3.54. Install the power-head on the boom.

4. EXHAUST

If the fuel/oil mixture is too rich, the exhaust port and

muffler may accumulate deposits of carbon. These

deposits will hinder high-R.P.M. engine performance

and increase operating temperatures. Eventually, they

may lead to a no-start situation. There is a character-

istic “flat” tone to the exhaust noise that accompanies a

blocked exhaust.

4.1. The engine cover must be removed to gain

access to the muffler. See Figure 4.1.

4.2. Disconnect the high tension lead form the spark

plug.

4.3. Remove the air filter cover using a T-25 driver.

See Figure 4.3.

4.4. This will allow access to the screw that secures

the carburetor side of the engine cover.

Figure 3.49

Figure 4.1

Air filter cover

Engine cover

Engine

cover

screw

D-shaped

washer

Figure 4.3

Air filter

Engine

cover

screw

McCulloch 32cc Trimmer

4.5. Remove the three screws that secure the engine

cover, using a T-25 driver. See Figure 4.5.

NOTE: the screw on the exhaust side of the

engine has a plastic washer. The screw on the

back side of the engine has a round steel

washer. The screw on the carburetor side of the

engine cover has no washer.

4.6. With the engine cover removed, the spark arres-

tor and muffler are accessible. See Figure 4.6.

4.7. The spark arrestor is easily removed for cleaning

or replacement using a phillips head screw-

driver, or a nut driver.

NOTE: The spark arrestor consists of a screen,

a cover, and a screw. It is available as a kit.

Figure 4.5

Screw

Round

washer

Figure 4.6

Spark arrestor

Muffler

4.8. The muffler can be easily removed by unhooking

the spring and bale that retain it. See Figure 4.8.

4.9. Rotate the bale upward to liberate the muffler,

muffler gasket, and port gasket.

See Figure 4.9.

NOTE: The exhaust port provides an ideal win-

dow into the cylinder to inspect the condition of

the piston skirt and the cylinder wall.

4.10. Bale fits just beneath the largest cooling fin on

the cylinder, and hooks into the cylinder. Rotate

it to unhook it.

4.11. Clean the muffler and port if necessary, using

care not to damage the piston or knock carbon

into the cylinder.

Figure 4.8

Hook on

cylinder

Bale

Spring

Figure 4.9

Exhaust port

piston skirt

McCulloch 32cc Trimmer

4.12. Install the muffler using a new gasket.

See Figure 4.12.

4.13. Install the engine and air filter covers, and con-

nect the high tension lead to the spark plug.

4.14. Test run the unit before returning it to service.

NOTE: The engine can be test-run briefly with

the muffler removed. Hearing protection is

strongly suggested. Extended running (30 sec-

onds or more) is not recommended without the

engine cover and muffler in place.

5. FUEL SYSTEM

Carburetor repair is beyond the scope of this manual,

but service information is available from Walbro and

Zama, the manufacturers whose carburetors are used

on McCulloch products.

5.1. The fuel filler cap contains a polymer “stone”

tank vent. If it becomes blocked, the tank may

pressurize when heat-soaked, flooding the

engine.

5.2. The opposite situation may occur if the engine is

run with a blocked tank vent. Air will be unable

to enter the tank to replace the fuel that is con-

sumed by the engine. This will create a vacuum,

and fuel starvation will occur. See Figure 5.2.

5.3. The air filter cover is easily removed using aT-25

driver. See Figure 5.3.

Figure 4.12

exhaust gasket

Figure 5.2

Fuel cap vent

Wet-bulb

primer

Figure 5.3

McCulloch 32cc Trimmer

5.4. It is important to clean and re-oil the air filter

every 10 hrs. of operation, as described in the

Operator’s Manual. Failure to do so will cause a

loss of performance, and may allow dirt inges-

tion by the engine.

5.5. There is a wet-bulb primer in the return line from

the fuel chamber in the carburetor to the fuel

tank. See Figure 5.3.

NOTE: All current McCulloch products, including

chainsaws, use the same primer bulb assembly.

5.6. There are two barbs on the primer bulb assem-

bly. The longer one goes connects to the line

that returns to the tank. The shorter one con-

nects to the fuel chamber in the carburetor.

5.7. A check valve in the primer bulb assembly

allows the fuel to move in one direction only. If

fuel moves in both directions, replace the primer.

5.8. The primer clips into a bracket on the air filter

box. Squeeze the tabs together to remove it.

5.9. The fuel feed line and fuel return line enter the

tank through a black rubber grommet. The

grommet can be easily pried-out or the tank for

access to the fuel filter.

Figure 5.5

Line to carb.

Return

line

5.10. If it is necessary to remove the fuel tank, the air

filter cover and engine cover must be removed

as described elsewhere in this section.

5.11. The case plug and case plug reinforcement plate

must be removed using a T-25 driver.

See Figure 5.11.

5.12. The fuel tank is locked into place between a pair

of bosses on the crankcase plug and a pair of

bosses on the engine shroud.

5.13. Rubber insulators fit between the bosses and

the tank, protecting the tank from abrasion.

5.14. Always replace the crankcase plug gasket when

it is removed. Failure to do so may create a

crankcase air leak, causing poor low R.P.M. per-

formance and creating a lean fuel/air mixture.

5.15. Any time that carburetor service is required, the

rest of the fuel system should be inspected as

well. This includes: air filter, fuel filter, fuel lines,

primer bulb, insulator block, insulator block gas-

ket, carburetor gasket.

Figure 5.11

Case plug

reinforcement

plate

McCulloch 32cc Trimmer

McCulloch 32CC TRIMMER User manual

McCulloch 32CC TRIMMER User manual

McCulloch 32CC TRIMMER User manual

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