Tecumseh Overhead Valve Manual

5/26/2018 Tecumseh Overhead Valve Manual

1/94

This manual covers engine models:

OHH50 - 65, OHHSK50 - 130, OHV11 - OHV17, OVM120,

OVRM40-675, OVRM120, OVXL/C120, OVXL120, OVXL125.

Other illustrated Tecumseh 2-Cycle Engine, 4-Cycle Engine and

Transmission manuals; booklets; and wall charts are available

through Tecumseh.

For complete listing write or call

CONTAINS SEARS CRAFTSMAN CROSS REFERENCE

4-CYCLEOVERHEAD

VALVEENGINES

T E C H N I C I A N ' S H A N D B O O K

TECUMSEH

Small Eng
http://www.barrettsmallengine.com/http://www.barrettsmallengine.com/


2/94


3/94


4/94

CHAPTER 1 GENERAL INFORMATION

THIS ENGINE MEETS 1995-1998

CALIF. EMISSION REGULATIONS FORULGE ENGINES AS APPLICABLE

FUEL: REGULAR UNLEADED OIL : USE SAE 30

OHV 125 203000A (D)

RTP358UIG2RA

358cc 3057D


5/94

2


6/94


7/94


8/94


9/94


10/94


11/94

ALTERNATE LOCATIONFOR MANUFACTURINGNUMBER

CARBURETORDATE CODE

MANUFACTURINGNUMBER

FLATDOWN

CHOKE PLATE

894F5

894F5


12/94

THROTTLESHUTTER

IDLE AIRBLEED MAIN AIR

BLEED

CHOKESHUTTER

INLET NEEDLEAND SEAT

FLOAT

MAIN

ADJUSTMENT

IDLEADJUSTMENT

MAIN NOZZLE

PRIMER BULB

VENT

VALVE OPEN

VALVE CLOSED

FUEL SUPPLY PULSE LINETO CRANKCASE

VALVE CLOSED

VALVE OPEN

CARBURETOR FITTING

DIAPHRAGM

FILTER

AIR BLEED

ATMOSPHERICVENT

CRANKCASE PRESSURE

ATMOSPHERIC PRESSURE ACTING

ON DAMPING DIAPHRAGMFUEL FLOW

CRANKCASE SUCTION AND

FLOW DIRECTION

ATMOSPHERIC PRESSURE

ACTING ON DAMPING

DIAPHRAGM

SUCTION FUEL FLOW DIRECTION


CAUSED FUEL FLOW

TYGON TUBE

EXTERNAL VENT

PRIMER BULB

MAIN JETMAIN NOZZLE

INTERNAL VENT


13/94


14/94

IDLE JETCAST BUT NOTMACHINED

MIXING WELLCAST BUT NOTMACHINED

CAPPED FIXEDIDLE JET

LOW IDLEMIXTURE SCREWMAY BE ADJUSTABLE OR FIXED

CAP


15/94


16/94

SERIES "3" & "4"

IDLE MIXTURESCREW

MAINMIXTURESCREW

SERIES "9"

SERIES "7"

SERIES "8"

WALBRO LMK

CAPPEDFIXEDIDLE JET

SERIES "10"


17/94

CHOKEEND

THROTTLEEND

LONG ENDOF CLIP

CLIPOPEN ENDOF CLIP


18/94

WELCH PLUG TOBE REMOVED

PIERCE PLUGWITH TIP

DO NOT ALLOWCHISEL POINTTO STRIKECARBURETORBODY ORCHANNELREDUCER

ABOUT 1/8"(3.175 mm)WIDE

BALL PLUG IDLE FUEL PASSAGEREDUCTION ROD INSIDE

BRASS OR BALL PLUG

HIGH SPEED JET

ATMOSPHERICVENT

WALBRO LMK SERIES

PRY OUTPLUG

SMALLCHISEL

SMALL CHISEL


19/94

FUEL-INLET

IDLE FUELTRANSFERPASSAGE

FUEL-METERINGPORT

ONE-HOLE TYPE TW0-HOLE TYPE

11 / 64" (4.36 mm)

FLOATSETTING

FLOAT

FLOAT HINGEAND AXLE

ADJUSTING TAB INLET NEEDLEAND SEAT

RETAINER NUT

SPRING

"O" RING

BRASS WASHER

HIGH SPEEDADJUSTMENTSCREW


20/94

SERIES 8, 9 & 10

NEEDLE &SEAT

FLOAT

SPRING

FLOAT HINGEPIN

SEATRETAININGRING

IDLE RESTRICTION

BOWL

'O' RING

MAIN JET

GASKET

BOWL RETAINERBOWL DRAIN

MAIN JETSPRING

MAIN NOZZLEEMULSION

"O" RINGPOSITIONED INGROOVE

CHOKE SHAFT

THROTTLE SHAFT

CHOKE DUSTSEAL

CHOKE RETURNSPRING

BOWL NUT

BOWL NUT WASHER

FLOAT BOWL

"O" RING

FLOAT FLOAT SHAFT

SCREWFUEL FITTING

INLET NEEDLE

THROTTLE SHUTTER

CHOKESHUTTER

WELCH PLUG

TENSION SPRING

IDLE MIXTURESCREW

THROTTLE DUST SEAL

THROTTLE RETURN SPRING

IDLE SPEED SCREW

THROTTLE SHAFT & LEVER

THROTTLE RETURN SPRING

DUST SEAL WASHER

DUST SEAL

THROTTLESHUTTERSCREW

FUEL FITTING

PRIMER BULB/RETAINERRING

PRIMER BULBFILTER

ATMOSPHERIC VENTWELCH PLUG

"O" RING

SPRING CLIP

FLOAT SHAFT

SEAT AND CLIP INLETNEEDLE

FLOAT

FLOAT BOWL

BOWL NUT WASHER

HIGH SPEED BOWL NUT

THROTTLE SHUTTER

SEATNEEDLE

SPRING CLIP

HINGE PIN

"O" RING

NOZZLE

BOWL

JET/BOWL NUT

WASHER

WALBRO LMK SERIES 6

"O" RINGPOSITIONED INGROOVE

SERIES 7


21/94

THROTTLELEVER

THROTTLEPLATE

WALBRO LMK SERIES

THROTTLE LEVER

THROTTLE PLATE

SERIES 7

DUST SEALS

NEW WELCH PLUG SAME ORLARGER

DIAMETER OFPLUG HOLE

FLAT END PUNCH

On Walbro LMK and Series 7 carburetors, install the

throttle return spring on the throttle shaft with thesquared end up. Slide the foam dust seal over thespring. Insert the throttle lever assembly into thecarburetor body with both tangs of the return springon the left side of the center boss (viewed from throttleend) and the flat side of the shaft toward the carburetormounting flange. Install the throttle shutter to thethrottle shaft using notes or marks to place the shutteras originally found (Series 7 must have the line on theshutter at the 3 o'clock position) (diag. 44).

Always use new throttle shutter screws whenreinstalling. Install the screws so they are slightlyloose. Apply light downward pressure on the throttle

shaft and rotate it clockwise to seat the throttle shutterin the bore, then tighten the throttle shutter screws.Check for binding by rotating the throttle shaft. Ifnecessary, adjust the throttle shutter by loosening andrepositioning the shutter, then retighten the screws(diag. 45).


22/94

FLOAT HINGE PIN

NEEDLE &SEAT

SEAT RETAININGRING

FLOAT

IDLE RESTRICTION

MAIN JET

MAIN JET SPRING

"O" RING

SPRING

BOWL RETAINER

BOWLDRAIN

BOWL

MAIN NOZZLE EMULSION

"O" RING POSITIONED INGROOVE

GASKET

RETAINER NUT

SPRING

"O" RING

BRASS WASHER

HIGH SPEEDADJUSTMENTSCREW

STRAINER

SOME INLET FITTINGSPRESS IN PARTIALLYTHEN APPLYLOCTITE

FLAT DOWN

CHOKE PLATE

SPRINGHOOKUPS


23/94

SEAT

5/32" (3.969 mm)FLAT PUNCH

THROTTLEEND

CLIP

CHOKEEND

PUSH IN UNTILSEAT RESTS ONBODY SHOULDER

IF YOUR CARBURETORHAS A STEEL SEATRETAINING RINGRE-INTSALL AFTERSEAT INSTALLATION

INSERT THISFACE FIRST

INLET NEEDLESEATS AT THISPOINT

OPEN END OF CLIP

LONG ENDOF CLIP

OPEN ENDOF CLIP

CLIP

POINTS TOWARDTHE CHOKE END

LONG ENDOF CLIPPoints toward chokeend

Points toward choke end

SERIES 7 WALBRO / LMK


24/94

VALVE OPEN

VALVE CLOSED

FUEL SUPPLY PULSE LINETO CRANKCASE

VALVE OPEN

CARBURETOR FITTING

DIAPHRAGM

FILTER

AIR BLEED

ATMOSPHERICVENT

CRANKCASE PRESSUREATMOSPHERIC PRESSURE ACTING

ON DAMPING DIAPHRAGM

FUEL FLOW

CRANKCASE SUCTION ANDFLOW DIRECTION


ACTING ON DAMPINGDIAPHRAGM

SUCTION FUEL FLOW DIRECTIONATMOSPHERIC PRESSURE

CAUSED FUEL FLOW

VALVE CLOSED


25/94

GOVERNOR GEAR

WEIGHTS

THROTTLE

SPRING

GOVERNORSPOOL

GOVERNOR SHAFT


26/94

GOVERNORCLAMPSCREW

PUSHLEVER TOWIDE OPENTHROTTLE

TURN CLIP COUNTERCLOCKWISE ON ALL VERTICAL

SHAFT ENGINES EXCEPT VLV & VLXL. CLOCKWISEON ALL HORIZONTAL SHAFT ENGINES EXCEPTOHH,OHSK 50,55 & OHM, OHSK 110,120.

SHIM

670297 (modified)

SHAFT BOSS

GEAR

WASHER

OHH SERIES - OLD STYLE

ROTATE CLAMPCOUNTERCLOCKWISE

THROTTLE OPEN

(PUSH COUNTERCLOCKWISE)

GOVERNOR

ROD

GOVERNOR

CLAMP

GOVERNOR

SCREW

STANDARD

LOCATION

GOVERNOR

LEVER

OHH SERIES - NEW STYLE


27/94

SHAFT

RETAININGRING

WASHER

SHAFT

GEAR ASSY.(GOV.)

GEAR ASSY.(GOV.)

WASHER

SPACER

WASHER

SPOOL

SHAFT

11

WASHER

SHAFT

SPOOL

GEAR ASSY.(GOV.)

RETAININGRING

WASHER

GEAR ASSY.(GOV.)

RETAININGRING

WASHER

SPOOL

SPACER

RETAININGRING

SPOOL

RETAININGRING

WASHER

GEAR ASSY.(GOV.)

109

SPOOL

OVRM TYPE I OVRM TYPE II MEDIUM FRAME OHH / OHSK50-70OVM / OHV / OHM

OHSK80-130

SERVICED AS ASSEMBLY

UPSET

SHAFT

NOTE; SPACERMAY BE PART

OF THE GEARASSEMBLY.


28/94

HIGH SPEED STOP


29/94

NOTE: ON REMOTECONTROL THISWILL NOTBE PRESENT

LOW SPEED ADJUST

HIGH SPEED ADJUST

OVRM OVRM

OVRM SNAP IN CONTROL

LOW SPEED TAB HIGH SPEED TABHIGH SPEEDPIN POSITION

DECREASE

INCREASE

OHH RV CONTROL

GOVERNOR SPRINGGOVERNED IDLE LINK

OHH REMOTE & MANUAL OHH FIXED SPEED

WINTERAPPLICATIONCONTROL

HIGH SPEEDADJUSTMENT

BEND TO ADJUST SPEEDDECREASE INCREASE

GOVERNEDIDLE LINKAND

ADJUSTMENT

HIGH SPEED ADJUST

OH / OHSK CONTROL

OHSK / OHM CONTROL

GOVERNEDHIGH SPEEDADJUST

BEND

GOVERNED

HIGH SPEEDADJUST

GOVERNED IDLE TAB

GOVERNED IDLE SCREW

INCREASE DECREASE

T-10THROTTLE CRACK SCREW

T-10THROTTLE CRACK SCREW

CORRECT BUSHINGINSTALLATION DEEPSIDEHERE


30/94

OHV11 - 17 SPEED CONTROLOVM / OVXL GOVERNOR OVERRIDE

HIGHSPEEDADJUST

GOVERNED IDLEADJUST


31/94

OHV VERTICAL CONTROL

OHV 11 - 17 HORIZONTAL CONTROL


32/94

ROPE

HANDLE

WASHER

STARTER DOG

STARTER HOUSING

RETAINER

PULLEY ANDREWIND SPRINGASSY.

DOG SPRING

SPRING PIN

BRAKE SPRING

WASHER


33/94

LEFT-HANDKNOT

ONE PIECE ROPE RETAINER

STAPLE

ROPE

HANDLE

WASHER

STARTER DOG

STARTER HOUSING

RETAINER

PULLEY ANDREWIND SPRINGASSY.

DOG SPRING

SPRING PIN

BRAKE SPRING

WASHER


34/94

PULLEY AND REWINDSPRING ASSY.

BRAKE SPRING

STARTER DOG

DOG

SPRING

WASHER

SPRING PIN

STARTER HOUSING

HANDLEINSERT

ROPE

HANDLE

WASHER

RETAINER

ROPE

STARTERHOUSING

HANDLE

PULLEY AND REWINDSPRING ASSY.

STARTER DOG

BRAKE SPRING

DOG RETAINER

RETAINER WEDGE

STARTERHOUSING

DOG SPRING

STARTER DOG

STARTER PULLEYSPRING & COVER

LEFT-HANDKNOT

DOG SPRING

WASHER

RETAINER

WASHER

SPRING PIN


35/94

DOG RETAINER

STARTERHOUSING

DOG SPRING

STARTER DOG

STARTER PULLEYSPRING & COVER

STARTER HOUSING

SPRING PIN

BRAKE SPRING

HANDLE

DOG SPRING

STARTER DOG

ROPE

PULLEY

RETAINER SCREWCAM DOG

WASHER

HANDLEINSERT

DOG RETAINER

REWINDSPRING AND

KEEPERASSY.

"STAMPED STEEL WITH ROLL PIN"

LEFT-HANDKNOT


36/94

SPRING &KEEPER ASSY.

HOUSING

PULLEY

DOG SPRNGBRAKE SPRING

RETAINER

CENTER PIN

RETAINER SCREW

HANDLE

"STAMPED STEEL"

CENTER SCREW

HANDLE

PULLEY

BRAKE SPRING

HOUSING

CAM DOG

BRAKE WASHERRETAINER

SPRING &KEEPER

DOG SPRINGDOG

"ALUMINUM HOUSING"

STARTER HOUSING

SPRING PIN

BRAKE SPRING

HANDLE

DOG SPRING

STARTER DOG

ROPE

PULLEY

RETAINER SCREWCAM DOG

WASHER

HANDLEINSERT

DOG RETAINER

REWINDSPRING ANDKEEPERASSY.

"STAMPED STEEL WITH ROLL PIN"

LEFT-HANDKNOT


37/94

BRAKE SPRING

LEFT-HANDKNOT

REWIND SPRING

PULLEY

STARTER DOGS

STARTER DOG SPRING

STARTER DOG RETAINER

WASHER

LOCKWASHER6mm METRIC NUT

STARTER HOUSING

SPRING ANDKEEPER

PULLEY

BRAKE SPRING

STARTER DOGRETAINER SPRING

STARTER DOGRETAINER

WASHER

LOCKWASHER

CENTER SCREW

STARTER HOUSING

STARTER DOG

TYPE II

TYPE I


38/9435

END CAP

BRUSH SPRINGS

BRUSH CARD

HOUSING

ENGAGING NUTGEAR

ROTATION OF FLYWHEEL

RETAINER

SPRINGRETAINER

SPRING

END CAP

ARMATURE

BOLT

NUTS

WASHER

BRUSHES


39/9436

CATHODEANODE

HALF WAVE RECTIFIER

(SINGLE DIODE)

- VOLTAGE

+ VOLTAGE

A.C. INPUT D.C. OUTPUT

+ VOLTAGE

- VOLTAGE

D.C. OUTPUT

FULL WAVE RECTIFIER

(BRIDGE RECTIFIER)

A.C. INPUT- VOLTAGE

A.C. INPUT

+ VOLTAGE

+ VOLTAGE

+ VOLTAGE (D.C.)

BAND OR OTHERMARKING INDICATESCATHODE END


40/9437

THE LARGER THE NUMBER THE SMALLER THE WIRE

# 18

# 6


41/9438


42/9439


43/9440

CAUTION: FOLLOW ALL SAFETY PRECAUTIONS WHEN TESTING FOR A.C. VOLTAGE, ELECTRIC

SHOCK CAN KILL.


44/9441

YELLOW

#4414 BULB

ENGINE

D.C.TWO DIODES

RED

D.C. NEGATIVEOUTPUT LEAD

(BROWN D.C.)

D.C. POSITIVE

OUTPUT LEAD

(RED D.C.)

A.C.D.C.

YELLOW

YELLOWA.C.

YELLOW

GREENIGNITIONSTOP


45/9442

GREEN

DIODE

RED

IF BULB DOES NOT LIGHT OR LIGHTS WHENPOLARITY REVERSED, DISCARD DIODE.

D.C.

FUSE HOLDER

SOLDERLESS

CONNECTORSPADE

CONNECTOR


46/9443

CAUTION: BLOWER HOUSING MUST BEINSTALLED WHEN RUNNING ENGINE

A.C. VOLTMETER

5 AMP A.C.

3 AMP D.C.RED LEAD DIODE

BLACK LEAD

INSERT PROBES INTO CONNECTOR SLOTS.DO NOT REMOVE CONNECTOR WIRES.

YELLOW

RED

NOTE: D.C. OUTPUT MUST BE DISCONNECTED TOPERFORM A.C. OUTPUT TEST.


47/9444

YELLOW

DIODE

RED

YELLOW

RED

DIODE

DIODE

A.C.

D.C.

A.C.


48/9445

INSERT PROBES INTOCONNECTOR SLOTS DONOT REMOVECONNECTOR WIRES

A.C. VOLTMETER

YELLOWCAUTION: BLOWERHOUSING MUST BEINSTALLED WHENRUNNING ENGINE

RED

A.C.


49/9446

A.C. OUTPUTYELLOW

D.C. OUTPUT - RED

SOLENOID

GREEN

LIGHT

SWITCH

AMMETER

MAGNETOGROUND

BATTERY

REGULATEDD.C. OUTPUT

FUSE

YELLOW

RED

NOTE: D.C. OUTPUT MUST BE DISCONNECTED TOPERFORM A.C. OUTPUT TEST.

DOUBLESINGLE


50/9447

If equipped, the indicator light will flash if the oil levelis at or below the add mark and the engine is turnedover while attempting to start. Test by turning the engineover with the oil level below the add mark. If theindicator light does not flash, replace the indicator light.

FLOATSWITCH

LIGHTED ENGINE ON/OFF ROCKER SWITCH W/LOW OIL SHUTDOWN

TERMINALS(3)

ENGINE ON/OFF ROCKER SWITCH

TERMINALS(2)

SPACER

INDICATOR LIGHT


51/9448

GASKET

ARMATURE

THRUSTWASHER

BENDIX ASSEMBLY

RETAINING RING

DUST COVER

RETAINER &SPRING

BRUSHES


52/9449

12 VOLT 120 VOLT

BRUSHSPRINGS

CONNECTION POINT OFPOWER CORD LEADS

FIELD COILCONNECTORS

FIELD COILCONNECTORS


53/94


54/94

MOUNTING HOLES

MECHANISM FULL DOWNBEFORE SCREWS TORQUED

ELECTRIC START INTERLOCK SWITCH


55/94

CABLE CLAMPSCREW


SCREW END MUSTNOT BLOCK LEVERACTION

MOUNTING HOLES

MOUNTING HOLES


ELECTRIC START INTERLOCK SWITCH


56/94

STANDARDPLUG

OHV


57/94

MAGNETS


58/94


59/94

Normal Carbon Deposit


60/94

.0125"

(.3175 mm)


61/94


62/94

COUNTER-BALANCESHAFT

The rotary pump is driven by the camshaft. It uses alobed gear in a rotating ring to provide positive oildisplacement (diag. 9).


63/94

SHAFT

ROTOR

ROTARY PUMP

RING


64/94

ENGINE OPERATION PROBLEMS

SURGES OR RUNS UNEVENLY

Fuel cap vent obstructedExcessive engine loading

OVERHEATSENGINE KNOCKS

Associated equipment loose or

improperly adjusted

Check for excessive carbon in

combustion chamber

Loose flywheel examine key, key way

and proper flywheel nut torque

Ignition timing or

incorrect spark plug

Loose or worn connecting rod

Worn cylinder

Low oil level or wrong viscosity oil

Cooling air flow obstructed or clogged

cooling fins

Carburetor improperly adjusted or

improper RPM setting*

Ignition timing or


Carbon in the combustion chamber

Dirty carburetor or air filter

Carburetor improperly adjusted

Governor sticking, binding or improper

RPM setting

Carburetor linkage, shafts or shutters

sticking or binding

Intermittent spark, check ignition or


Oil level above full

Wrong viscosity oil

Engine cooling fins dirty causing

overheating

Breather damaged, dirty or improperly

installed

Excessive engine speed

Damaged gaskets, seals or "O" rings

EXCESSIVE OIL CONSUMPTION

Valve guides worn excessively

Worn or glazed cylinder

Piston rings worn

Lean carb setting causing overheating

(adjustable carb)


65/94

ENGINE OPERATION PROBLEMS

ENGINE MISFIRES

Improper Valve Lash

Weak valve spring

Excessive carbon build up


Ignition timing or


Valves sticking or not seating properly

Wrong or fouled spark plug

Bent crankshaft

ENGINE VIBRATES EXCESSIVELY

Attached equipment out of balance

Loose mounting bolts

If applicable counter balance not

properly aligned

BREATHER PASSING OIL

Oil level too high

Breather damaged, dirty or improperly

installed

Damaged gaskets, seals or "O" rings

Excessive RPM or improper governor

setting

Angle of operation too severe

Piston rings not properly seated or ring

end gaps are aligned

LACKS POWER

Air intake obstructed

Lack or lubrication or improper

lubrication


Exhaust Obstructed

Improper valve lash

Loss of compression (worn rings,

blown head gasket)


66/94


67/94


68/94


69/94


70/94


71/94


72/94


73/94


74/94


75/94

310

150

600

460


76/94


77/94


78/94


79/94


80/94


81/94

On engines with ball bearings in the cover,install a thrust washer (if applicable) over thecrankshaft, followed by the retaining ring.

ROTOR

SHAFT

NOTE: INSTALL OIL PUMP AFTER THE SUMP IS ON

ROTARY PUMPRING


82/94

b. Install the valves into the head, and using anew head gasket, place the head on thecylinder block. Tighten the head bolts in thenumbered sequence using 60 inch pound(6.8 Nm) increments to the specified torque.

c. Install the rocker arm housing, push rodguide plate with the legs facing up, newrocker arm studs with "O" rings under theguide plate. Install the valve box to headretaining screw using a flat washer and anew "O" ring. Tighten the screw and thestuds to the specified torque.

d. Lift each valve up until it contacts the seatand hold the valve in this position. Use a 12inch (30.5 cm) piece of fuel line and wedgeone end on each side of the valve stem

through the port opening to hold the valve.

e. Bolt the valve spring compressor tool part# 670315A on a rocker arm stud using therocker arm bearing and locking nut (diag.66).

f. Install the new o-rings (white o-ring on theexhaust guide) followed by valve springcaps, valve springs with the dampening coilstoward the head, (diag. 64) and valve spring

retainers with the larger opening away fromthe engine.


83/94

"O" RING OR GASKET

FEELERGAUGE

PUSH RODGUIDE

TABS UP

VALVE STEM

LOCKING / ADJUSTING NUTCROWN DOWN

OHH / OVRM

OVM / OHM / OVXL

OHV 11-13 and OHV 110-135 / OHSK80-130

ROCKER ARMSTUD


84/94

OHV135 - 175


85/94


86/94


87/94


88/94


89/94


90/94


91/94


92/94

TOOL KIT 670195E

Kit contains tools for 2- and 4-cycle engines.

Includes all items on this page but items may be purchased separately.


93/94


94/94

B.

C.A.

D.

Documents

Tecumseh Overhead Valve Manual