4-CYCLE OVERHEAD VALVE ENGINES

1 This manual covers engine models:OHH50 - 65, OHHSK50 - 130, OHV11 - OHV17, OVM120,OVRM40-675, OVRM120, OVXL/C120, OVXL120, illustrated Tecumseh 2-Cycle Engine, 4-CYCLE Engine andTransmission manuals; booklets; and wall charts are availablethrough complete listing write or callCONTAINS SEARS CRAFTSMAN CROSS REFERENCE4-CYCLEOVERHEADVALVEENGINEST E C H N I C I A N ' S H A N D B O O KTECUMSEHiCONTENTSC Tecumseh Products Company 1998 PageCHAPTER 1 GENERAL OF MODEL CHANGE CHANGE PROCEDURE ..3 TUNE-UP THE FUEL CYLINDER BORE ..4 CHAPTER 2 AIR INFORMATION .. OR FILTER ELEMENT OR -TYPE FILTER 3 CARBURETORS AND FUEL INFORMATION .. FUEL STYLE VISUAL I III & SERIES IV VI MODEL PRE-SETS AND AND ADJUSTMENTS (TECUMSEH AND WALBRO CARBURETORS)..13 FINAL DISASSEMBLY FUEL ADJUSTING AND AND HIGH SPEED MIXTURE ADJUSTING SCREW.

2 16 FUEL BOWL RETAINING BOWL, FLOAT, NEEDLE AND PROCEDURE ..18 WELCH SHAFT AND SHAFT AND INLET AND LOW SPEED ADJUSTING SCREW, MAIN NOZZLE ..19 INLET NEEDLE AND BOWL AND BOWL NUT ..21 IMPULSE FUEL 4 GOVERNORS AND INFORMATION ..22 ENGINE GEAR AND SHAFT GEAR OR SHAFT REPLACEMENT, UPSET STYLE GOVERNOR SHAFT REPLACEMENT, RETAINING RING CONTROLS AND TO REMOTE , OVXL, OHV VERTICAL SPEED 11-17 HORIZONTAL SPEED 5 RECOIL INFORMATION .. RETAINER REWIND STARTER (OHH, OVRM, OHM, OHSK, OVM, OVXL, OHV 11-13), AND STAMPED STEEL REWIND STARTER WITH PLASTIC SPRING STYLE STARTER (OHV -17).. 6 ELECTRICAL INFORMATION .. CIRCUIT AND ELECTRIC ALTERNATING CURRENT TO DIRECT WAVE RECTIFIER SINGLE WAVE RECTIFIER BRIDGE ELECTRICAL STARTER CIRCUIT FLOW ELECTRICAL CHARGING CIRCUIT FLOW MILLIAMP CHARGING WATT LIGHTING WATT AMP , 35 WATT AMP DC ALTERNATOR SYSTEM - DIODE IN HARNESS AMP ALTERNATOR SYSTEM REGULATOR-RECTIFIER UNDER BLOWER AMP 5 AMP OVM/.

3 44 MODELS OHV - 17 (3/5 AMP SPLIT)..44 MODELS OVM/ (RED BETWEEN ENGINE AND DIODE) ..44 MODELS OHV - 17 (RED BETWEEN ENGINE AND DIODE) ..457 AMP ALTERNATOR SYSTEM REGULATOR-RECTIFIER UNDER ENGINE AMP AMP ALTERNATOR SYSTEM WITH EXTERNAL REGULATORS ..46 FUEL SHUT-DOWN OIL SHUTDOWN OIL PRESSURE SENSOR ..47 LOW OIL STARTER VOLT OR 120 VOLT ELECTRIC STARTERS ..48 INSPECTION AND CARD 7 FLYWHEEL BRAKE INFORMATION .. BRACKET GROUNDOUT INTERLOCK CABLE ..52 BRAKE BRACKET 8 INFORMATION .. STATE IGNITION SYSTEM (CDI).. CYCLE IGNITION PLUG CAUSING FREQUENT SPARK PLUG TIMING 9 INTERNAL ENGINE AND INFORMATION .. ENGINE THEORY ..58 LUBRICATION SYSTEMS .. OPERATION PROBLEMS ..61 ENGINE OPERATION PROBLEMS .. OR RUNS VIBRATES PASSING OIL ..64 EXCESSIVE OIL HEAD AND VALVE TRAIN , SPRINGS, AND PUSH , RINGS, AND CONNECTING RING AND GUIDE REMOVAL (OVM, OHM, OHSK110 & 120, OVXL ONLY).

4 73 VALVE GUIDE INSTALLATION (OVM, OHM, OHSK110 & 120, OVXL ONLY)..73 CRANKCASE MOUNTED MOUNTED COVER, OIL SEAL, AND BEARING COVER ..75 OIL SEAL BEARING BEARING SIZE ASSEMBLY ..76 CHAPTER SPECIFICATIONS AND SEARS CRAFTSMAN VALVE SEARS CRAFTSMAN CROSS VALVE TORQUE VALVE TORQUE 11 EDUCATIONAL MATERIALS AND 1994 by Tecumseh Products CompanyAll rights reserved. No part of this book may be reproduced or transmitted, in any form or by anymeans, electronic or mechanical, including photocopying, recording or by any information storageand retrieval system, without permission in writing from Tecumseh Products Company TrainingDepartment 1 GENERAL INFORMATIONENGINE IDENTIFICATIONT ecumseh engine model, specification, and serialnumbers or date of manufacture ( ) are stampedinto the blower housing, or located on a decal on theengine in locations as illustrated (diag.)

5 1 & 2). Theengine identification decal also provides the applicablewarranty code and oil recommendations (diag. 2).Interpretation of Model NumberThe letter designations in a model number indicatethe basic type of - OVERHEAD VALVE HorizontalOHM - OVERHEAD VALVE HorizontalMediumFrameOHSK - OVERHEAD VALVE Horizontal Snow KingOVM - OVERHEAD VALVE Vertical Medium FrameOVRM - OVERHEAD VALVE Vertical Rotary MowerOVXL - OVERHEAD VALVE Vertical Medium FrameExtra LifeOHV - OVERHEAD VALVE VerticalThe number designations following the letters indicatethe basic engine number following the model number is thespecification number. The last three numbers of thespecification number indicate a variation to the basicengine serial number or indicates the productiondate of the model OHV16-204207A, serial 5215C as anexample, interpretation is as follows:OHV16-204207A is the model and VALVE Vertical16 Indicates the basic engine the specification number used forproperly identifying the parts of the serial number or (Date ofManufacture)5is the last digit in the year ofmanufacture (1995).

6 215indicates the calendar day of that year(215th day or August 3, 1995).Crepresents the line and shift on whichthe engine was built at the ENGINES that meet the California AirResource Board ( ) or the EnvironmentalProtection Agency ( ) standards will includeadditional required engine information on the : To maintain best possible emissionperformance, use only Genuine Tecumseh MODELNUMBERTHIS ENGINE MEETS 1995-1998 CALIF. EMISSION REGULATIONS FORULGE ENGINES AS APPLICABLEFUEL: REGULAR UNLEADED OIL : USE SAE 30 OHV 125 203000A (D)RTP358 UIG2RA358cc3057 DSHORT BLOCKSNew short blocks are identified by a tag marked (Short Block Horizontal) or (Short BlockVertical). Original model identification numbers of anengine should always be transferred to a new shortblock for correct parts identification (diag. 3).THIS SYMBOL POINTS OUT IMPORTANTSAFETY INSTRUCTIONS WHICH IF NOTFOLLOWED COULD ENDANGER THEPERSONAL SAFETY OF YOURSELF ANDOTHERS.

7 FOLLOW ALL OR SBH IDENTIFICATION NUMBER3 FUELST ecumseh Products Company strongly recommends the use of fresh, clean, unleaded regular gasoline in allTecumseh ENGINES . Unleaded gasoline burns cleaner, extends engine life, and promotes good starting byreducing the build up of combustion chamber deposits. Unleaded regular, unleaded premium or reformulatedgasoline containing no more than 10% Ethanol, or 15% MTBE, or 15% ETBE may also be fuel is generally not available in the United States and should not be used if any of the above optionsare use gasoline, fuel conditioners, additives or stabilizers containing methanol, white gas, or fuel blendswhich exceed the limits specified above for Ethanol, MTBE, or ETBE because engine/fuel system damagecould of which of the approved fuels are used, fuel quality is critical to engine performance.

8 Fuel shouldnot be stored in an engine or container more than 30 days prior to use. This time may be extended with theuse of a fuel stabilizer like TECUMSEH'S, part number "STORAGE" instructions in the Technician's Manual, Operators Manual, or Bulletin OILTECUMSEH FOUR CYCLE ENGINES REQUIRE THE USE OF A CLEAN, HIGH QUALITY DETERGENTOIL. Be sure original container is marked: service "SF" thru "SJ" or "CD".TECUMSEH RECOMMENDS USING ONE OF THE FOLLOWING FOUR CYCLE OILS THAT ARE SPECIALLYFORMULATED TO TECUMSEH NOT USE SAE10W40 SUMMER (Above 320 F) (0oC) USE SAE30 OIL. PART #730225 Use SAE30 oil in high temperature, high load applications. Using multigrade oil may increase oil WINTER (Below 320F) (0oC) USE SAE5W30 OIL. PART #730226(SAE 10W is an acceptable substitute.)(BELOW 00F (-18oC) ONLY): SAE 0W30 is an acceptable : For severe, prolonged winter operation of HH120 model, SAE10W oil is ModelOz.

9 ,OHSK 50-7021 630 OVRM 40 - 630 OVRM105 & 12021 630 OHSK80 - 10026 720 OHM, OHSK 110* - 13032 960 OVM 120, OVXL 120, 12532 960 OHV 11 - 13 without oil filter32 960 OHV 11 - 13 with filter391170 OHV - 17 without oil filter551650 OHV -17 2 1/4" filter (part # 36563) 621860 OHV -17 2 5/8" filter (part # 36262) 641920* NOTE: Model OHSK110 with a spec. of 221000 and up, have a capacity of 26 oz. (720 ml.)2 SHORT BLOCK IDENTIFICATION TAGSERIAL NUMBERSBV- 564 ASER 51073 Oil Change Intervals: Change the oil after the first two (2) hours of operation and every 25 hours thereafter(OHH & OHSK50-130, every 50 hours), or more often if operated under dusty or dirty the engine is run less than 25 hours per year, change the oil at least once per : The oil filter (if equipped) requires changing every 100 hours or more often if operated under dusty ordirty Check: Check the oil each time the equipment is used or every five (5) hours of operation.

10 Position theequipment so the engine is level when checking the : Remove the spark plug wire before doing any service work on the Change Procedure: Locate the oil drain plug. On some units this plug is located below the deckthrough the bottom of the mounting flange. Other units drain at the base of the engine above the deck orframe. On some rotary mower applications, where access to the drain plug is restricted by the equipment, itmay be necessary to drain the oil by tipping the mower in a position that would allow the oil to drain out of thefill units that the drain plug is accessible, remove the plug and allow the oil to drain into a proper make sure that drain oil is disposed of properly. Contact your local governing authorities to finda waste oil disposal the oil is drained, reinstall the drain plug and fill the engine with new oil to the proper PROCEDURE:NOTE: Today's fuels can cause many problems in an ENGINES performance due to the fuels quality and shortshelf life.