Wacker Neuson WM 90 Repair Manual
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Wacker Neuson WM 90 Repair Manual

Wacker Neuson WM 90 Repair Manual

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REPAIR MANUAL
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0160157en
0207
Engine
WM 90
002

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Summary of Contents for Wacker Neuson WM 90

  • Page 1 0160157en 0207 Engine WM 90 REPAIR MANUAL...
  • Page 3 WM 90 Repair Foreword Operating / Parts Information You must be familiar with the operation of this machine before you attempt to troubleshoot or repair it. Basic operating and maintenance procedures are described in the Operator’s Manual supplied with the machine.
  • Page 4 Foreword WM 90 Repair CALIFORNIA Proposition 65 Warning: Engine exhaust, some of its constituents, and certain vehicle components, contain or emit chemicals known to the State of WARNING California to cause cancer and birth defects or other reproductive harm. Laws Pertaining to Spark Arresters...

  • Page 5: Table Of Contents

    WM 90 Repair Table of Contents Emission Control System Information Safety Information Operating Safety ................14 Operator Safety while using Internal Combustion Engines ....15 Service Safety ..................16 Label Locations .................. 17 Safety Labels ..................18 Operating Labels ................21 Technical Data Specifications ..................
  • Page 6 Table of Contents WM 90 Repair Dissassembly/Reassembly General Information Tools ....................40 Ordering Parts ..................40 Reference Numbers ( ) ................40 Weight Block ..................40 Disassembly Procedures Removing Engine from Rammer ............41 Draining Oil ..................43 Removing Recoil Starter and Blower Housing ........44 Removing Muffler ................45 Removing Governor Lever, Carburetor, Speed Control Lever ....46...
  • Page 7 WM 90 Repair Table of Contents 8.16 Adjusting Governor System ..............67 8.17 Installing Muffler ................. 67 8.18 Installing Blower Housing and Recoil Starter ........68 8.19 Re-installing Engine ................69 8.20 Break-in Operation ................71 Sub Systems Magneto ..................... 72 Engine Basic Electric Theory .............

  • Page 8: Emission Control System Information

    Emission Control System Information Emission Control System Information Source of Emissions The combustion process produces carbon monoxide, oxides of nitrogen, and hydrocarbons. Control of hydrocarbons and oxides of nitrogen is very important because, under certain conditions, they react to form photochemical smog when subjected to sunlight. Carbon monoxide does not react in the same way, but it is toxic.
  • Page 9 Emission Control System Information Replacement Parts The emission control systems on your Wacker engine were designed, built, and certified to conform with EPA and California emissions regulations. We recommend the use of genuine Wacker parts whenever you have maintenance done. These original-design replacement parts are manufactured to the same standards as the original parts, so you can be confident of their performance.
  • Page 10 Emission Control System Information METHANOL - (methyl or wood alcohol) 5% by volume. You may use gasoline containing up to 5% methanol by volume, as long as it contains cosolvents and corrosion inhibitors to protect the fuel system. Gasoline containing more than 5% methanol by volume may cause starting and/or performance problems.
  • Page 11 Emission Control System Information (i) Intake manifold, if applicable. (ii) Air filter. (3) Ignition System (i) Spark plugs. (ii) Magneto or electronic ignition system. (iii) Spark advance/retard system, if applicable. (4) Exhaust manifold, if applicable (5) Miscellaneous Items Used in Above Systems (i) Electronic controls, if applicable.
  • Page 12 Emission Control System Information You are responsible for presenting your engine to the nearest service dealer authorized by Wacker when a problem exists. If you have any questions regarding your warranty rights and responsibilities, you should contact the WACKER CORPORATION Product Support Department (U.S.A.

  • Page 13: Safety Information

    WM 90 Repair Safety Information Safety Information This manual contains DANGER, WARNING, CAUTION, NOTICE and NOTE callouts which must be followed to reduce the possibility of personal injury, damage to the equipment, or improper service. This is the safety alert symbol. It is used to alert you to potential personal injury hazards.

  • Page 14: Operating Safety

    Safety Information WM 90 Repair Operating Safety Familiarity and proper training are required for the safe operation of machine. Machines operated improperly or by untrained personnel can be dangerous. Read the operating instructions contained in both WARNING this manual and the engine manual and familiarize yourself with the location and proper use of all controls.

  • Page 15: Operator Safety While Using Internal Combustion Engines

    WM 90 Repair Safety Information 2.1.18 ALWAYS guide the rammer in such a way that the operator is not squeezed between the rammer and solid objects. Special care is required when working on uneven ground or when compacting coarse material. Make sure to stand firmly when operating the machine under such conditions.

  • Page 16: Service Safety

    Safety Information WM 90 Repair Service Safety Poorly maintained machines can become a safety hazard! In order for the machine to operate safely and properly over a long period of time, periodic maintenance and occasional repairs are necessary. WARNING 2.3.1 DO NOT attempt to clean or service the machine while it is running.

  • Page 17: Label Locations

    WM 90 Repair Safety Information Label Locations wc_si000143gb.fm...

  • Page 18: Safety Labels

    Safety Information WM 90 Repair Safety Labels Wacker machines use international pictorial labels where needed. These labels are described below: Label Meaning This molded-in label contains important safety and operating information. If it becomes illegi- ble, the cover must be replaced. Refer to the Parts Book for ordering information.
  • Page 19 WM 90 Repair Safety Information Label Meaning CAUTION! Use only clean, filtered gasoline fuel. WARNING! Hot surface! WARNING! Serious injury if struck by compressed spring or cover. If the spring system cover is removed improperly, the springs can eject. Guaranteed sound power level in dB(A).
  • Page 20 Safety Information WM 90 Repair Label Meaning A nameplate listing the model number, item number, revision number, and serial number is attached to each unit. Please record the infor- mation found on this plate so it will be available should the nameplate become lost or dam- aged.

  • Page 21: Operating Labels

    WM 90 Repair Safety Information Operating Labels Wacker machines use international pictorial labels where needed. These labels are described below: Label Meaning Turn the engine switch to the ON position. Close the choke. Pull the rewind starter. Open the choke.
  • Page 22 Safety Information WM 90 Repair Label Meaning Throttle control lever: Turtle = Idle or Slow Rabbit = Full or Fast Fuel valve: Closed Open Engine stop button: Press to stop engine. Choke: 0 = Open l = Closed wc_si000143gb.fm...

  • Page 23: Technical Data

    WM 90 Technical Data Technical Data Specifications Engine Model WM 90 Engine Engine Speed - full 4200 ± 100 Engine Speed - idle 2000 ± 100 Clutch Engagement 2500 ± 100 Spark Plug type NGK BM4A or BMR4A Electrode Gap mm (in) 0.6–0.7 (0.023–0.028)

  • Page 24: Performance

    Technical Data WM 90 Performance Description Description Maximum torque Recommended horsepower range Continuous rated horsepower Output Maximum horsepower Torque wc_td000143gb.fm...

  • Page 25: Theory Of Operation

    WM 90 Theory of Operation Theory of Operation Application Rammers are designed to compact loose soils and gravel to prevent settling and to provide a firm, solid base for the placement of footings, concrete slabs, foundations, and other structures. Recommended Fuel This engine is certified to operate on automotive unleaded gasoline.

  • Page 26: To Start

    Theory of Operation WM 90 To Start See Graphic: wc_gr001454 Note: After transporting the rammer horizontally, upright the rammer and allow the oil to drain back through the engine. It may take up to 2 minutes for the oil level to recover.

  • Page 27: To Stop

    WM 90 Theory of Operation To Stop See Graphic: wc_gr001454 4.5.1 Place throttle in the idle position (c2). 4.5.2 Turn engine switch to "OFF" (d). 4.5.3 Close fuel valve (e). Component Descriptions Component Illustration Component Description The cylinder/crankcase is a single piece alumi- num die-casting.
  • Page 28 Theory of Operation WM 90 Component Illustration Component Description The crankshaft is forged carbon steel, and the crank pin is induction-hardened. The output end of the shaft has a crankshaft gear that is pressed into position. wc_gr001872 The connecting rod is an aluminum alloy die- casting and its large and small ends function as bearings.
  • Page 29 WM 90 Theory of Operation Component Illustration Component Description The intake valve is located on the flywheel side of the cylinder head. Hard alloy valve seats are molded in the cylinder head and satellite is fused to the exhaust valve face. The cylinder baffle leads cooling air to the exhaust valve area for optimum cooling.
  • Page 30 Theory of Operation WM 90 Component Illustration Component Description The large fins (a) on the flywheel provide suffi- cient cooling air capacity for the inlet and exhaust area and cylinder. The cylinder baffle directs the cooling air flow efficiently. wc_gr001949...
  • Page 31 WM 90 Theory of Operation Component Illustration Component Description WM 90 engines use a diaphragm-type carbu- retor. wc_gr001881 The air cleaner is a heavy-duty three-stage type with cyclonic precleaner. wc_gr002032 An automatic decompression mechanism (a), that opens the exhaust valve before the piston reaches maximum compression, is assembled on the camshaft for easy starting.

  • Page 32: Cross Section Across Shaft

    Theory of Operation WM 90 Cross Section Across Shaft wc_gr001884 wc_tx000388gb.fm...

  • Page 33: Cross Section Across Shaft Components

    WM 90 Theory of Operation Cross Section Across Shaft Components See Graphic: wc_gr001884 Description Description Cylinder head Main bearing cover Piston pin PTO shaft Ignition coil Piston ring Blower housing Piston Recoil starter Muffler Flywheel Exhaust valve Crankcase Intake valve Flange adapter wc_tx000388gb.fm...

  • Page 34: Cross Section Along Shaft

    Theory of Operation WM 90 Cross Section Along Shaft wc_tx000388gb.fm...

  • Page 35: Cross Section Along Shaft Components

    WM 90 Theory of Operation 4.10 Cross Section Along Shaft Components See Graphic: wc_gr001885 Description Description Push rod Stiffener Carburetor Plug Air cleaner Oil gauge Tappet Connecting rod Camshaft Spark plug Governor lever Rocker arm Speed control lever Rocker cover Crankshaft wc_tx000388gb.fm...

  • Page 36: Maintenance

    Maintenance WM 90 Repair Maintenance Periodic Maintenance Schedule Before Every Every Every Every each 500 hours or hours hours hours yearly Check for fluid leaks. Check engine oil. Check fuel level. Check for loose hardware. Clean debris from engine. Change engine oil*.

  • Page 37: Servicing Air Cleaner

    WM 90 Repair Maintenance Servicing Air Cleaner See Graphic: wc_gr001306 NEVER use gasoline or other types of low flash point solvents for cleaning the air filter. A fire or explosion could result. WARNING NOTICE: NEVER run the engine without the main paper air filter (b).

  • Page 38: Servicing Fuel Filter And Fuel Tank

    Maintenance WM 90 Repair Servicing Fuel Filter and Fuel Tank See Graphic: wc_gr002017 5.3.1 Drain fuel tank completely. 5.3.2 Remove fuel line from fuel flow valve (a). 5.3.3 Unscrew fuel filter assembly (b) from tank. 5.3.4 Clean filter with parts cleaning solvent.

  • Page 39: Long-Term Storage

    WM 90 Repair Maintenance Long-Term Storage 5.4.1 Drain the fuel from the tank. 5.4.2 Start the engine and run it until remaining fuel is used. 5.4.3 Remove the spark plug. Pour approximately 30 ml (1 oz.) of clean SAE 10W30 engine oil into the cylinder through the spark plug opening.

  • Page 40: Dissassembly/Reassembly General Information

    Dissassembly/Reassembly General Information WM 90 Repair Dissassembly/Reassembly General Information Tools Because all possible problems encountered while repairing the machine cannot be anticipated, it is up to the mechanic to use common sense and good judgement in tool selection. The use of any special tools is recommended only for those operations where the use of conventional tools proves inadequate.

  • Page 41: Disassembly Procedures

    WM 90 Repair Disassembly Procedures Disassembly Procedures Removing Engine from Rammer See Graphic: wc_gr001954, wc_gr003661, wc_gr001956, and wc_gr001957 7.1.1 Disconnect the spark plug cap (a) from the spark plug. 7.1.2 Disconnect the fuel line (b) from the carburetor and plug the line.
  • Page 42 Disassembly Procedures WM 90 Repair wc_gr003661 wc_gr001954 wc_tx000389gb.fm...

  • Page 43: Draining Oil

    WM 90 Repair Disassembly Procedures Draining Oil See Graphic: wc_gr001886 Note: In the interests of environmental protection, place plastic sheeting and a container under the machine to collect the liquid which drains off. Dispose of this liquid properly. 7.2.1 Remove the drain plug (a) and gasket (b).

  • Page 44: Removing Recoil Starter And Blower Housing

    Disassembly Procedures WM 90 Repair Removing Recoil Starter and Blower Housing See Graphic: wc_gr003650 7.3.1 Remove the bolts (a) and remove the recoil starter (b) from the housing. 7.3.2 Remove the flange bolts (f), cap screw (g), and remove the blower housing (h).

  • Page 45: Removing Muffler

    WM 90 Repair Disassembly Procedures Removing Muffler See Graphic: wc_gr001888 7.4.1 Remove the flange nuts (a). 7.4.2 Remove the flange bolts (b). 7.4.3 Remove the bolts and washers (c) and remove the muffler (d) and the gasket (e). wc_tx000389gb.fm...

  • Page 46: Removing Governor Lever, Carburetor, Speed Control Lever

    Disassembly Procedures WM 90 Repair Removing Governor Lever, Carburetor, Speed Control Lever See Graphic: wc_gr001890 7.5.1 Mark the hole in which the governor spring (a) is attached and remove the spring. 7.5.2 Loosen the M6 bolt (b) and remove the governor lever (c).

  • Page 47: Removing Ignition Coil, Flywheel, And Spark Plug

    WM 90 Repair Disassembly Procedures Removing Ignition Coil, Flywheel, and Spark Plug See Graphic: wc_gr001891 7.6.1 Remove the spark plug (a). 7.6.2 Remove the two M6 x 25 bolts (b) and remove the ignition coil (c). 7.6.3 Remove the M12 nut and washer (d), four M6 bolts (e), and remove the starter pulley (f) and flywheel (g).

  • Page 48: Removing Rocker Cover And Cylinder Head

    Disassembly Procedures WM 90 Repair Removing Rocker Cover and Cylinder Head See Graphic: wc_gr001892 7.7.1 Remove the four M6 x 60 bolts (a) and remove the rocker cover (b) and gasket (c). 7.7.2 Remove the breather (d), gaskets (e), and spacer (f).

  • Page 49: Removing Bearing Cover

    WM 90 Repair Disassembly Procedures Removing Bearing Cover See Graphic: wc_gr001893 7.8.1 Remove the nine M6 x 30 bolts and washers (a) and remove the main bearing cover (b). Note: If necessary, use a rubber mallet (c) and tap the cover to loosen it from the crankcase.

  • Page 50: Removing Camshaft And Tappets

    Disassembly Procedures WM 90 Repair Removing Camshaft and Tappets See Graphic: wc_gr001894 7.9.1 Lay crankcase on the flywheel side and push the tappets (a) into the crankcase and remove the camshaft (b). wc_gr001894 wc_tx000389gb.fm...

  • Page 51: Removing Connecting Rod And Piston

    WM 90 Repair Disassembly Procedures 7.10 Removing Connecting Rod and Piston See Graphic: wc_gr001895 7.10.1 Remove connecting rod bolts (a) and connecting rod cap (b). 7.10.2 Turn crankshaft until piston (c) comes to top dead center, push out connecting rod (d) and piston assembly through top of cylinder.

  • Page 52: Removing Crankshaft

    Disassembly Procedures WM 90 Repair 7.11 Removing Crankshaft See Graphic: wc_gr001896 7.11.1 To remove the crankshaft (a), tap lightly on flywheel end of the crankshaft with a rubber mallet (b). wc_gr001896 wc_tx000389gb.fm...

  • Page 53: Removing Intake And Exhaust Valves

    WM 90 Repair Disassembly Procedures 7.12 Removing Intake and Exhaust Valves See Graphic: wc_gr001897 Note: The procedure is the same for removing each valve. 7.12.1 Remove pivot bolt (a), rocker arm (b), and nut (c). 7.12.1 Press down the spring retainer (d), take out the collet (e), and then remove spring retainer and valve spring (f).

  • Page 54: Reassembly Procedures

    Reassembly Procedures WM 90 Repair Reassembly Procedures Notes on Reassembly Observe the following prior to/during reassembly of the engine: • Clean each part carefully, taking special care with the piston, cylinder, crankshaft, connecting rod, and bearings. • Scrape off any carbon deposits on the cylinder head and the piston head.

  • Page 55: Reassembling Piston

    WM 90 Repair Reassembly Procedures Reassembling Piston See Graphic: wc_gr001874, wc_gr001899 and wc_gr001900 Install each piston ring in the correct groove of the piston by widening it enough to slide it over the piston. Note: When installing the piston rings, make sure not to twist the rings too much as they may become damaged.

  • Page 56: Reassembling Piston And Connecting Rod

    Reassembly Procedures WM 90 Repair Reassembling Piston and Connecting Rod See Graphic: wc_gr001901 8.4.1 Install the piston (a) onto the connecting rod (b) using the piston pin (c) and two clips (d). wc_gr001901 wc_tx000389gb.fm...

  • Page 57: Installing Piston

    WM 90 Repair Reassembly Procedures Installing Piston See Graphic: wc_001902, wc_gr001903, and wc_gr001904 8.5.1 Position the piston rings so that the gaps in the rings are at 90° intervals from each other (a = top ring, b = second ring, c = oil ring).

  • Page 58: Installing Tappets And Camshaft

    Reassembly Procedures WM 90 Repair Installing Tappets and Camshaft See Graphic: wc_gr001905 8.6.1 Oil the tappets (a) and install them. Push them in fully to avoid damage during camshaft (b) installation. 8.6.2 Remove spacer (c) to allow viewing of timing mark.

  • Page 59: Adjusting Crankshaft End Play

    WM 90 Repair Reassembly Procedures Adjusting Crankshaft End Play See Graphic: wc_gr001906 Adjust the end play to 0.2 mm (0.008 in.) using the proper spacer. Determine the proper spacer in the following manner: 8.7.1 Measure the height “A”. Distance from main bearing cover mating surface (a) to the inner race of the ball bearing (b).

  • Page 60: Installing Main Bearing Cover

    Reassembly Procedures WM 90 Repair Installing Main Bearing Cover See Graphic: wc_gr001907 8.8.1 Lubricate the oil seal and bearing surfaces with engine oil. 8.8.2 Coat the mating surfaces of the main bearing cover (a) and crankcase ® (b) with Loctite 515 Gasket Eliminator or equivalent.

  • Page 61: Cylinder Head

    WM 90 Repair Reassembly Procedures Cylinder Head 8.9.1 Clean carbon and gum deposits from the valves, seats, ports, and guides. Inspect them once clean. Replace valves that are badly burned, pitted, or warped. 8.9.2 When installing valves in cylinder head, oil the valve stems and insert them into valve guide.

  • Page 62: Reassembling Rocker Arms And Push Rods

    Reassembly Procedures WM 90 Repair 8.10 Reassembling Rocker Arms and Push Rods See Graphic: wc_gr001908 8.10.1 Insert push rods (a) into crankcase. Place push rod tip into the hollow of the tappet top. NOTICE: An oil return slot is located next to the tappet boss. If you do not put the push rod in the tappet properly, the push rods will fall into the crankcase.

  • Page 63: Adjusting Valve Clearances

    WM 90 Repair Reassembly Procedures 8.11 Adjusting Valve Clearances See Graphic: wc_gr001909 and wc_gr001910 Note: Check and adjust valve clearances when engine is cold. 8.11.1 Temporarily fit the flywheel in position. 8.11.2 Position the piston at the top dead center of the compression stroke by matching the alignment mark on the flywheel (a) with the alignment mark on the crankcase (b).

  • Page 64: Installing Rocker Cover And Spark Plug

    Reassembly Procedures WM 90 Repair 8.12 Installing Rocker Cover and Spark Plug See Graphic: wc_gr001911 Note: Replace the gasket with a new one each time the rocker cover is removed. 8.12.1 Using four M6 bolts (a), secure the rocker cover (b) and gasket (c) to the cylinder head.

  • Page 65: Installing Flywheel Magneto

    WM 90 Repair Reassembly Procedures 8.13 Installing Flywheel Magneto 8.13.1 Place the Woodruff key in the keyway of the crankshaft. Thoroughly wipe off oil and grease from the tapered portion of the crankshaft and also from the flywheel center hole.

  • Page 66: Installing Governor, Speed Control System, And Carburetor

    Reassembly Procedures WM 90 Repair 8.15 Installing Governor, Speed Control System, and Carburetor See Graphic: wc_gr001890 8.15.1 Install governor lever (a) to governor shaft, then tighten the locking bolt (b) temporarily. 8.15.2 Install baseplate (t) to crankcase using two M6 x 8 flange bolts (s).

  • Page 67: Adjusting Governor System

    WM 90 Repair Reassembly Procedures 8.16 Adjusting Governor System See Graphic: wc_gr001914 8.16.1 Turn the speed control lever (a) all the way toward the high speed position and secure it by tightening the self-locking screw. 8.16.2 Check that the governor lever (b) is pulled by the governor spring (c) and carburetor throttle valve is fully open.

  • Page 68: Installing Blower Housing And Recoil Starter

    Reassembly Procedures WM 90 Repair 8.18 Installing Blower Housing and Recoil Starter See Graphic: wc_gr003650 8.18.1 Install the blower housing (h) using the flange bolts (f) and cap screw (g). 8.18.2 Install the recoil starter (b) to the housing using the bolts (a).

  • Page 69: Re-Installing Engine

    WM 90 Repair Reassembly Procedures 8.19 Re-installing Engine See Graphic: wc_gr001954, wc_gr003661, wc_gr001956, and wc_gr001957 8.19.1 Position the engine so that mounting studs protrude from the adapter plate mounted to the rammer crankcase. Position heatshield and secure engine and heatshield to rammer with four nuts (j).
  • Page 70 Reassembly Procedures WM 90 Repair wc_gr003661 wc_gr001954 wc_tx000389gb.fm...

  • Page 71: Break-In Operation

    WM 90 Repair Reassembly Procedures 8.20 Break-in Operation A new engine or one that has been completely overhauled by being fitted with a new piston, rings, valves, and connecting rod should be thoroughly run-in before being put into service. Good bearing surfaces and running clearances between the various parts can only be established by operating the engine under reduced speed and loads for a short period of time.

  • Page 72: Sub Systems

    WM 90 Repair Sub Systems Magneto The ignition system of the WM 90 is a breakerless flywheel magneto with an automatic advancing system. This system has no breaker points and thus is free from the starting and running problems associated with dirty, burnt, or corroded breaker points.

  • Page 73: Electrical Components

    WM 90 Repair Sub Systems Electrical Components See Graphic: wc_gr001916 Description Description Low-speed ignition timing circuit Spark plug Signal transistor A Ignition timing (BTDC) Automatic advancing control circuit Engine revolution (rpm) Signal transistor B Step advancing Resistor Stop switch Power transistor...

  • Page 74: Automatic Decompression System

    WM 90 Repair Automatic Decompression System See Graphic: wc_gr001917 WM 90 engines employ an automatic decompression system as a standard feature. This system enables easy starting of the engine, with lighter recoil pull. The automatic decompression system releases the compression of the engine by lifting up the exhaust valve at cranking speeds.

  • Page 75: Diaphragm-Type Carburetor

    WM 90 Repair Sub Systems Diaphragm-Type Carburetor See Graphic: wc_gr001919 Description Comment Engine impulse The alternating action of the positive pressure and neg- ative pressure inside the engine crankcase operates the fuel pump diaphragm. Fuel pump diaphragm The fuel pump diaphragm undulates in response to the engine impulse and as a result, it feeds the fuel through the fuel pump.
  • Page 76 Sub Systems WM 90 Repair Description Comment Metering chamber The metering chamber is the fuel storage compartment that has the function of supplying fuel to the nozzle holes and other parts. First idle hole The first idle hole is the only fuel supply hole that is available when the engine is idling.
  • Page 77 WM 90 Repair Sub Systems wc_gr001919 wc_tx000390gb.fm...

  • Page 78: Carburetor Disassembly Procedure

    Sub Systems WM 90 Repair Carburetor Disassembly Procedure See Graphic: wc_gr001920 Prior to disassembling the carburetor, wash it with an appropriate cleaning solvent. 9.6.1 Loosen the pump cover screw (14) and remove the screw and the pump cover (13). 9.6.2 Remove the pump gasket (12) and the diaphragm (11).

  • Page 79: Carburetor Inspection

    WM 90 Repair Sub Systems Carburetor Inspection See Graphic: wc_gr001920 9.7.1 Clean the carburetor and components with an appropriate solvent. 9.7.2 Check the gaskets for any deformation and/or damage. Replace any deformed or damaged gaskets. 9.7.3 Make sure that the pump diaphragm (11) is not damaged. Also make sure that the inlet valve and outlet valve are flat and not bent.

  • Page 80: Carburetor Adjustments

    Sub Systems WM 90 Repair Carburetor Adjustments See Graphic: wc_gr001920 Idling Adjustment: 9.9.1 Start the engine and adjust the idle adjust screw (15) so that the engine is running at a speed slightly lower than the speed at which the clutch engages.

  • Page 81: Recoil Starter

    WM 90 Repair Recoil Starter 10. Recoil Starter 10.1 Recoil Starter Disassembly For machines with item numbers 0009386 rev. 111 and lower; 0009340 rev. 111 and lower; 0620051 rev. 107 and lower See Graphic: wc_gr001830 Wear eye protection when working on the recoil starter.
  • Page 82 Recoil Starter WM 90 Repair See Graphic: wc_gr001831 To remove the components: 10.1.6 Grip the case (a) and loosen the set screw (b). 10.1.7 Remove, in this order: the set screw, the ratchet guide (c), the friction spring (d), and the ratchet (e).
  • Page 83 WM 90 Repair Recoil Starter Reassembly See Graphic: wc_gr001832 Re-installing the reel: 10.1.11 Apply grease (Exxon Unirex or equivalent) (a) to the surface of the case. 10.1.12 Adjust the position of the inner end of the spring reel. Reference (b): position where the inner end of the spring touches the rib of the bearing.
  • Page 84 Recoil Starter WM 90 Repair See Graphic: wc_gr001835 Tensioning the reel spring: 10.1.17 Grip the case and turn the reel 6 times counterclockwise. 10.1.18 Rotate the reel so that the rope hole (a) is aligned with the rope guide (b).

  • Page 85: Checking The Recoil Starter After Reassembly

    WM 90 Repair Recoil Starter 10.2 Checking the Recoil Starter After Reassembly For machines with item numbers 0009386 rev. 111 and lower; 0009340 rev. 111 and lower; 0620051 rev. 107 and lower Note: Carry out the following procedures to ensure proper operation of the starter assembly.

  • Page 86: Starter Assembly Exploded View

    Recoil Starter WM 90 Repair 10.3 Starter Assembly Exploded View For machines with item numbers 0009386 rev. 112 and higher; 0009340 rev. 112 and higher; 0620051 rev. 108 and higher wc_gr002880 See Graphic: wc_gr002880 Description Description Starter assembly Spring Rope...

  • Page 87: Disassembling The Starter

    WM 90 Repair Recoil Starter 10.4 Disassembling the Starter For machines with item numbers 0009386 rev. 112 and higher; 0009340 rev. 112 and higher; 0620051 rev. 108 and higher See Graphic: wc_gr002880 10.4.1 Remove the starter assembly from the fan cover and release the spring tension as described in section Replacing the Starter Rope.

  • Page 88: Assembling The Starter

    Recoil Starter WM 90 Repair Rope Check the rope length. It is 150 cm (60 in.) when new. If the rope is too short, it may bottom out when pulled and damage the starter. wc_gr002881 10.6 Assembling the Starter For machines with item numbers 0009386 rev. 112 and higher;...

  • Page 89: Replacing The Starter Rope

    WM 90 Repair Recoil Starter 10.6.4 Lightly grease the center post of the housing and install the wear plate (4) and the rope reel pulley. Rotate the rope reel pulley until the spring seats in the slot at the center of the housing (13). Install the washer (7) over the center post and seat it into the rope reel pulley.
  • Page 90 Recoil Starter WM 90 Repair wc_gr002882 wc_tx000627gb.fm...

  • Page 91: Clearance Data And Limits Table

    WM 90 Repair Clearance Data and Limits Table 11. Clearance Data and Limits Table 11.1 Term Descriptions The following table lists critical dimensions of specific parts. The “Standard” column lists the dimension of the part as new from the factory. The “Limit” column lists the maximum allowance. If the measurement exceeds the “Limit”...
  • Page 92 Clearance Data and Limits Table WM 90 Repair Item Standard Limit mm (in.) mm (in.) Piston 50.88 50.97–50.99 (2.0031) (2.0067–2.0075) Outer diameter at skirt in thrust Oversize 51.13 51.22–51.24 direction (+0.25) (2.0123) (2.0165–2.0173) Oversize 51.38 51.47–51.49 (+0.50) (2.0228 (2.0264–2.0272) wc_gr001925 Ring groove-side clearance 0.035–0.080...
  • Page 93 WM 90 Repair Clearance Data and Limits Table Item Standard Limit mm (in.) mm (in.) Clearance between piston and cylinder at skirt 0.010–0.049 0.25 (0.0004–0.0019) (0.010) wc_gr001929 Piston ring end gap 0.15–0.35 Top ring (0.006–0.014 (0.0591) 0.35–0.55 2nd ring (0.014–0.022 (0.0591)
  • Page 94 Clearance Data and Limits Table WM 90 Repair Item Standard Limit mm (in.) mm (in.) Connectng rod Large-end inner diameter 20.1 20.000–20.013 (0.7913) (0.7874–0.7879) 120˚ Clearance between large end and crank pin 0.037–0.063 (0.008) (0.0015–0.0025) wc_gr001933 Small end inner diameter 11.08...
  • Page 95 WM 90 Repair Clearance Data and Limits Table Item Standard Limit mm (in.) mm (in.) Large end side clearance 0.1–0.7 (0.04) (0.004–0.028) wc_gr001936 Crankshaft Crank pin outer diameter 19.85 19.950–19.963 (0.7815) (0.7854–0.7859) wc_gr001937 Journal outer diamete 19.988–19.997 and D (0.7869–0.7873)
  • Page 96 Clearance Data and Limits Table WM 90 Repair Item Standard Limit mm (in.) mm (in.) Journal outside diameter 9.95 9.972–9.987 (0.3917) (0.3926–0.3932) 9.95 9.972–9.987 (0.3917) (0.3926–0.3932) wc_gr001940 Intake/exhaust valves 5.35 5.440–5.455 Intake (0.2106) (0.2142–0.2148) Valve stem outer diameter 5.35 5.426–5.444 Exhaust (0.2106)
  • Page 97 WM 90 Repair Clearance Data and Limits Table Item Standard Limit mm (in.) mm (in.) Tappet Stem outside diameter 7.960–7.975 (0.3134–0.3140) wc_gr001944 Guide inside diameter 8.00–8.015 (0.3150–0.3140) wc_gr001945 Tappet guide clearance 0.025–0.055 (0.0010–0.0022) wc_gr001946 Valve seat angle (intake and exhaust)
  • Page 98 Clearance Data and Limits Table WM 90 Repair Item Standard Limit mm (in.) mm (in.) Valve spring free length 26.7 (1.05) wc_gr001947 wc_tx000391gb.fm...

  • Page 99: Troubleshooting

    WM 90 Repair Troubleshooting 12. Troubleshooting 12.1 Troubleshooting Introduction If the engine shows any sign of malfunction, the cause should be determined immediately and the appropriate countermeasures should be taken to prevent the problem from worsening. This troubleshooting section describes certain known problems, their possible causes, and appropriate action to take.
  • Page 100 Troubleshooting WM 90 Repair 12.2.2 Ignition System Problems: Check the following when experiencing a lack of spark. 12.2.2.1 Wires of the ignition coil, spark plug, or contact breaker disconnected. 12.2.2.2 Ignition coil damaged or shorted. 12.2.2.3 Spark plug wire wet or soaked with oil.
  • Page 101 WM 90 Repair Troubleshooting 12.2.5 Engine Stops: 12.2.5.1 Fuel tank empty. Water, dirt, gum, etc. in gasoline. 12.2.5.2 Vapor lock. Gasoline evaporating in the fuel lines due to overheating of the engine. 12.2.5.3 Vapor lock in the fuel lines or carburetor due to using too volatile gas blend (winter formula) in the hot season.
  • Page 102 Troubleshooting WM 90 Repair Notes wc_tx000393gb.fm...
  • Page 103 Threadlockers and Sealants Threadlockers and Sealants Threadlocking adhesives and sealants are specified throughout this manual by a notation of “S” plus a number (S#) and should be used where indicated. Threadlocking compounds normally break down at temperatures above 175°C (350°F). If a screw or bolt is hard to remove, heat it using a small propane torch to break down the sealant.
  • Page 104 Threadlockers and Sealants Threadlockers and Sealants (continued) Threadlocking adhesives and sealants are specified throughout this manual by a notation of “S” plus a number (S#) and should be used where indicated. Threadlocking compounds normally break down at temperatures above 175°C (350°F). If a screw or bolt is hard to remove, heat it using a small propane torch to break down the sealant.

  • Page 105: Torque Values

    Torque Values Torque Values Metric Fasteners (DIN) TORQUE VALUES (Based on Bolt Size and Hardness) WRENCH SIZE 10.9 12.9 Size ft.lb. ft.lb. ft.lb. Metric Inch Metric Inch 7/32 – 9/32 – 5/16 – – – – 11/16 – – – 15/16 –...
  • Page 106 Torque Values Torque Values (continued) Inch Fasteners (SAE) Size ft.lb. ft.lb. ft.lb. Metric Inch Metric Inch No.4 – 3/32 No.6 5/16 – 7/64 No.8 11/32 – 9/64 No.10 – – 5/32 – 7/16 – 3/32 5/16 – – 9/16 – 5/16 7/16 –...
  • Page 108 Wacker Construction Equipment AG · Preußenstraße 41 · D-80809 München · Tel.: +49-(0)89-3 54 02 - 0 · Fax: +49 - (0)89-3 54 02-3 90 Wacker Corporation · P.O. Box 9007 · Menomonee Falls, WI 53052-9007 · Tel. : (262) 255-0500 · Fax: (262) 255-0550 · Tel. : (800) 770-0957 Wacker Asia Pacific Operations ·...

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