MTD P61 Series Professional Shop Manual
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MTD P61 Series Professional Shop Manual

MTD P61 Series Professional Shop Manual

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For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983
Professional Shop Manual
P61/P65/P70 Series Vertical Shaft Engines
Second edition
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 inexperi-
enced individuals should seek the assistance of an experienced and trained professional. Read, understand, and follow all
instructions and use common sense when working on power equipment. This includes the contents of the product's Oper-
ators 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 2008 MTD Products Inc. All Rights Reserved
MTD Products Inc - Product Training and Education Department
FORM NUMBER - 769-03354A
08/2008
www.mymowerparts.com

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  • Page 1 Instructions, photographs and illustrations used in this publication are for reference use only and may not depict actual model and component parts. © Copyright 2008 MTD Products Inc. All Rights Reserved MTD Products Inc - Product Training and Education Department...
  • Page 2 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 www.mymowerparts.com...

  • Page 3: Table Of Contents

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Table of Contents Chapter 1: Introduction ..................1 Professional Shop Manual intent ....... . . 1 Assembly .
  • Page 4 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Charcoal canister ......... . . 36 EVAP fuel tank .
  • Page 5 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 9: Cylinder Head ................... 83 Valves ........... . 85 Chapter 10: Crankshaft, piston and Connecting Rod ........
  • Page 6 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 www.mymowerparts.com...

  • Page 7: Chapter 1: Introduction

    In many cases, both will be • In no event shall MTD or Cub Cadet be liable for used so that the manual is handy as a quick-reference for poor text interpretation, or poor execution of guide as well as a step-by-step procedure guide that the procedures described in the text.
  • Page 8 M ow e r (lo n g sh a ft/n o sh r ou d ) Ti lle r L o gs p litte r W o rl d T il le r MTD Engine Serial Numbers 1P65FH/0510271A0023 Model number Year...

  • Page 9: Maintenance

    Spark plugs and non-warrantable engine damage may result. The spark plug used in the MTD engine is a Inspection of the spark plug can provide indica- Torch model F6RTC gapped to .024”-.032” (.60- tions of the operating condition of the engine.

  • Page 10: Air Filters

    The paper pleated filters can be shaken MTD vertical shaft engines use two different air filters. or lightly tapped to free the debris from the filter. The first is a rectangular paper pleated filter with a foam pre-filter.

  • Page 11: Oil Type And Capacity

    Sealing Washer • Synthetic oil is a suitable alternative, but it does not extend service intervals. NOTE: MTD recommends the use of petroleum oil during the break in period to ensure the piston rings correctly break in. • Synthetic vs. Petroleum based oil: To simply look Figure 1.5...

  • Page 12: Fuel

    Alcohol also does not produce as much heat as gasoline when burnt. This results in less power for the engine. A 10% alcohol mix (E10) is acceptable for MTD engines. Anything higher than that will result in perfor- mance and starting issues.

  • Page 13: Fuel Filters

    To help prevent that, the valve stem and the rocker arm. The valve lash should MTD engine is equipped with a fuel filter. be checked after the first 25 hours of use and every 100 hours after that. Valve lash can be checked and...
  • Page 14 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 1: INTRODUCTION Confirm that the piston is at Top-Dead-Center on Exhaust valve lash (bottom valve) should be the compression stroke. See Figure 1.10. .005-.007” (.15 + .02mm). See Figure 1.12. Setting exhaust valve lash .006”...

  • Page 15: Exhaust System

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 1: INTRODUCTION Install the spark plug. Release the spring clamp securing the safety bail, start the engine and test run it long enough to confirm correct operation. Exhaust system The exhaust system is a frequently overlooked component of an engine.

  • Page 16: General Torque Specifications

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 1: INTRODUCTION General torque specifications size size Grade in-lbs ft-lbs Nm 1.2 10.5 21.7 36.6 in-lbs ft-lbs Nm 1.7 13.6 27.1 47.5 in-lbs ft-lbs Nm 2.9 24.4 47.5 82.7 10.9 in-lbs ft-lbs Nm 4.1...

  • Page 17: Chapter 2: Basic Troubleshooting

    NOTE: The steps and the order of the steps that follow are a suggested approach to trouble- There are tools that the technician can use in order to shooting the MTD engine. define the problem, such as: Interview the customer.

  • Page 18: Identify Factors That Could Cause The Problem

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 2: Basic Troubleshooting Cleanliness of the equipment will indi- Identify factors that could cause the problem cate the level of care the equipment This is the second step in the troubleshooting process. has received.
  • Page 19 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 2: Basic Troubleshooting IV. Bent crankshaft (unrepairable) Starts, runs poorly V. Internal binding, crankshaft, connect- 3a. Starts, then dies ing rod or piston (unrepairable) Run the engine with a spark tester in- Crankshaft turns, no start.
  • Page 20 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 2: Basic Troubleshooting V. Low compression float valve stuck or metering / emulsion issues with the carbure- a. Check valve lash tor. b. Check compression b. White smoke, usually heavy c.
  • Page 21 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 2: Basic Troubleshooting exceeding 10% will make the ing into play as the engine RPMs cross the activation threshold. engine run artificially lean. This will have no ill effects on c.

  • Page 22: Repairing The Problem

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 2: Basic Troubleshooting Repairing the problem Prime test The third step in the troubleshooting process is to To perform a prime test: repair the problem. This step consists of: Prime the engine through the carburetor throat Form a diagnosis by using all of the information using a squirt bottle, filled with clean fresh gaso- gathered from the troubleshooting that was per-...

  • Page 23: Leak-Down Test

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 2: Basic Troubleshooting Leak-down test Connect tester to compressed air. A leak-down test is the preferred method to test the Adjust the regulator knob until the needle on the engine’s ability to compress the charge. It will also gauge is in the yellow or set area of the gauge.

  • Page 24: Compression Test

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 2: Basic Troubleshooting Interpreting compression readings. Compression test To perform a compression test: Table 2: NOTE: Compression should be in the range of 45-95 PSI (3.1-6.5 Bar). Readings in Possible causes •...

  • Page 25: Pcv Testing

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 2: Basic Troubleshooting PCV testing When functioning properly, the PCV valve (Posi- tive Crankcase Ventilation) works with the inher- The PCV valve is located under the flywheel and ent pumping action of the piston in the bore to allows the crankcase pressure to escape.
  • Page 26 (compres- Gasket sion, leak-down, and case pressure) is not per- formed. Baffle Experimentation by MTD’s Training and Educa- Disc tion Department has revealed the following char- acteristics of MTD engines: • A leaky PCV system will not build-up substantial case pressure.
  • Page 27 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 2: Basic Troubleshooting The port to the PCV hose is near the top of the • This 2-3 PSI (.14-.20 Bar) build-up will dissipate chamber. The oil tends to settle out of suspen- through the drain-back port over the course of 5- sion, leaving mostly air to exit the chamber 10 seconds.
  • Page 28 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 2: Basic Troubleshooting www.mymowerparts.com...

  • Page 29: Chapter 3: Air Intake And Filter

    Swing open the filter cover. See Figure 3.2. MTD vertical shaft engines use two different air filters. The first is a rectangular paper pleated filter with a foam pre-filter. The second is an oval foam filter.

  • Page 30: Foam Air Filter

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 3: Air Intake and filter Remove the screw that holds the air filter hous- Foam air filter ing to the control bracket. See Figure 3.3. Press in the tab on the air filter cover. See Figure 3.5.
  • Page 31 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 3: Air Intake and filter Air filter housing Disconnect the primer line. See Figure 3.8. To remove the air filter housing: Lift away the filter housing. Remove the air filter by following the steps The primer can be removed from the air filter described above.

  • Page 32: Carburetor Insulator

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 3: Air Intake and filter 2c. After the second stud is removed, the carbu- Carburetor Insulator retor can be maneuvered to disconnect the CAUTION: When working around the fuel sys- linkages.
  • Page 33 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 3: Air Intake and filter 2e. Pivot the carburetor to disengage the Z-fit- The insulator is sandwiched between two gas- ting on the end of the choke rod. kets which are located between the carburetor See Figure 3.14.
  • Page 34 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 3: Air Intake and filter • The gasket with the “D” shaped opening goes between the insulator and the cylinder head, matching the shape of the gasket to the shape of the intake port.

  • Page 35: Chapter 4: The Fuel System And Governor

    This results in less power for the engine. NOTE: Fuel is the maintenance item most often A 10% ethanol (E10) mix is acceptable for MTD overlooked by consumers. A lot of fuel systems engines. Anything higher than that will result in perfor- problems are caused by bad gas or too much mance issues.

  • Page 36: Fuel Tank Vent

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 4: The Fuel System and Governor Generally these kits involve mixing a measured amount To test the cap vent of water and gas together and seeing were the bound- A hand-pumped vacuum / pressure tester may ary layer is.

  • Page 37: The Fuel Filter

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 4: The Fuel System and Governor The fuel filter: Inspect the fuel lines: The fuel filter is located in the fuel tank. It can be • Are they cracked? removed and cleaned with a can of carb cleaner or •...

  • Page 38: Evaporative (Evap) Emissions System

    Starting with the 2008 season, an EVAP sys- Unvented Vented tem has been offered in areas that require it. MTD has two systems that can be used. The first one is a char- coal canister system and the second (available starting in the 2009 model year) is redesigned EVAP fuel tank.
  • Page 39 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 4: The Fuel System and Governor The activated charcoal inside the canister Troubleshooting absorbs the hydrocarbons allowing the air to Table 1: pass through and out to the atmosphere. When the engine is running, the vacuum inside Symptom Cause the carburetor insulator is used to draw the...

  • Page 40: Charcoal Canister Fuel Tank

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 4: The Fuel System and Governor Charcoal canister fuel tank Remove the top two screws and remove the tank. See Figure 4.14. To remove/replace the fuel tank: Drain the tank. Disconnect the fuel line from the tank.

  • Page 41: Roll Over Valve Vent

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 4: The Fuel System and Governor Roll over valve vent With the grommet on the roll over valve, install the roll over valve by pressing it into the opening To remove/replace the roll over valve: in the tank.

  • Page 42: Charcoal Canister

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 4: The Fuel System and Governor Apply a vacuum to the roll over valve. Charcoal canister See Figure 4.18. To remove/replace the charcoal canister: Remove the fuel tank by following the steps described in the Charcoal canister fuel tank sec- tion of this chapter.

  • Page 43: Evap Fuel Tank

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 4: The Fuel System and Governor EVAP fuel tank To remove/replace the fuel tank: Starting with the 2009 model year, an EVAP fuel tank Drain the tank. will be used in place of the charcoal canister system to Disconnect the fuel line from the tank.

  • Page 44: Manual Choke

    Autochoke If the engine is equipped with a manual choke, the The MTD engine uses a simple autochoke system that choke must be closed to start the engine and opened is similar to the old style air vane governors. When the when the engine starts.

  • Page 45: 1P61/1P65

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 4: The Fuel System and Governor 1P61/1P65 1P70 To remove/replace the air vane: The 1P70 autochoke uses an air door that functions the same way as the air vane described earlier. NOTE: The choke linkage can be slightly bent to make adjustments if the choke is not opening or NOTE: There is no choke linkage in this system,...

  • Page 46: Primer

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 4: The Fuel System and Governor Slide the air door rod out of the blower housing. Primer See Figure 4.32. Another way to enrichen the fuel air mixture for start-up is the primer.

  • Page 47: Carburetors

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 4: The Fuel System and Governor To remove/replace the primer: Carburetors Remove the air filter housing by following the Troubleshooting the carburetor is a process of elimina- steps described in Chapter 3: Air Intake And Fil- tion.

  • Page 48: Disassembly And Rebuilding The Carburetor

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 4: The Fuel System and Governor • If varnish build-up is too extensive to clean, Disassembly and rebuilding the carburetor replace the carburetor. Clamp off the fuel line to prevent fuel spillage and remove it.
  • Page 49 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 4: The Fuel System and Governor • A square cross-section gasket seals the bowl to the body of the carburetor. NOTE: Air from the main jet emulsion port Remove the main jet by using a narrow-shank enters the central column near the top, then gets straight blade screwdriver.
  • Page 50 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 4: The Fuel System and Governor the pilot and transition ports, in an emulsified Carefully pry out the metering plug using a small screwdriver. See Figure 4.46. mixture. NOTE: In cut-away view, the passage by the metering port is visible.
  • Page 51 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 4: The Fuel System and Governor Soak the Carburetor body in a suitable solvent Check the top no load speed of the engine. until clean. See Figure 4.51. Rinse thoroughly. NOTE: The top no load speed will vary depend- ing on the application.

  • Page 52: Governor

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 4: The Fuel System and Governor Governor Governor arm The engine speed is controlled by a balance between To remove the governor arm from the governor the force applied by a spring (pulling the throttle open) shaft: and a flyweight mechanism within the engine applying 1a.

  • Page 53: Governor Shaft

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 4: The Fuel System and Governor Slide the arm onto the shaft. The flat on the top Slide the governor arm out of the engine block of the shaft should be roughly perpendicular to from the inside of the engine.

  • Page 54: Governor Cup And The Governor Gear

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 4: The Fuel System and Governor Install the sump by following the steps described Slide the governor shaft into the engine block from the inside of the engine. in Chapter 10: Disassembly. Carefully slide a new seal over the governor Rotate the governor shaft clockwise as far as it shaft and seat using a 1/4”...
  • Page 55 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 4: The Fuel System and Governor Slide the gear shaft out of the gear and cup. See Figure 4.60. Governor gear Gear shaft Governor cup Governor cup washer Figure 4.60 Install by following the above steps in reverse order.
  • Page 56 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 4: The Fuel System and Governor www.mymowerparts.com...

  • Page 57: Chapter 5: Lubrication

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 5: Lubrication CHAPTER 5: LUBRICATION Oil type and quantity Oil dip stick Use a 4-stroke, or an equivalent high detergent, pre- To check the oil level: mium quality motor oil certified to meet or exceed NOTE: Be sure to check the engine on a level American Petroleum Institute (A.P.I.) requirements for surface with the engine stopped.

  • Page 58: Dip Stick Tube Removal

    Dip stick tube removal Lubrication system Some MTD engines come with a dip stick tube, MTD uses a splash lube system for it’s vertical shaft depending on the application. See Figure 5.3. engines. The governor gear has paddles on it that “splashes”...

  • Page 59: Pcv

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 5: Lubrication The second oil passage runs along the bottom side of the cylinder. This is the oil return passage. As the name The PCV valve is located under the flywheel and implies, it allows the oil collecting in the cylinder head allows the crankcase pressure to escape.
  • Page 60 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 5: Lubrication The cover and gasket can be separated from the Inspect the disc for any signs of dirt, damage or chamber. See Figure 5.9. leaking. Inspect the folded wire mesh in the chamber . See Figure 5.11.
  • Page 61 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 5: Lubrication Reassemble the PCV. Tighten the cover bolts to a torque of 27 in-lbs. (3 Nm). Inspect the PCV tubing for cracks, brittleness or signs of leaking. Replace the PCV tube if any are found.
  • Page 62 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 5: Lubrication www.mymowerparts.com...

  • Page 63: Chapter 6: Starters

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 6: Starters CHAPTER 6: STARTERS Recoil Starter Removal Remove the engine cover and replace the fuel cap. To remove recoil assembly from the engine: Remove the three nuts that secure the recoil NOTE: Some engines are not equipped with an assembly and fan shroud to the engine using a engine shroud, depending on the application.

  • Page 64: Starter Cup

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 6: Starters Install a starter cup by placing the starter cup on Starter Cup the flywheel allowing the protrusion on the bot- The starter cup can either be cast into the flywheel or tom of the starter cup to rest inside the dimple in be a steel cup that is bolted to the flywheel depending the flywheel.

  • Page 65: Starter Rope

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 6: Starters Starter Rope Wind the spring completely. Then relieve it min- imum 1 full turn, counting when the pulley knot The most common failure mode for most recoil assem- aligns with the rope bushing in the housing.

  • Page 66: Starter Pulley And Recoil Spring

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 6: Starters Starter pulley and recoil spring NOTE: If starter rope tension needs to be The recoil spring is nested within the starter pulley and adjusted, there is room between the recoil hous- both parts are assembled as a single part number.
  • Page 67 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 6: Starters Inspect the pawls and torsion springs for wear and damage. See Figure 6.10. NOTE: Evaluate the damage, including parts prices and local labor rates. In some parts of the country, it makes economic sense to replace the complete assembly, in other areas labor rates Torsion springs...

  • Page 68: Electric Starter Relay

    Electric starter relay pound such as Loctite 242 (blue) to the threads The electric starter on the MTD engine uses a relay of the shoulder screw, and install the screw. that acts as a remote switch instead of a solenoid, Tighten it to a torque of 71 - 89 in-lb.

  • Page 69: Testing The Starter Relay

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 6: Starters Disconnect the relay’s ground lead from the mid- Testing the starter relay dle tab of the blade brake switch. To test the starter relay: See Figure 6.14. Unplug the starter harness. Unbolt the relay from the engine.
  • Page 70 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 6: Starters Connect the ground lead to the ground side of a Reconnect the DMM with it still on the Ohms (Ω) 12V power source. See Figure 6.16. scale. See Figure 6.18. Ground lead Ground side of power source...

  • Page 71: Electric Starter

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 6: Starters Electric starter To remove/replace the electric starter: NOTE: If replacing the starter, make sure both dowel tubes are in the engine block. Disconnect the engine harness. See Figure 6.21. Remove the screw that secures the starter relay and oil dip stick tube to the engine block using a 10mm wrench.

  • Page 72: Schematic

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 6: Starters Schematic www.mymowerparts.com...

  • Page 73: Chapter 7: Ignition System

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 7: Ignition System CHAPTER 7: IGNITION SYSTEM Trouble shooting the ignition system The purpose of the ignition system is to provide a spark NOTE: The spark should be a minimum of 10 Kv in the combustion chamber at the proper time to ignite (10,000 volts) at pull over speed.
  • Page 74 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 7: Ignition System 3d. Alternatively, a jumper wire could be con- 3b. Connect an Ohm meter between the termi- nal and a ground point. The reading should nected to the same locations. Use a com- approach zero when the bail is released or mercially available spark checker to see if the switch is turned off, closing the con-...
  • Page 75 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 7: Ignition System 3h. Resistance (Ohms) should be infinite (O.L) 4b. Presence or absence of strong spark, with with the bail released. See Figure 7.6. the stop switch and wire known to be good, is generally enough to identify the ignition coil as good or bad.
  • Page 76 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 7: Ignition System 4d. At operating speed, the ignition should pro- 4f. Resistance in the primary windings of the duce voltage approaching 12,000. ignition module, measured between the See Figure 7.9. spade terminal and the laminations, was observed to be in the 550-650 Ω...
  • Page 77 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 7: Ignition System • Resistance figures that are vastly lower may Inspect the flywheel. indicate a short in the windings being tested. The flywheel is a frequently forgotten component of the •...

  • Page 78: About The Spark Plug

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 7: Ignition System About the spark plug Spark plug removal • The spark plug is a Torch model F6RTC, gapped Disconnect and ground the spark plug wire. to .024”-.032” (.60-.80 mm). Remove the spark plug using a 13/16”...

  • Page 79: Ignition Module

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 7: Ignition System Ignition module Installing the module and setting the air gap The ignition system is either a capacitive discharge or a NOTE: If just setting the air gap, loosen the inductive discharge magneto, depending on the appli- module mounting screws first then follow the cation, contained in a single module.

  • Page 80: Engine Brake And Stop Switch (If Equipped)

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 7: Ignition System Tighten the module mounting screws to a torque Engine brake and stop switch (if equipped) of 18.5 ft-lbs (10Nm). The stop switch and brake (for lawn mower applica- Rotate the flywheel to remove the feeler gauge.

  • Page 81: Adjusting The Brake Assembly (If Equipped)

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 7: Ignition System Disconnect the connector in the lead that goes Adjusting the brake assembly (if equipped) to the module. Disconnect and ground the spark plug wire. Remove the two bolts securing the brake Remove the recoil assembly and blower housing assembly.

  • Page 82: Flywheel

    Position the brake assembly so that the edge of Flywheel the brake pad that is nearest the slotted hole is There are two types of flywheels available for the MTD roughly .050” (1.27mm) from the flywheel, then engine. An aluminum flywheel and a 3-piece cast iron tighten the screws.
  • Page 83 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 7: Ignition System 2a. Loosen the flywheel nut until it is a couple of 2b. Remove the flywheel by applying a sharp threads past the end of the crank shaft blow to the crankshaft using a brass drift using a 19mm wrench.
  • Page 84 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 7: Ignition System 2c. Inspect the key, keyway, and tapered mating surfaces of the flywheel and crankshaft. IMPORTANT: The taper in flywheel and the on See Figure 7.27. the crankshaft must be clean and dry. The fly- wheel is held in place by the friction fit between Key flat parallel to the threads the flywheel and the crankshaft, not the key.

  • Page 85: Chapter 8: Exhaust

    NOTE: A blocked muffler will result in poor per- formance. If a muffler is completely blocked the engine may not start. The MTD engine uses one of two different mufflers; a standard muffler covered here or a catalytic converter muffler that will be covered later in this chapter.

  • Page 86: Catalytic Converter Muffler

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 8: Exhaust Clean the cylinder head and muffler of any resid- Catalytic converter muffler ual gasket material. The CARB (California) compliant engines use a cata- Using a new gasket, install the muffler by follow- lytic converter muffler.
  • Page 87 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 8: Exhaust The air injector works as follows: To service/replace the air injector: • Between the exhaust pulses of the engine, there Remove the two screws that secure the air injec- is low pressure in the exhaust.
  • Page 88 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 8: Exhaust Install the inlet screen cover and tighten the screws to a torque of 44 in lbs (5 Nm). Clean the gasket material from the air injector and the muffler. See Figure 8.8. Clean the gasket material from these surfaces Graphite gasket...

  • Page 89: Chapter 9: Cylinder Head

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 9: Cylinder Head CHAPTER 9: CYLINDER HEAD The Cylinder head of the MTD engine can be removed Remove the spark plug using a 13/16” or 21mm without removing the engine from the application.
  • Page 90 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 9: Cylinder Head Lift the cylinder head off of the engine. Pivot the rocker arms aside, or remove them completely, and remove the push rods. NOTE: Early production had the alignment dow- NOTE: Once broken-in, the rocker arm should els fit in the head bolt holes next to the push rod be kept with its corresponding valve.

  • Page 91: Valves

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 9: Cylinder Head Carefully clean all sealing surfaces of all gasket Valves residue. Do not scratch the sealing surfaces. Valves and valve parts, like springs and keepers, are NOTE: Make a visual inspection of the valves not available as service parts.
  • Page 92 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 9: Cylinder Head Inspect the valve stem. See Figure 9.11. NOTE: Only the intake valve has a valve guide seal. See Figure 9.9. Inspect for a burnt edge Figure 9.11 Inspect the valve springs.

  • Page 93: Chapter 10: Crankshaft, Piston And Connecting Rod

    Crank shaft NOTE: The MTD engine is NOT to be opened under warranty. If an internal engine failure Sump occurs during the warranty period, replace the whole engine, no short blocks.
  • Page 94 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 10: Crankshaft, piston and Connecting Rod Remove the connecting rod cap using a 10mm wrench. See Figure 10.5. NOTE: Early production of the 1P70 series engines had a steel cam shaft. See Figure 10.3. Place a match mark here Remove the connecting rod bolts...

  • Page 95: Crank Shaft Inspection

    Chapter 10: Crankshaft, piston and Connecting Rod Push the piston out of the cylinder. The internal components of the MTD engine are not available as service parts. The intent of this chapter is Remove the piston rings from the piston using a to provide the technician the procedures to examine an pair of piston ring pliers.

  • Page 96: Piston Inspection

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 10: Crankshaft, piston and Connecting Rod Measure the crankpin using a vernier caliper or Piston Inspection a micrometer. See Figure 10.10. Clean the piston and remove all carbon from the rings and ring groves.

  • Page 97: Connecting Rod Inspection

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 10: Crankshaft, piston and Connecting Rod Connecting rod inspection NOTE: The top ring is symmetrical and the mid- Inspect the connecting rod for cracks or any dle ring has a tapered profile. The larger radius signs of damage.

  • Page 98: Cylinder Inspection

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 10: Crankshaft, piston and Connecting Rod Compare the measurements to those that are Cylinder inspection listed in the chart at the end of the chapter. Clean and inspect the cylinder, inside and out. Inspect the cylinder cross hatch.

  • Page 99: Bearings

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 10: Crankshaft, piston and Connecting Rod Bearings Reassembly There are two bearings to inspect; a plain bearing in Clean the cylinder the sump and a ball bearing in the cylinder block. To 1a.
  • Page 100 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 10: Crankshaft, piston and Connecting Rod 4d. Tap the piston through the ring compressor Insert the crankshaft into the cylinder block bear- ing. into the cylinder using a wooden hammer handle.
  • Page 101 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 10: Crankshaft, piston and Connecting Rod Install the valve tappets. See Figure 10.26. If removed, install the governor arm by following the steps described in Chapter 4: Fuel systems and Governor. If removed, install the oil return deflector.
  • Page 102 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 10: Crankshaft, piston and Connecting Rod Install the cylinder head by following the steps 10d. Using a seal protector, slide the sump on to the crank shaft. described in Chapter 9: Cylinder head. NOTE: The governor arm must slide between Install the muffler by following the steps the governor cup and the governor arm stop.

  • Page 103: Engine Specifications Chart

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 10: Crankshaft, piston and Connecting Rod Engine specifications chart www.mymowerparts.com...
  • Page 104 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 10: Crankshaft, piston and Connecting Rod www.mymowerparts.com...
  • Page 105 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 10: Crankshaft, piston and Connecting Rod www.mymowerparts.com...

  • Page 106: Engine Torque Values Chart

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 10: Crankshaft, piston and Connecting Rod Engine torque values chart Table 1: Fastener Torque 1P61 1P65 1P70 Blower housing studs 89 in-lbs (10 Nm) 89 in-lbs (10 Nm) 89 in-lbs (10 Nm) Breather cover 27 - 35 in-lbs (3 - 4 Nm) 27 - 35 in-lbs (3 - 4 Nm)

  • Page 107: Chapter 11: Failure Analysis

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 11: Failure Analysis CHAPTER 11: FAILURE ANALYSIS A properly maintained engine will provide years of ser- Abrasive Ingestion vice. Occasionally an engine will fail. An important part Abrasive Ingestion is when hard particles are intro- of working on engines is finding out why they failed.
  • Page 108 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 11: Failure Analysis This can be identified by the scoring along the vertical axis of the piston and cylinder wall or the NOTE: Dirt can also work its way through a cross hatch on the cylinder wall being worn off.
  • Page 109 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 11: Failure Analysis A symptom of abrasive ingestion is smoky exhaust. As Because the oil absorbs the abrasive particles, the cylinder walls wear; pressure from the combustion the engine components that are immersed in oil chamber blows by the piston and pressurizes the will show definite signs of abrasive ingestion engine sump.

  • Page 110: Insufficient Lubrication

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 11: Failure Analysis The hall mark of a lubrication failure is the pres- Insufficient lubrication ence of discoloration and/or metal transfer on all The bearing surfaces in an engine are not smooth. As friction surfaces within the engine.

  • Page 111: Engine Overspeed

    On most engine that would be about an inch below the wrist pin, but on the MTD engine it is at the wrist pin. The force on the connecting rod is greatest when the piston transitions from the upward stroke to the downward stroke.

  • Page 112: Overheated

    This warping of the head allows the head gasket to Overheated leak. A leaking head gasket allows the compressed The MTD engines are air cooled engines. Because of gases in the engine to escape, lowering the compres- this, cleanliness of the engine is very important to the sion in the engine and hurting engine performance.

  • Page 113: Mechanical Breakage/ Wear

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Chapter 11: Failure Analysis Mechanical Breakage/ Wear Detonation/pre-ignition Sometimes an engine fails because a part breaks. Detonation is the undesirable condition of the fuel There are generally three causes of a broken part, out- spontaneously combusting in the combustion chamber side of the previously discussed engine failures.

This manual is also suitable for:

P65 seriesP70 series

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