MTD T65 Series Shop Manual
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MTD T65 Series Shop Manual

MTD T65 Series Shop Manual

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Professional Shop Manual
T65 Series Vertical Shaft Engines
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 2013 MTD Products Inc. All Rights Reserved
MTD Products Inc. - Product Training and Education Department

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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 2013 MTD Products Inc. All Rights Reserved MTD Products Inc. - Product Training and Education Department...

  • Page 3: Table Of Contents

    Table of Contents Chapter 1: Introduction Professional Service Manual Intent..............1 Safety .........................1 Fasteners ......................3 Assembly Instructions ..................3 Model and Serial Number ...................5 Maintenance .......................5 Spark Plugs ......................6 Air Filter ......................7 Oil Type and Capacity ..................8 Changing the oil ....................10 Fuel system ......................11 Servicing the Fuel System ................11 Fuel Filter ......................11...
  • Page 4 Chapter 4: The Fuel System and Governor Inspecting the Fuel ...................38 Test Fuel for Alcohol ..................38 The Fuel Filter ....................39 Evaporative (EVAP) Emissions System ............39 Charcoal Canister Fuel Caps ................39 Fuel Tank Vent ....................40 The Fuel Tank ....................41 Autochoke ......................42 Temperature Compensator ................43 Primer .......................44...
  • Page 5 Chapter 8: Exhaust Muffler ......................77 Chapter 9: Cylinder Head Cylinder Head ....................79 Valves ......................82 Chapter 10: Crankshaft, piston and Connecting Rod Engine Disassembly..................85 Crankshaft Inspection ..................88 Piston Inspection ....................89 Connecting rod Inspection ................91 Cylinder Inspection ...................92 Bearings ......................93 Reassembly .....................94 Engine Specifications Chart ................98 Engine Torque Values Chart ................99 Chapter 11: Failure Analysis...

  • Page 7: Chapter 1: Introduction

    • Using common sense in operation and safety is assumed. • In no event shall MTD be liable for poor text interpretation or poor execution of the procedures described in the text. • If the person using this manual is uncomfortable with any procedures they encounter, they should seek the help of a qualified technician or MTD Technical Support.
  • Page 8 T65 Series Vertical Shaft Engines • Be prepared in case of emergency: ! CAUTION ! CAUTION Keep a fire extinguisher nearby Keep a first aid kit nearby Keep emergency contact numbers handy • Replace any missing or damaged safety labels on shop equipment.

  • Page 9: Fasteners

    Introduction Fasteners • Most of the fasteners used on the MTD engine are metric. Some are fractional inches. For this reason, wrench sizes are frequently identified in the text, and measurements are given in U.S. and metric scales. • If a fastener has a locking feature that has worn, replace the fastener or apply a small amount of releas- able thread locking compound such as Loctite®...
  • Page 10 T65 Series Vertical Shaft Engines MTD Vertical Engine Model Designators 1 P 6 1 M U A Major Revision Starter/Alternators 1=Recoil start Change 2=Electric start (12V) 3=E. start/alt. 18W 4=E. start/alt. 3A/5A 5= AutoChoke/ Recoil Compliance 6= AutoChoke/Electric Start 7= AutoChoke/Electric Start/Alt...

  • Page 11: Model And Serial Number

    Introduction Model and serial number The model and serial number can be found on a white sticker with a bar code. The sticker is usually located near the dipstick. See Figure 1.1. Model /serial number Dipstick Figure 1.1 NOTE: The serial number will always start with the model number. Maintenance The recommended maintenance intervals listed in this manual are a guideline.

  • Page 12: Spark Plugs

    Cleaning the spark plug: NOTE: MTD does not recommend cleaning spark plugs. Use of a wire brush may leave metal deposits on the insulator that causes the spark plug to short out and fail to spark. Use of abrasive blast for cleaning may cause damage to ceramic insulator or leave blast media in the recesses of the spark plug.

  • Page 13: Air Filter

    The first is a round paper pleated filter. The second is a round foam filter. See Figure 1.3. • Air filters used on the MTD engine are designed to prevent particles larger than 3-5 micron from passing through into the engine.

  • Page 14: Oil Type And Capacity

    T65 Series Vertical Shaft Engines Oil type and capacity The recommended oil for MTD engines is an SAE 10W-30 oil with an SM API rating or better. The oil capacity is 20 fl.oz (0.6 liters). • Check the oil level daily, before starting the engine. Change the oil more frequently in severe operating conditions such as high ambient temperature, dusty conditions, or high load use in exceptionally thick grass.
  • Page 15 Introduction Threaded NOTE: There are two types of dip sticks that can be found on the T series engine; a short threaded dip stick and a quarter turn extended dip stick See Figure 1.4. 1/4 turn Threaded 1/4 turn Figure 1.4 To check the oil with a threaded dip stick: Twist and remove the dip stick from the engine.

  • Page 16: Changing The Oil

    T65 Series Vertical Shaft Engines Changing the oil NOTE: If the engine has been running, allow the engine to cool before doing any mainte- Siphon nance work. NOTE: The oil should be changed after the first 5 hours of operation and every 25 hours there after.

  • Page 17: Fuel System

    Fuel used in MTD outdoor power equipment should be no more than 30 days old. Because it may already have been stored at the refinery or gas station for a week or more, fuel should be purchased in small quantities and stored in safety approved gas cans with the caps closed.

  • Page 18: Valve Lash

    T65 Series Vertical Shaft Engines Valve lash Valve lash is the clearance between the top of the valve stem and the rocker arm. The valve lash should be checked after the first 25 hours of use and every 100 hours after that. Valve lash can be checked and adjusted using the following steps:.
  • Page 19 Introduction 0.005” feeler gauge Check valve lash between each valve stem and rocker arm using a feeler gauge. Intake valve lash (top valve) should be 0.004” - 0.006” (0.10 - 0.15 mm). See Figure 1.13. Setting intake valve lash Figure 1.13 Exhaust valve lash (bottom valve) should be 0.006”...

  • Page 20: Exhaust System

    T65 Series Vertical Shaft Engines Exhaust system The exhaust system is a frequently overlooked component of an engine. It is important to make sure the muffler is in good condition and free of blockage. NOTE: A blocked muffler will result in poor performance. If a muffler is completely blocked, the engine may not start.

  • Page 21: Chapter 2: Basic Troubleshooting

    Also check attachments for damage and make sure they are firmly mounted. Steps to troubleshooting NOTE: The steps and the order of the steps that follow are a suggested approach to troubleshooting the MTD engine. The technician does not necessarily have to follow them as described in this chapter.
  • Page 22 T65 Series Vertical Shaft Engines IV. Unusual exhaust tone. There are tools that the technician can use in order to define the problem, such as: Interview the customer. 1a. Get a good description of their complaint. 1b. If it is an intermittent problem, verify what conditions aggravate the problem as best as possible.

  • Page 23: Identify Factors That Could Cause The Problem

    Basic Troubleshooting Identify factors that could cause the problem This is the second step in the troubleshooting process. Crankshaft will not turn. A. Starter not working. This can be an electrical failure or a mechanical failure. The likely suspects are: A dead battery.
  • Page 24 T65 Series Vertical Shaft Engines Run the engine with a spark tester in-line between the spark plug wire and the spark plug or use an oscilloscope and see if the spark goes away at the same time the engine dies.
  • Page 25 Basic Troubleshooting V. Makes unusual smoke when running. a. Black smoke, usually heavy, usually indicates a rich air fuel mixture. • Not enough air: air flow blockage or a partially closed choke. • Too much fuel: carburetor float or float valve stuck or metering / emulsion issues with the car- buretor.
  • Page 26 T65 Series Vertical Shaft Engines chirping noise. • Confirm with a compression test and leak-down test. e. Unusual exhaust tone. Splashy • Splashy idle usually indicates a slight rich condition. • May indicate an exhaust blockage, usually slightly muffled. Backfire •...

  • Page 27: Repairing The Problem

    Basic Troubleshooting Repairing the problem The third step in the troubleshooting process is to repair the problem. This step consists of: A. Form a diagnosis by using all of the information gathered from the troubleshooting that was performed. B. Physically perform the repair. The fourth, and hopefully final, step in the troubleshooting process is the follow through.

  • Page 28: Prime Test

    T65 Series Vertical Shaft Engines Prime test To perform a prime test: Prime the engine through the carburetor throat using a squirt bottle, filled with clean fresh gasoline. Make sure the throttle is in the run position. Attempt to start the engine.
  • Page 29 Basic Troubleshooting Connect tester to compressed air. Adjust the regulator knob until the needle on the gauge is in the yellow or set area of the gauge. See Figure 2.2. Connect the tester to the adapter. NOTE: Open the valve, if equipped. NOTE: If the engine rotates it was not at top dead center.

  • Page 30: Compression Test

    T65 Series Vertical Shaft Engines Compression test To perform a compression test: NOTE: Compression should be in the range of 55 - 85 PSI (3.8 - 5.9 Bar). • Disconnect the high-tension lead from the spark plug and ground it well away from the spark plug hole.

  • Page 31: Pcv Testing

    2.5. NOTE: Less than (between zero and -1”) (-2.54cm) of water is a typical reading. NOTE: Experimentation by MTD’s Training and Education Department has revealed the following character- istics of MTD engines: • A leaky PCV system will not build-up substantial case pressure.

  • Page 32: Troubleshooting Flow Charts

    T65 Series Vertical Shaft Engines Troubleshooting flow charts Ignition Troubleshooting Engine runs Engine will erratically or shuts not start off, restarts Check for spark Spark No Spark Replace spark plug Check for the correct spark plug Isolate engine from equipment and repeat...

  • Page 33: Engine Operation Problems

    Basic Troubleshooting Engine Operation Problems ENGINE KNOCKS OVERHEATS Associated equipment loose or Excessive engine loading improperly adjusted Check for excessive carbon in Low oil level or wrong viscosity oil combustion chamber Cooling air flow obstructed or Loose flywheel examine key, key way and proper flywheel nut torque clogged cooling fins Ignition timing or...
  • Page 34 T65 Series Vertical Shaft Engines Engine Operation Problems SURGES OR RUNS UNEVENLY EXCESSIVE OIL CONSUMPTION Fuel cap vent obstructed Oil level above full Dirty carburetor or air filter Wrong viscosity oil Carburetor improperly adjusted Excessive engine speed Governor sticking, binding or...
  • Page 35 Basic Troubleshooting Engine Operation Problems ENGINE VIBRATES ENGINE MISFIRES EXCESSIVELY Carburetor improperly adjusted Bent crankshaft Attached equipment out Wrong or fouled spark plug of balance Valves sticking or not Loose mounting bolts seating properly Ignition timing or If applicable counter balance not incorrect spark plug properly aligned Excessive carbon build up...
  • Page 36 T65 Series Vertical Shaft Engines Engine Operation Problems LACKS POWER BREATHER PASSING OIL Oil level too high Air intake obstructed Lack or lubrication or improper Excessive RPM or improper lubrication governor setting Damaged gaskets, seals Carburetor improperly adjusted or "O" rings...

  • Page 37: Chapter 3: Air Intake System

    NTAKE YSTEM CHAPTER 3: AIR INTAKE SYSTEM Air filter To access the air filter: NOTE: The T65 engine comes equipped with either a pleated paper filter or a foam filter. The procedure to access the filter is the same for both types. Rotate air filter cover counter-clockwise.

  • Page 38: Air Filter Housing

    T65 Series Vertical Shaft Engines Air Filter Housing To remove the air filter housing: Remove the air filter by following the steps described in the previous section. Remove the two nuts that hold the air filter body to the carburetor mounting studs. See Figure 3.3.

  • Page 39: Carburetor Insulator

    NTAKE YSTEM Carburetor Insulator To avoid personal injury or property damage, use extreme care in handling gasoline. Gaso- ! WARNING ! WARNING line is extremely flammable and the vapors are explosive. Serious personal injury can occur when gasoline is spilled on yourself and/or your clothes which can ignite. Wash your skin and change clothes immediately To remove/replace the carburetor insulator: Remove the air filter housing by following the previ-...
  • Page 40 T65 Series Vertical Shaft Engines Choke rod Air vane Lift the Autochoke Air Vane off of the its pivot. Unhook the choke rod from the carburetor. See Figure 3.8. Figure 3.8 Carburetor gasket If the engine is not equipped with an auto- choke, remove the carburetor gasket.
  • Page 41 See Figure 3.11. Carburetor Calibration Number Figure 3.11 NOTE: MTD gets carburetors from several suppliers. Suppler trademark When ordering carburetor kits, the carburetor’s manufacturer, calibration code and serial number are needed.
  • Page 42 T65 Series Vertical Shaft Engines...

  • Page 43: Fuel Line

    NOTE: When working on the fuel systems, look at the whole system. A problem will rarely be isolated to one component. Fuel Line The fuel line used by MTD is GREENBAR . This is NBR intermediate layer NBR inner liner a multi-layer fuel line that meets the current EPA guide- lines.

  • Page 44: Inspecting The Fuel

    This results in less power for the engine. A 10% ethanol (E10) mix is acceptable for MTD engines. Anything higher than that will result in perfor- Figure 4.2 mance issues and is not covered by warranty.

  • Page 45: The Fuel Filter

    To reduce or eliminate the release of fuel vapors into the atmosphere, an evaporative (EVAP) emis- sions system is used. Starting with the 2008 season, an EVAP system has been offered in areas that require it. MTD uses a charcoal canister fuel cap on the T65 series engines.

  • Page 46: Fuel Tank Vent

    T65 Series Vertical Shaft Engines Fuel tank vent The fuel tank vent performs the important task of allow- ing air into the fuel tank. As fuel is being used by the engine, the fuel level in the tank drops. The dropping fuel level then creates a vacuum in the tank.

  • Page 47: The Fuel Tank

    YSTEM AND OVERNOR The fuel tank When working around the fuel system, do not bring any sources of heat, spark, or open flame ! WARNING ! WARNING near the work area. To remove the fuel tank: Drain the fuel out of the fuel tank into an approved container.

  • Page 48: Autochoke

    T65 Series Vertical Shaft Engines Autochoke The MTD engine uses a simple autochoke system that is similar to the old style air vane governors. When the Air vane engine is at rest a spring holds the choke in the closed position.

  • Page 49: Temperature Compensator

    YSTEM AND OVERNOR To remove/replace the air vane: Air Vane Unplug the spark plug. Drain the fuel out of the fuel tank into an approved container. Disconnect the fuel line from the tank. Remove the recoil starter by following the procedures described in Chapter 6: Starters Lift the blower housing off of the engine.

  • Page 50: Primer

    T65 Series Vertical Shaft Engines Primer Another way to enrichen the fuel air mixture for start- up is the primer. The primer is a simple pump that pressur- Primer Carburetor izes the float chamber, forcing fuel out the main nozzle.

  • Page 51: Carburetors

    YSTEM AND OVERNOR Squeeze the two sets of tabs together and push the primer out of the housing. See Figure 4.18. Install the primer by following the above steps in reverse order. Test run the engine before returning to service. Squeeze the barbs together, then push Figure 4.18...

  • Page 52: Disassembly And Rebuilding The Carburetor

    T65 Series Vertical Shaft Engines Disassembly and rebuilding the carburetor Bowl vent port Clamp off the fuel line to prevent fuel spillage and remove it. Remove the carburetor by following the steps described in Chapter 3: Air Intake and Filter.
  • Page 53 YSTEM AND OVERNOR NOTE: The float is not adjustable. Spring tension against Float the float valve begins to build from the horizontal position, putting progressively more pressure Compression between the tip of the valve and the seat. See Fig- spring ure 4.22.
  • Page 54 T65 Series Vertical Shaft Engines Emulsion air port: main jet NOTE: Fuel enters the central column through a Emulsion tube port about 1/2” (1cm) from the bottom, to help prevent the ingress of any residue in Main jet the bottom of the bowl.
  • Page 55 YSTEM AND OVERNOR Air passage End view Examine the metering plug: See Figure 4.28. • Fuel, drawn from the central column via the long fuel feed leg, is metered by the brass orifice in the tip of the metering plug. •...
  • Page 56 T65 Series Vertical Shaft Engines Digital tachometer confirms safe NOTE: For mower applications, the idle speed is operating speed not normally critical because the operator is not provided with a throttle control. Check the top no load speed of the engine. See Figure 4.31.

  • Page 57: Governor

    YSTEM AND OVERNOR Governor The engine speed is controlled by a balance between the force applied by a spring (pulling the throttle open) and a flyweight mechanism within the engine applying force to the governor arm (pushing the throttle closed). See Figure 4.33.

  • Page 58: Governor Shaft

    T65 Series Vertical Shaft Engines Governor shaft To remove or replace the governor shaft: Remove the engine from the unit. Remove the governor arm by following the previ- ously described steps. Remove the sump by following the steps described in Chapter 10: Disassembly.
  • Page 59 YSTEM AND OVERNOR Slide the governor shaft through the engine block from the inside of the engine. Seal Carefully slide a new seal over the governor shaft and seat using a 1/4” deep well socket. See Figure 4.38. Install the hair pin clip. Figure 4.38 10.

  • Page 60: Governor Cup And The Governor Gear

    T65 Series Vertical Shaft Engines Governor cup and the governor gear Remove these screws Remove the engine from the unit. Remove the sump by following the steps described in Chapter 10: Disassembly. Remove the two screws that hold the governor gear plate to the sump using a 10mm wrench.

  • Page 61: Chapter 5: Lubrication

    Lubrication CHAPTER 5: LUBRICATION Oil type and quantity The recommended oil for MTD engines is an SAE 10W-30 oil with an SM API rating or better. The oil capacity is 17.0- 20.3 fl.oz (0.5-0.6 liters). 14°F 32°F 50°F 68°F 86°F 104°F...

  • Page 62: Oil Dipstick

    Oil dipstick Threaded NOTE: There are two types of dip sticks that can be found on MTD engines; a threaded dip stick that was used on older engines and a quar- ter turn dip stick that is used on engines cur- rently being produced.

  • Page 63: Dipstick Tube Removal

    Lubrication Dipstick tube removal Some MTD engines come with a dip stick tube, depending on the application. See Figure 5.4. To remove/replace the dip stick tube: Remove the dip stick. Remove the screw at the top of the dip stick tube.

  • Page 64: Lubrication System

    T65 Series Vertical Shaft Engines Lubrication system MTD uses a splash lube system for it’s vertical shaft engines. The governor gear has paddles on it that “splashes” oil around the inside of the engine. See Figure 5.6. Governor gear Paddles Figure 5.6...

  • Page 65: Pcv

    Lubrication The function and test procedures for the PCV is cov- Autochoke Air Vane ered in Chapter 2: Basic Troubleshooting. To service the PCV: NOTE: If the engine is equipped with an autochoke, lift the Autochoke Air Vane off of the PCV Chamber Cover Screw, and set it off to the side of the engine.
  • Page 66 T65 Series Vertical Shaft Engines Inspect the oil drain-back port. Make sure it will allow oil to drain back into the engine. See Figure Drain-back port 5.12. Reassemble the PCV. Tighten the cover bolts to a torque of 27 in-lbs. (3 Nm).

  • Page 67: Chapter 6: Starter And Charging Systems

    Starters CHAPTER 6: STARTER AND CHARGING SYSTEMS Recoil Starter Removal To remove the recoil assembly from the engine: If the engine is installed on a mower, loosen the wing- nut that secures the starter rope eyelet to the handle- bars enough to provide clearance for the starter rope and slide the rope out.

  • Page 68: Starter Rope

    T65 Series Vertical Shaft Engines Starter Rope The most common failure mode for most recoil assem- blies is a broken rope. See Figure 6.2. Starter cord knot NOTE: If the spring was not damaged when the recoil sprung back, It is possible to simply remove the remnants of the old rope.
  • Page 69 Starters NOTE: If starter rope tension needs to be adjusted, there is room between the recoil housing and the pulley to wind-on more tension. See Figure 6.5. 10. Install the starter and tighten the starter nuts to a torque of 80 - 106 in lbs (9 - 12 Nm). Rope-return tension may be increased by winding the rope and pulley...

  • Page 70: Starter Pulley And Recoil Spring

    T65 Series Vertical Shaft Engines Starter pulley and recoil spring The recoil spring is nested within the starter pulley and both parts are assembled as a single part number. Eye protection should be worn if ! CAUTION ! CAUTION the starter pulley is to be removed.
  • Page 71 Starters L-shaped arm goes outside of the starter pawl, on installation NOTE: Beneath the pressure plate is a compression spring, and two starter pawls that are held in the disengaged position by two torsion springs. Inspect the pawls and torsion springs for wear and damage.
  • Page 72 T65 Series Vertical Shaft Engines Pressure Plate NOTE: The rolled end of the pawl fits in the recess in the starter pulley. The hooked end engages the starter cup. Both the roll and the hook face inward. NOTE: The extrusions on the pressure plate should...

  • Page 73: Chapter 7: Ignition System

    Ignition System CHAPTER 7: IGNITION SYSTEM Troubleshooting the ignition system The purpose of the Ignition System is to provide a spark in the combustion chamber at the proper time to efficiently ignite the fuel/air mixture. The steps in troubleshooting the Ignition System are: Examine the spark plug(s) by following the steps described in the spark plug section of this chapter.

  • Page 74: Troubleshooting The Stop Switch

    T65 Series Vertical Shaft Engines Troubleshooting the Stop Switch To access the stop switch: Drain the fuel out of the fuel tank into an approved container. Disconnect the fuel line from the tank. Remove the recoil starter by following the proce-...

  • Page 75: Troubleshooting The Module

    Ignition System Troubleshooting the Module • Normal performance of the coil is to produce at least 10,000 volts at starter-rope pull-through speed. See Figure 7.5. NOTE: Presence or absence of strong spark, with the stop switch and wire known to be good, is generally enough to identify the ignition coil as good or bad.
  • Page 76 T65 Series Vertical Shaft Engines Pull-over speed: waveform is half-way between 2nd and 3rd reticle (10,000 V.) • At pull-over speed (~ 600 RPM), voltage should be at least 10,000V. See Figure 7.8. NOTE: Flash-over voltage will vary with spark plug condition and gap.

  • Page 77: Ignition System

    Ignition System NOTE: Intermittent failure requires tests for voltage Magnets and resistance to be made when the engine is cold, and again when it is hot. Typical cus- tomer complaint: “It stops after I mow for 10 minutes and I can’t get it to re-start”. •...

  • Page 78: About The Spark Plug

    T65 Series Vertical Shaft Engines About the spark plug • The Spark Plug is a F5RTC, part #951-14437, gapped to 0.024” - 0.031” (0.6 - 0.8 mm). • Wear rate will vary somewhat with severity of use. If the edges of the center electrode are rounded-off, or any other apparent wear / damage occurs, replace the spark plug before operating failure (no start) occurs.

  • Page 79: Ignition Module

    Ignition System Ignition Module To removal an Ignition Module: Unplug the spark plug. Stop Switch Drain the fuel out of the fuel tank into an approved container. Disconnect the fuel line from the tank. Remove the recoil starter by following the procedures described in Chapter 6: Starters Ignition Module Lift the blower housing off of the engine.

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

    T65 Series Vertical Shaft Engines Engine brake and stop switch (if equipped) The stop switch and brake (for lawn mower applications) must be able to stop the blade from rotating within 3.0 sec- onds after the release of the safety bail, per ANSI B71.1-2003 standard.

  • Page 81: Flywheel

    Ignition System Flywheel To remove the flywheel: A couple of threads past the end of the crank shaft Unplug the spark plug. Drain the fuel out of the fuel tank into an approved container. Disconnect the fuel line from the tank. Remove the recoil starter by following the procedures described in Chapter 6: Starters Lift the blower housing off of the engine.
  • Page 82 T65 Series Vertical Shaft Engines Key flat parallel to the threads If the flywheel shows any signs of ! CAUTION ! CAUTION physical damage such as cracks, bro- ken vanes (if equipped), or a damaged Taper keyway, replace it. A damaged flywheel poses a threat of a burst failure.

  • Page 83: Chapter 8: Exhaust

    Exhaust CHAPTER 8: EXHAUST Muffler The exhaust system is a frequently overlooked component of an engine. It is important to make sure the muffler is in good condition and free of debris and/or insects. NOTE: A blocked muffler will result in poor performance. If a muffler is completely blocked the engine may not start.
  • Page 84 T65 Series Vertical Shaft Engines Slide the muffler off of the studs. See Figure 8.3. NOTE: The exhaust gasket is made of a graphite material. It will stick to the sealing surfaces when pressure is applied, tearing when pressure is relieved. The gasket can only be used one time.

  • Page 85: Chapter 9: Cylinder Head

    Cylinder head CHAPTER 9: CYLINDER HEAD Cylinder Head The Cylinder head of the MTD engine can be removed without removing the engine from the application. To remove the cylinder head: NOTE: If possible, It is recommended that the machine be positioned on the bench so that the cylinder head is vertical for removal.
  • Page 86 T65 Series Vertical Shaft Engines Loosen the jam nuts and fulcrum nuts that secure the rocker arms using a 10mm wrench and a 14mm wrench. See Figure 9.3. Pivot the rocker arms aside, or remove them com- pletely, and remove the push rods.
  • Page 87 Cylinder head 15. Position the cylinder head on the engine block. 16. Install the 4 head bolts, and tighten them to a step torque of 21 - 22 ft lbs (28 - 30 Nm) in an alternating diagonal pattern. See Figure 9.6. NOTE: The bolt closest to the exhaust valve must be the last bolt tightened.

  • Page 88: Valves

    T65 Series Vertical Shaft Engines Valves Valves and valve parts, like springs and keepers, are not available as service parts. The valves and valve seats can be serviced by grinding and lapping or the head can be replaced. Depending on local machine and labor costs, it is probably more economical to replace the cylinder head versus servicing the valves.
  • Page 89 Cylinder head Inspect the valve seat. See Figure 9.9. • Valve seats are 45 degrees, with a 15 degree top- ping cut and a 75 degree narrowing cut. • Seat width should be 0.043” - 0.050” (1.1 - 1.3 mm) with a margin of 0.024”...
  • Page 90 T65 Series Vertical Shaft Engines...

  • Page 91: Chapter 10: Crankshaft, Piston And Connecting Rod

    Crankshaft, piston and connecting rod CHAPTER 10: CRANKSHAFT, PISTON AND CONNECTING ROD There are a a few different paths that can be followed when disassembling an engine. This chapter will cover the removal of components in one order, but it is written so that the technician can jump around to the component being removed.
  • Page 92 T65 Series Vertical Shaft Engines NOTE: The thrust washer should be removed when the sump is removed. Cam shaft Remove the camshaft. See Figure 10.2. Timing marks NOTE: Align the timing marks to allow easier removal of the cam shaft and to help protect the compression relief from damage.
  • Page 93 Crankshaft, piston and connecting rod NOTE: Rotating the crankshaft after the connecting rod Connecting rod bolts are removed will help to separate the con- necting rod from the cap. See Figure 10.5. Figure 10.5 15. Push the piston out of the cylinder. 16.

  • Page 94: Crankshaft Inspection

    T65 Series Vertical Shaft Engines Crankshaft inspection Bearing contact Inspect the crankshaft journals for galling, scoring, area pitting or any other form of damage. Measure the journals at the bearing contact points using a vernier caliper or a micrometer. See Figure 10.8.

  • Page 95: Piston Inspection

    Crankshaft, piston and connecting rod Piston Inspection Clean the piston and remove all carbon from the rings and ring groves. Insert one ring into the cylinder. Push it down about Piston ring one inch from the top. See Figure 10.11. Measure the end gap with a feeler gauge and com- pare to the chart at the end of this chapter.
  • Page 96 T65 Series Vertical Shaft Engines Piston ring end Top ring NOTE: The piston ring end gaps need to be stag- gap stagger gered 90 apart. See Figure 10.14. Middle ring Oil ring Figure 10.14 Measure the distance between the ring and the ring land using a feeler gauge and compare the mea- surement to the chart at the end of this chapter.

  • Page 97: Connecting Rod Inspection

    Crankshaft, piston and connecting rod Connecting rod inspection Inspect the connecting rod for cracks or any signs of damage. Install the rod cap and tighten to a torque of 53 -62 in Measure at lbs (6 - 7 Nm) right angles Measure the inside diameter of the connecting rod and compare the measurements to those listed in the chart at the end of this chapter.

  • Page 98: Cylinder Inspection

    T65 Series Vertical Shaft Engines Cylinder inspection Clean and inspect the cylinder, inside and out. Measure the cylinder bore NOTE: If there is any sign of damage, especially cracked cooling fins, short block the engine. NOTE: Take two measurements of the cylinder bore 90 degrees apart at the top, bottom and mid- dle of the cylinder.

  • Page 99: Bearings

    Crankshaft, piston and connecting rod Bearings There are two bearings to inspect; a plain bearing in the sump and a plain bearing in the cylinder block. To inspect the bearings: Sump Oil Seal Remove the sump and cylinder block oil seals using a seal puller.

  • Page 100: Reassembly

    T65 Series Vertical Shaft Engines Reassembly Clean the cylinder Remove all gasket material from all mating surfaces. Clean the cylinder and sump. Oil seals Install a new oil seal in the cylinder block. Tecumseh seal driver Install a new seal in the sump. See Figure 10.22.
  • Page 101 Crankshaft, piston and connecting rod 5d. Tap the piston through the ring compressor into the cylinder using a wooden hammer handle. See Figure 10.25. Tap piston with hammer NOTE: Make sure the crankshaft journal is at Bottom handle Dead Center (BDC) to prevent damage from the connecting rod.
  • Page 102 T65 Series Vertical Shaft Engines Install the cam shaft by: Pre-lube the cam shaft with clean 10W-30 motor oil or engine assembly lube. Rotate the crankshaft until the timing mark points to the tappets. NOTE: A permanent marker can be used to high- light the timing marks for assembly.
  • Page 103 Crankshaft, piston and connecting rod Install the fuel tank by following the steps described in Chapter 4: Fuel systems and Governor. Install the carburetor by following the steps described in Chapter 3: Air Intake and Filters. Install the flywheel and module by following the steps described in Chapter 7: Ignition system. NOTE: If equipped, install the engine brake by following the steps described in the application’s service man- ual.

  • Page 104: Engine Specifications Chart

    T65 Series Vertical Shaft Engines Engine specifications chart New Min New Max Inch Metric Inch Metric Bore 2.559 65.005 2.600 65.015 Crankpin diameter 0.905 22.984 0.905 22.993 Connecting rod ID (crank side) 0.906 23.010 0.906 23.020 Connecting rod ID (piston side) 0.520...

  • Page 105: Chapter 11: Failure Analysis

    Failure Analysis CHAPTER 11: FAILURE ANALYSIS A properly maintained engine will provide years of service. Occasionally an engine will fail. An important part of working on engines is being able to recognize the root cause of engine failures. Was it something the customer did? Was it a manufacturing defect? Did the engine just wear out? All of these questions need to be answered.
  • Page 106 T65 Series Vertical Shaft Engines When particles enter the combustion chamber, the up and down motion of the piston grinds the parti- cles against the side of the cylinder walls and dam- ages the cylinder wall, piston and piston rings.

  • Page 107: Abrasive Ingestion

    Failure Analysis Because the oil suspends the particles, the engine components that are immersed in oil will show defi- nite signs of abrasive ingestion especially around the connecting rod and main bearing journals. See Figure 11.5. NOTE: Abrasives that are trapped in the oil will cause more wear to the lower portion of the combustion chamber than the upper portion.
  • Page 108 T65 Series Vertical Shaft Engines Insufficient lubrication The bearing surfaces in an engine are not smooth. The machining processes used to make the engine parts, leave little peaks and valleys that are only visible under a microscope. These peaks are called asperities. As the engine breaks in, the asperities break off leaving plateaus that become the bearing surface.
  • Page 109 This phenomenon is unique to MTD vertical shaft engines. If there is a clam shell pattern, similar to the one circled in Figure 11.9, the engine experi- enced a lack of lubrication failure.

  • Page 110: Insufficient Lubrication

    T65 Series Vertical Shaft Engines Engine Overspeed The MTD engine is designed for a maximum speed of 3300 RPM. When the governor is unable to control the engine rpm, the engine can accelerate past the safe maximum speed. When an engine runs beyond its designed speed, a few things happen: As the piston moves up and down in the cylinder, it builds momentum.
  • Page 111 Engine Overheat MTD engines are air cooled engines. Because of this, cleanliness of the engine is very important to the life of the engine. Dirt, grass and sludge all form an insulating layer on the engine. This will trap the heat in the engine and cause it to overheat.

  • Page 112: Engine Overspeed

    T65 Series Vertical Shaft Engines Mechanical Breakage/ Wear Sometimes an engine fails because a part breaks. There are generally three causes of a broken part, outside of the previously discussed engine failures. They are abuse, wear, and manufacturing defects. Bent blade A very common sign of an abused engine is a bent crankshaft.
  • Page 114 MTD Products Inc - Product Training and Education Department FORM NUMBER - 769-09624 12/2013...

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