1. Small engine maintenance and repair

2. lesson Objectives:
Identify tools needed for engine maintenance and repair orally with 100% accuracy.
Demonstrate the basic maintenance procedures required for small engines in the lab with 95% accuracy.
Explain the procedures for repairing the systems of a small engine on a written quiz with 90% accuracy.
Establish troubleshooting techniques using sequential procedure in the lab with 95% accuracy.

3. Mystery Tools? Have you ever seen any of these before? What are they?
Are they the same?
Can you guess what the function of these tools might provide?

4. Reasons to Learn
Why is it important to be able to identify tools needed for engine maintenance and repair?
Why is it important to be able to demonstrate the basic maintenance procedures required for small engines?
Why is it important to be able to explain the procedures for repairing the systems of a small engine?
Why is it important to be able to establish troubleshooting techniques using sequential procedure?

5. Questions to answer
What do we need to know in order to be able to identify tools needed for engine maintenance and repair?
What do we need to know in order to be able to demonstrate the basic maintenance procedures required for small engines?
What do we need to know to be able to explain the procedures for repairing the systems of a small engine?
What do we need to know to be able to establish troubleshooting techniques using sequential procedure?

6. Tools Basic Hand Tools: Standard wrenches sizes ¼ through 1 in.
Metric wrenches sizes 6 through 24
Needle nose pliers
Locking jaw pliers
Standard and metric hex wrenches
Phillips head screw drivers
Standard screw drivers
Ball peen hammer
Chisels
Punches

7. tools Specialty Tools: Flywheel wrench or Strap wrench Flywheel puller
Three jaw puller
Torque wrench
Micrometer
Telescoping gauge
Compression gauge
Spark tester
Ring expander
Ring compressor
Valve grinding tool
Cylinder hone
Spark plug gaper
Spring compressor
Pick set
Magnetic pickup tool

8. Demonstrating basic maintenance procedures
Read and follow all service publication instructions! Service manuals are a student’s best friend. Read! Read! Read! When in doubt read again.

9. Shop safety and small engines
Safety glasses must be worn at all times.
Handle gasoline outdoors if possible.
Keep hands and feet away from all moving parts during operation.
Disconnect the spark plug lead when making adjustment to prevent accidental start-up.
Keep all ignition sources away from the work area.
Never disengage any of the safety equipment or devices.
Stop engine and allow it to cool before refueling.

10. Shop safety and small engines
Keep all shields in place.
Only start and run engines where ventilation is adequate, preferably outdoors.
Do not operate engines above the specified speed.
Never pour gasoline or oil on the ground or down a drain, dispose of it in the correct container to be recycled.
Never overload engines or force equipment beyond it the designed capacity.
Never use gasoline as a solvent to clean parts.

11. Basic maintenance
Air filters can become clogged over time and should be changed (Never! Blow out an air filter with compressed air!) This can damage the filter and cause immediate engine damage.

12. Basic maintenance
Fuel filters can also become clogged over time and should be changed (Never! Blow out a fuel filter with compressed air!) This can damage the filter and cause immediate engine damage.
OLD
NEW

13. Basic maintenance
Tanks & valves can also become clogged over time however these items can be clean with solvent and blown out with low volume compressed air.

14. Basic maintenance
Carburetors can be adjusted although it is rarely necessary. Commonly small engines are factory preset and will not acquire adjustment. However, in the case that adjustment is necessary there are usually 3 adjustment points on a carburetor.

15. Basic maintenance
Main mixture adjustment screw- this screw adjusts the fuel to air mixture ratio by allowing more or less liquid fuel into the carburetor to mix with air to be combusted.
Idle mixture adjustment screw- this screw adjusts the idle air to fuel mixture.
Idle Speed adjustment screw- this screw adjusts the idle speed by changing the position of the throttle valve. 3. 2. 1.

16. Basic maintenance
Lubrication is very important it is necessary to deduce whether or not the engine has a pressurized lube system or not. This is a simple deduction.
Pressurized systems- utilize the use of an oil filter
Non-pressurized- does not utilize an oil filter.

17. Basic maintenance
Different engines require different oils of different viscosities.
Viscosity- is the thickness of the oil
Many non-pressurized engines call for non-detergent, single viscosity oils such as ND30
Many pressurized engines call for multi-viscosity oils such as 10w30
Multi-viscosity- is the thickness of the oil at different operating temperatures
Dip sticks must also be located and checked regularly according to service manual.

18. Basic maintenance
Cooling system- usually can be blown out with compressed air in air cooled and liquid cooled applications. May require coolant checks for adequate level and ratio in liquid cooled applications.
Air Cooled
Liquid Cooled

19. Basic maintenance
Electrical system- somewhat maintenance free with the exception of the spark plug and a few switches which requires replacement at implied intervals.

20. Repair procedure
KIS- Keep It Simple, Always check the easy things first. If an engine suddenly stops running, chances are the solution is an easy fix. As we learned in the previous chapter the principles of operation must happen sequentially for an engine to run. If one or more of these steps are incomplete the engine will fail to run.

21. Micrometer
Micrometer- measuring tool used to check components for wear

22. Telescoping Gauge
Telescoping Gauge- t-shaped tool used to measure cylinder wear

23. Torque wrench
Torque wrench- used to tighten fasteners to specific tolerances
Foot-lbs & inch-lbs

24. Ring-compressor
Ring-compressor- used to compress piston rings for piston installation

25. Flywheel wrench or strap wrench
Flywheel wrench or strap wrench- used to hold flywheel to remove nut

26. Flywheel puller
Flywheel puller- used to pull stuck flywheels

27. Spark tester
Spark tester- used to safely test spark

28. Spring compressor
Spring compressor- used to compress valve springs

29. Feeler gauge
Feeler gauge- used to check clearances

30. Valve grinder
Valve grinder- used to grind and lap valves

31. troubleshooting
Check for fuel. Make sure there is plenty of fuel in the tank and that the fuel is fresh. Remove the fuel line from the carburetor to be sure that the fuel flows freely from the tank, through the line and into the carburetor. If it doesn’t you must find the blockage and remove it.

32. troubleshooting
Check for spark. If the engine cranks but will not start it may not be firing. Use a spark tester to identify spark. Lack of spark may be a faulty plug, armature coil, breaker points, or ground switch

33. troubleshooting
After cranking several times and no start remove the spark plug and examine it.
Dry- you have a fuel delivery issue inside the carburetor.
Extremely wet- the carburetor is flooding the engine.
dry
wet

34. Troubleshooting Spark plugs
Black- carburetor that is running too rich (too much gas), or excessive idling on some engines
White- Carburetor air/fuel mixture is too lean (too much air)

35. troubleshooting
If you have spark and fuel but the engine fails to start or sounds like it is backfiring or is hard to crank, the flywheel key could be to blame.
A flywheel key is designed to take the brunt of a blow if the engine is stopped abruptly.
If the key is sheared the timing will be affected because it adjusts the position of the permanent magnet found in the flywheel
This adjustment causes the spark plug to fire at the wrong time hence the backfiring or no start condition.

36. troubleshooting
When all of the above methods have been exerted and found to be ineffective, you should run a cylinder compression test. Compression test results will act as a guide and let you know which route to take.
If the compression tests well then the prior steps may need to be repeated because you may have missed something simple.
If the compression tests badly then the repair may have just gotten more costly.

37. troubleshooting Engines lose compression for three primary reasons:
Wear and tear
Blown head gasket
Off timing
In no-tolerance engines if timing is off the piston could come in contact with the valves and cause serious component damage.

38. summary
What do we need to know in order to be able to identify tools needed for engine maintenance and repair?
Basic hand tools and specialty tools
What do we need to know in order to be able to demonstrate the basic maintenance procedures required for small engines?
Read and follow all service publication instructions!
Service manuals are a student’s best friend. Read! Read! Read!
When in doubt read again. Shop safety and small engines, we must also be concerned with the basic maintenance items: filters, lubes, dipsticks, etc.

39. summary
What do we need to know to be able to explain the procedures for repairing the systems of a small engine?
KIS- Keep It Simple, Always check the easy things first. If an engine suddenly stops running, chances are the solution is an easy fix.
We must know how to use specialty tools like:
• Micrometer- measuring tool used to check components for wear
• Telescoping Gauge- t-shaped tool used to measure cylinder wear
• Plastigage- threadlike material used to measure connecting rod bearing clearance
• Torque wrench- used to tighten fasteners to specific tolerances
• Ring-compressor- used to compress piston rings for piston installation
• Flywheel wrench or strap wrench- used to hold flywheel to remove nut
• Flywheel puller- used to pull stuck flywheels
• Spark tester- used to safely test spark
• Spring compressor- used to compress valve springs
• Feeler gauge- used to check clearances
• Valve grinder- used to grind and lap valves

40. summary
What do we need to know to be able to establish troubleshooting techniques using sequential procedure?
1. Check for fuel.
2. Check for spark.
3. Check for compression.
4. Do not disassemble engine unless absolutely necessary!