Small Gas Engines
Small Gas Engine
Inspection,
Measurement,
and Cleaning
User’s Guide
Introduction
This video explains the procedures used to properly inspect, clean, and service components
before reassembling a small gas engine. If engine parts are not cleaned and serviced correctly,
a small engine can self-destruct in a matter of seconds after the initial start-up.
The program stresses the importance of detailed inspection and accurate measurement of
part wear during an engine rebuild. It also demonstrates how to use the necessary instruments when measuring for such things as cylinder bore wear, piston wear, cylinder head
warpage, and other critical part measurements. To successfully rebuild a small gas engine, you
not only have to understand its construction and operating principles, you also must know
the proper procedures used to clean, inspect, and service engine components. This program
explains those procedures and supplies viewers with additional information needed to prepare
an engine for reassembly.
Student Objectives
After viewing this video, you will be able to:
• Explain the safety rules to follow when preparing small engine parts for engine reassembly.
• List several of the measuring devices used during a small gas engine rebuild.
• Properly clean and inspect a small engine’s cylinder block.
• Check for cylinder bore wear in a small engine’s cylinder block.
• Describe how to deglaze a cylinder on a small gas engine.
• Inspect the four critical areas of a small engine’s piston for damage or wear.
• Check the condition of a small engine’s connecting rod.
• Describe how to check the condition of the oil pump on certain small gas engines.
• Inspect and measure a small engine’s crankshaft for wear.
• Explain how to service a small engine’s valve train.
To The Instructor
This video is organized into major sections or topics. Each section covers one major segment
of the subject. Graphic breaks are given between each section so that you can stop the video
for class discussion, to answer critical questions, to ask questions, or perform in-class demonstrations with actual components or parts. The program’s format is arranged to be flexible.
View it full-length, or use it as a supplement for lectures or demonstrations. It can also be
used for self-paced individualized instruction. You can watch a portion of the program each
day, or present the complete video, depending on your curriculum requirements.
2
The program is designed to simplify the complex. Concise wording and carefully selected
graphics are used to provide maximum learning in minimum time. Close-up shots of components and service procedures are used to make every second of viewing instructional, as if
each student were standing right behind you, watching over your shoulder while you were
working or giving a demonstration. Our technical visual images are designed to match the
audio so that every scene has maximum educational value. Computer animation is used to
explain difficult principles or techniques. Students seem to enjoy the images that show how
parts work, how they fit together, and how they vary in design.
Copyright © 1993 Meridian Education Corporation®
Quiz Answer Key
1) b
2) a
3) c
4) c
5) a
6) d
7) a
8) b
9) d
10) b
11) c
12) b
13) b
14) c
15) b
Use your own judgment to evaluate the technical terms, discussion topics, and short answers.
Technical Terms
Write definitions for the following terms. Use a textbook or review the video, if needed.
cylinder block
crankcase cover
cylinder bore
ring ridge
combustion chamber
cylinder head
bearing bores
connecting rod
connecting rod big end
connecting rod small end
valve seats
valve guides
valve stem
valve springs
valve keepers
valve retainers
valve stem tip
valve face
interference angle
cylinder deglazing
rigid hone
engine crankcase
flex hone
cylinder out-of-roundness
cylinder taper
cylinder head ports
engine cooling fins
cylinder bore wear
dial bore gauge
micrometer
crankcase seals
cylinder block bearings
cylinder head gasket
surface
hole gauge
outside micrometer
knurled
straightedge
feeler gauge
piston skirt
piston boss
piston head
piston pin
piston rings
piston ring expander
tool
piston ring groove
engine crankshaft
crankshaft journals
rocker arms
push rods
lifters
valve seat angle
valve grinding
machine
valve face angle
valve grinding
compound
Discussion Topics
Here are a few topics that might be used for a class discussion.
1. Why should you remove any dirt or grime from a small engine cylinder block before
inspecting it for problems?
2. Describe how to measure cylinder bore wear in a small gas engine.
3. Why is it important to locate any worn bearings during a small engine rebuild?
4. Describe how to properly deglaze a small engine cylinder.
5. Explain the procedures used to clean a small engine cylinder head.
6. What should you do if you find any problems with a small engine’s connecting rod?
7. What safety rules should be followed when using a wire wheel to remove carbon deposits
from a small engine’s valves?
3
8. Describe the basic procedures used to perform a valve job on a small gas engine.
Quiz
Choose the most correct answer after reading the statement.
1. If a small engine’s cylinder block has a ring ridge, the __________ is probably badly worn.
a. crankshaft
b. cylinder
c. camshaft
d. head
2. If the valve ___________ are located in the block, you should inspect them closely for
burning, physical damage, or wear.
a. seats
b. keepers
c. springs
d. retainers
3. If a bearing is machined as part of the crankcase, it is probably better to buy a new
________ than to try to repair the bearing surface.
a. bearing
b. seal
c. crankcase
d. cylinder
4. Deglazing is sometimes recommended by the engine manufacturer for cast iron cylinders
and aluminum cylinders that are used with _______________ rings.
a. carbon
b. magnesium
c. chrome
d. solid
5. A ___________ hone should be used to remove a small amount of taper from a small
engine’s cylinder.
a. rigid
b. carbon
c. flex
d. brush
6. A ____________________ is normally used to remove any heavy carbon deposits inside the
engine’s combustion chamber.
a. grinder
b. driver
c. cutter
d. scraper
4
7. When cleaning a small engine’s cylinder head, you should wipe away any debris from the
cooling ____________ to prevent engine _______________.
a. fins, overheating
b. ports, stalling
c. vents, knocking
d. none of the above
8. If a small engine’s valve guides are worn beyond specs, they should be _____ or ______.
a. ground, honed
b. knurled, replaced
c. honed, replaced
d. knurled, ground
9. Which of the following set of devices are used to measure cylinder head warpage?
a. dial bore gauge, feeler gauge
b. micrometer, dial bore gauge
c. straightedge, hole gauge
d. feeler gauge, straightedge
10. Piston ________ diameter minus piston pin diameter equals piston pin clearance.
a. rod
b. bore
c. skirt
d. head
11. When inspecting the condition of a small engine’s ________, always check the snout
threads and journals for damage.
a. camshaft
b. lifters
c. crankshaft
d. governor
12. If a small engine’s camshaft is replaced, you should also install new ________________.
a. valves
b. lifters
c. keepers
d. retainers
13. When inspecting the condition of a small engine’s rocker arms, it is important that you
check where they contact the ______________________ and the push rods.
a. keepers
b. valves
c. retainers
d. springs
14. A valve grinding machine uses a large grinding ________ to remachine the valve _______.
a. plate, head
b. shaft, guide
c. stone, face
d. pad, guide
15. Valve grinding ______ can be used to check a valve job performed on a small gas engine.
a. pads
b. compound
c. oil
d. cutters
5
Short Answers
Briefly answer the following questions in your own words.
1. What should you look for when inspecting a small engine’s cylinder block for problems?
2. Why is it important to use caution when using a scraper to remove gasket material from
a small engine’s cylinder block and crankcase cover?
3. Describe the basic purpose of a flex hone.
4. Why is it essential to properly clean a small engine’s cylinder after honing?
5. Describe how to check a small gas engine for valve guide wear.
6. Explain how to check a small engine’s piston for wear.
7. How do you remove the rings from a small engine’s piston?
8. What should be done if a small engine’s valve stems are worn beyond specs?
9. How can a worn cam lobe affect the performance of a small gas engine?
10. What type of problems should you look for when inspecting a small engine’s push rods
for damage?
6
atio
form
n
i
For
her programs visit ou
n on ot
rw
ebs
ite
at
www.meridianeducation.com
2572 Brunswick Pike, Lawrenceville, NJ 08648
Toll Free: 1 800/727-5507
Fax: 1 888/340-5507
26298