Yanmar 1GM User Manual page 20

GENERAL INFORMATION
13
Ha mme rs
The correc t hammer (F igure 29) is necessary for many
types of repairs. Usc only a hammer with a face (or head)
made ofrubber or plastic or the soft-faced type filled with
leadshot. Never usc a metal-faced hammer on engine or
jet pump parts, as severe damage wi ll result. Ba ll-peen or
machinist's hammers are required if striking ano ther too l,
such as a punch or impact driver. When striking a hammer
against a punch, cold chisel or similar tool, the face ofthe
hammer should be at least 1/2 in. larger than the head of
the tool. Ifi t is necessary to strike hard against a steel part
without damaging it, use a brass hammer. A brass hammer
can be used because brass will give when striking a harde r
object.
_ When _ using hammers, note the following:
l. Always wear safety glasses.
2. Inspect hammers for damaged or broken parts. Repair
or replace the hammer as required. Do not use a hammer
with a taped handle.
3. Always wipe oil or grease off the hammer before using
it.
4. The head of the hammer should always strike the ob-
ject squarely. Do not use the side of the hammer or the
handle to strike an objec t.
5. Always use the correct hammer for the job.
PRECIS ION MEASURING TO OL S
Measurement is an important part of service. When per-
forming
many of the service procedures in this manual, a
number of measurements will be required. These include
basic checks, such as engine compression and spark plug
gap. Measurements will be required to determine the con-
dition of the piston and cylinder bore, crankshaft runout
and so on. When making these measurements, the degree
of accuracy will dictate which tool is required. Precision
measuring tools arc expens ive. If these tools are not avail-
able, it may be more worthwhile to have the checks made
at a dealer. The following is a description ofthe measuring
tools requ ired during engine and transmission overhaul.
Feeler Ga uge
A feeler gauge (Figure 30) is made ofa piece ofa flat or
round hardened steel of a specified thickness. Wire
gauges are used to measure spark plug gap. Flat gauges
arc used for all other measurements.
I