Compression Pressure Check; Engine Timing Adjustment - Yale GDP16-20AF Maintenance Manual

Engine Timing Adjustment

1. Remove spark plugs from cylinder head. Discon-
nect high tension wire at ignition coil. See Fig-
ure 53.
2. Install compression gauge in No. 1 cylinder. Make
sure gauge has minimum range of 1725 kPa
(250 psi).
3. Use starter to crank engine at least six revolutions.
Check pressure reading and release pressure. Re-
peat test again and make note of highest pressure.
Do this test for each cylinder.
Standard pressure reading is 1130 kPa (164 psi).
Minimum reading is 793 kPa (115 psi).
4. If the readings are lower than minimum reading,
there is a problem with the valves, piston rings, or
cylinder head gasket. Do the following tests to find
the problem:
a. Add approximately 30 ml (1.0 oz) of engine oil
to each cylinder at spark plug hole.
b. Crank engine approximately 10 revolutions to
distribute oil.
c. Install compression gauge and do same tests
as described in Step 3.
See Ignition System Check and Adjustment in the sec-
tion Mazda FE and F2 Gasoline/LPG Engines 2200
YRM 524 for the adjustment procedure for engine tim-
ing.
The correct timing for the GP/GLP/GDP16-20AF/BF
(GP/GLP/GDP030-040AF/BF),
and GLP/GDP16-20AF
units is as follows:
• Gasoline Engine = 0 BTDC @ 725 ±25 rpm (white
mark)
24

Compression Pressure Check

Engine Timing Adjustment
GC/GLC030-040AF,
(GP/GLP/GDP030-040AF)
• If pressure reading increases to normal read-
ing, low pressure was caused by worn or
damaged piston rings. Cylinder bore may
also be damaged.
• If pressure reading does not increase, low
pressure was caused by worn valves, valve
seats, or valve guides.
• If low pressure readings are in two cylinders
next to each other, cylinder head may be
leaking.
1. ADAPTER
Figure 53. Compression Pressure Check
• LPG Engine = 8 BTDC @ 725 ±25 rpm
The correct timing for the GC/GLC040-065TF/RF
and GP/GLP/GDP2.0-3.0RF/TF (GP/GLP/GDP040-
060RG/TG/ZG) units is as follows:
• Gasoline Engine = 0 BTDC @ 725 ±25 rpm (white
mark)
• LPG Engine = 9 BTDC @ 725 ±25 rpm (red mark)
600 YRM 496