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03-oo-8
Engine-Service
03-oo-8
SERVICE PROCEDURES (Continued)
COMP RESSION P RESSURE LIMIT CHART (Cont'd)
Maximum
Minimum
Maximum
Minimum
PSI
PSI
PSI
PSI
1034 kPa
779 kPa
1241 kPa
931 kPa
(150 PSI)
( 1 1 3 PSI)
(18 PSI)
( 1 35 PSI)
1048kPa
786 kPa
1255 kPa
936 kPa
(152 PSI)
( 1 14 PSI)
( 1 82 PSI)
( 1 36 PSI)
1062 kPa
793 kPa
1 269 kPa
952 kPa
(154 PSI)
( 1 15 PSI)
( 1 84 PSI)
( 1 38 PSI)
1076 kPa
807 kPa
1282 kPa
965 kPa
(156 PSI)
( 1 1 7 PSI)
(186 PSI)
(140 PSI)
1089 kPa
814 kPa
1296 kPa
972 kPa
(158 PSI)
( 1 18 PSI)
( 1 88 PSI)
( 1 4 1 PSI)
1 103 kPa
827 kPa
1 310 kPa
75=982 kPa
( 160 PSI)
(120 PSI)
( 1 90 PSI)
( 142 PSI)
1 1 10 kPa
834kPa
1 324 kPa
993 kPa
(161 PSI)
( 1 2 1 PSI)
( 1 92 PSI)
(144 PSI)
If one or more cylinders reads low, squirt
approximately one tablespoon of clean engine oil
meeting Ford specification WSS-M2C 153-F on top of
the pistons (6108) in the low-reading cylinders.
Repeat compression pressure check on these
cylinders.
Compression Readings-Interpreting
1 .
If
compression improves considerably, piston
rings are faulty.
2.
If
compression does not improve, valves are
sticking or seating poorly.
3.
If
two adjacent cylinders indicate low
compression pressures and squirting oil on piston
does not increase compression, the head gasket
(6051 ) may be leaking between cylinders. Engine
oil and
I
or coolant in cylinders cou!d result from
this condition.
Use the Compression Pressure Limit Chart when
checking cylinder compression so that the lowest
reading number is 75 percent of the highest
reading.
Maximum
Minimum
Maximum
Minimum
PSI
PSI
PSI
PSI
1 448 kPa
1083 kPa
1 655 kPa
1 24 1 kPa
(2 10 PSI)
( 1 57 PSI)
(240 PSI)
(180 PSI)
1462 kPa
1089 kPa
1669 kPa
1 248 kPa
(2 1 2 PSI)
( 1 58 PSI)
(242 PSI)
(181 PSI)
1476 kPa
1 103 kPa
1682 kPa
1262 kPa
(2 1 4 PSI)
( 1 60 PSI)
(244 PSI)
( 1 83 PSI)
1 489 kPa
1 1 1 1 kPa
1 696 kPa
1 269 kPa
(2 16 PSI)
( 1 62 PSI)
(246 PSI)
(184 PSI)
1 503 kPa
1 124 kPa
1 7 1 0 kPa
1 282 kPa
(2 18 PSI)
( 1 63 PSI)
(248 PSI)
( 186 PSI)
1 5 1 7 kPa
11 38 kPa
1 724 kPa
1 293 kPa
(220 PSI)
( 1 65 PSI)
(250 PSI)
(187 PSI)
1 631 kPa
1 223.25 kPa
(222 PSI)
( 1 66 PSI)
Example Readings
If, after checking the compression pressures in all
cylinders, the highest reading obtained was 1 35 1 kPa
( 1 96 psi) and the lowest pressure reading was 1069
kPa ( 1 55 psi), the engine is within specification and
the compression is satisfactory.
Cylinder Leakage Detector
When a cylinder produces a low reading, the use of
Rotunda Pressurization Kit 0 1 4-Q0705 or equivalent
will be helpful in pinpointing the exact cause.
The leakage detector is inserted in the spark plug
hole, the piston (6 1 08) is brought up to dead center on
the compression stroke and compressed air is
admitted.
Once the combustion chamber is pressurized, a
special gauge will read the percentage of leakage.
Leakage exceeding 20 percent is excessive.
1997 Thunderbird, Cougar July 1996