Impossibly high compression results????????
#17
Sorry for bringing up a really old thread, I haven't been able to find much regarding this topic. I wanted to check compression on my 92 SC400 with 200k on the odometer. Will this compression pressure apply on mine?
From the repair manual, 95.
12. CHECK CYLINDER COMPRESSION PRESSURE
(a) Reconnect the negative (-) terminal cable to the battery.
(b) Insert a compression gauge into the spark plug hole.
(c) Fully open the throttle.
(d) While cranking the engine, measure the compression
pressure.
HINT: Always use a fully charged battery to obtain engine
speed of 250 rpm or more.
(e) Repeat steps (b) through (d) for each cylinder.
NOTICE: This measurement must be done in as short a
time as possible.
Compression pressure:
1,226 kPa (12.5 kgf/cm2, 178 psi) or more
Minimum pressure:
981 kPa (10.0 kgf/cm2, 142 psi)
Difference between each cylinder:
98 kPa (1.0 kgf/cm2, 14 psi) or less
(f) If the cylinder compression in one or more cylinders is low,
pour a small amount of engine oil into the cylinder through the
spark plug hole and repeat steps (b) through (d) for cylinders
with low compression.
• If adding oil helps the compression, it is likely that the
piston rings and/or cylinder bore are worn or damaged.
• If pressure stays low, a valve may be sticking or seating
is improper, or there may be leakage past the gasket.
(g) Disconnect the negative (-) terminal cable from the battery.
Notice it says 178psi or more. Doesn't say anything about a max.
If the car runs good, I wouldn't worry about it since you didn't find any indications of a problem.
BTW, fluid of any kind in the chambers could cause a high reading but you would have seen it with the scope.
KC
12. CHECK CYLINDER COMPRESSION PRESSURE
(a) Reconnect the negative (-) terminal cable to the battery.
(b) Insert a compression gauge into the spark plug hole.
(c) Fully open the throttle.
(d) While cranking the engine, measure the compression
pressure.
HINT: Always use a fully charged battery to obtain engine
speed of 250 rpm or more.
(e) Repeat steps (b) through (d) for each cylinder.
NOTICE: This measurement must be done in as short a
time as possible.
Compression pressure:
1,226 kPa (12.5 kgf/cm2, 178 psi) or more
Minimum pressure:
981 kPa (10.0 kgf/cm2, 142 psi)
Difference between each cylinder:
98 kPa (1.0 kgf/cm2, 14 psi) or less
(f) If the cylinder compression in one or more cylinders is low,
pour a small amount of engine oil into the cylinder through the
spark plug hole and repeat steps (b) through (d) for cylinders
with low compression.
• If adding oil helps the compression, it is likely that the
piston rings and/or cylinder bore are worn or damaged.
• If pressure stays low, a valve may be sticking or seating
is improper, or there may be leakage past the gasket.
(g) Disconnect the negative (-) terminal cable from the battery.
Notice it says 178psi or more. Doesn't say anything about a max.
If the car runs good, I wouldn't worry about it since you didn't find any indications of a problem.
BTW, fluid of any kind in the chambers could cause a high reading but you would have seen it with the scope.
KC
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