Nissan Sentra Service Manual: Compression pressure
Inspection
- Warm up the engine to full operating temperature.
- Release fuel pressure. Refer to EC-143, "Work Procedure".
- Remove ignition coil and spark plug from each cylinder. Refer to EM-46,
"Exploded View".
- Connect engine tachometer (not required in use of CONSULT).
- Install compression gauge (B) with an adapter (A) into spark
plug hole.

- Use the adapter whose pick up end inserted to spark plug hole
is smaller than 20 mm (0.79 in) in diameter. Otherwise, it may
be caught by cylinder head during removal.
(a) : 20 mm (0.79 in) or less

- With accelerator pedal fully depressed, turn ignition switch to “START”
for cranking. When the gauge
pointer stabilizes, read the compression pressure and the engine rpm.
Perform these steps to check each
cylinder.
Compression pressure : Refer to EM-118, "General
Specification".
CAUTION:
Always use a fully charged battery to obtain the specified engine
speed.
- If the engine speed is out of the specified range, check battery liquid
for proper gravity. Check the
engine speed again with normal battery gravity.
- If compression pressure is below minimum value, check valve clearances,
and parts associated with
combustion chamber (valve, valve seat, piston, piston ring, cylinder bore,
cylinder head, and cylinder
head gasket). After checking, measure compression pressure again.
- If some cylinder has low compression pressure, pour small amount of
engine oil into the spark plug hole
of the cylinder to recheck it for compression.
- If two adjacent cylinders have respectively low compression pressure and
their compression remains
low even after the addition of engine oil, cylinder head gaskets are
leaking. In such a case, replace cylinder
head gaskets.
- After inspection is completed, install removed parts.
- Start the engine, and check that the engine runs smoothly.
- Perform trouble diagnosis. If DTC appears, erase it. Refer to EC-55,
"Diagnosis Description".
Inspection and Adjustment
INSPECTION
Perform inspection after removal, installation or replacement of camshaft or
valve-related parts, or if there are
unusual engine conditions regarding valve cl ...
Other materials:
Engine Oils
Prolonged and repeated contact with used engine oil may cause skin cancer.
Try to avoid direct skin contact
with used oil.
If skin contact is made, wash thoroughly with soap or hand cleaner as soon as
possible.
HEALTH PROTECTION PRECAUTIONS
Avoid prolonged and repeated contact with oils ...
Starting the engine
Apply the parking brake.
CVT model:
Move the shift lever to P (Park) or N (Neutral).
P (Park) is recommended.
The shift lever cannot be moved out of
P (Park) and into any of the other gear
positions if the ignition switch is
turned to the OFF position or if the key
is removed from th ...
Spark plugs
Replacing spark plugs
WARNINGBe sure the engine and ignition switch are
off and that the parking brake is engaged
securely.
CAUTION
Be sure to use the correct socket to remove
the spark plugs. An incorrect socket
can damage the spark plugs.
Platinum-tipped spark plugs (ex ...
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