HYDRAULIC TAPPETS
DESCRIPTION
Before disassembling any part of the engine to cor-
rect tappet noise, check the oil pressure. If vehicle
has no oil pressure gauge, install a reliable gauge at
the pressure sending unit. The pressure should be 50
psi at 3000 RPM.
Check the oil level after the engine reaches normal
operating temperature. Allow 5 minutes to stabilize
oil level, check dipstick. The oil level in the pan
should never be above the FULL mark or below the
ADD OIL mark on dipstick. Either of these 2 condi-
tions could be responsible for noisy tappets:
OIL LEVEL HIGH
If oil level is above the FULL mark, it is possible
for the connecting rods to dip into the oil. With the
engine running, this condition could create foam in
the oil pan. Foam in oil pan would be fed to the
hydraulic tappets by the oil pump causing them to
lose length and allow valves to seat noisily.
OIL LEVEL LOW
Low oil level may allow oil pump to take in air.
When air is fed to the tappets, they lose length which
allows valves to seat noisily. Any leaks on intake side
of oil pump through which air can be drawn will cre-
ate the same tappet action. Check the lubrication
system from the intake strainer to the pump cover,
including the relief valve retainer cap. When tappet
noise is due to aeration, it may be intermittent or
constant, and usually more than 1 tappet will be
noisy. When oil level and leaks have been corrected,
operate the engine at fast idle. Run engine for a suf-
ficient time to allow all of the air inside the tappets
to be bled out.
Displacement . . . . . . . . . . . . . . . . . . . 3.1L (3125cc)
Bore . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92.00 mm
Stroke . . . . . . . . . . . . . . . . . . . . . . . . . . . 94.00 mm
Compression Ratio . . . . . . . . . . . . . . . . . . . . . . 21:1
Vacuum at idle . . . . . . . . . 600 mm/Hg (23.6 In/Hg)
Belt Tension . . . . . . 400/500N Automatic Tensioner
Thermostat Opening . . . . . . . . . . . . . . . 80°C
6 2°C
Generator Rating . . . . . . . . . . . . . . . . . Denso 130A
Cooling System Capacity . . . . . . . . . . . . . . 9.5 Liter
P/S Capacity . . . . . . . . . . . . . . . . . . . . . . 0.75 Liter
Engine Oil Capacity . . . . . 7.5 Liter w/filter change
Timing System . . Pushrod operated overhead valves,
with gear-driven camshaft in crankcase.
Air Intake . . . . . . . . . . . . . . . . . . . . . . . . Dry filter.
Fuel feed . . . . Vane pump incorporated in injection
pump.
Fuel System . . . . . . . . . . . . . Indirect fuel injection
(precombustion chamber).
Combustion Cycle . . . . . . . . . . . . . . . . . . . 4 stroke.
Cooling System . . . . . . . . . . . . . . . . . Water cooling.
Injection Pump . . . . . . Rotary pump with electronic
management.
Lubrication . . Pressure lubrication by rotary pump,
full-flow filtration.
Engine Rotation . . . . . . . . . Clockwise viewed from
front cover.
Engine Description
9 - 2
ENGINE
WJ
DESCRIPTION AND OPERATION (Continued)
2000 JEEP GRAND CHEROKEE