Hydraulic Valve Tappets - Jeep 1979 CJ-5 Technical & Service Manual

11=10
ENGINES
Hydraulic Valve Tappets
The hydraulic valve tappet consists of tappet body,
plunger, plunger return spring, check valve assembly
metering disc, plunger cap and lockring (fig. 1B-15).
The tappet operates in a guide bore which intersects
with the main oil gallery.
4 2 8 1 1
Fig. 11-11 Ky Irialli Tcppsf Cwpiiiits
The operating cycle of the hydraulic tappet begins
when the tappet is on the heel of the cam lobe (engine
valve closed). A groove in the tappet body aligns with
the tappet oil gallery, admitting pressurized oil into the
tappet (fig. 1B-16). A hole and groove arrangement ad-
mits the oil to the inside of the plunger. Oil is forced past
the plunger check valve and fills the chamber between
the plunger and tappet body. When the chamber is full,
additional oil in the plunger body unseats the metering
disc, and a spurt of oil flows up the pushrod to lubricate
the rocker assembly. These events all take place while
the tappet is on the heel of the cam lobe. As the cam
turns, the lobe begins exerting force on the tappet body.
This force is transmitted by the trapped oil in the tappet
chamber to the plunger and finally to the pushrod and
rocker assembly. The engine valve opens. While the
valve is open, the trapped oil is subjected to considerable
pressure and some of it escapes between the plunger and
the tappet body (leak-down). The cycle is completed as
the cam lobe rotates back to the starting position and
another charging cycle begins. In this way, zero valve
lash is maintained.
H O L L O W
P U S H R O D
C H A R G I N G CYCLE L E A K - D O W N
CYCLE
8 0 4 4 3
Fig. 1 B-16
Hydraulic Tippet Operation
Removal
(1) Drain cooling system.
(2) Remove cylinder head cover and gasket.
(3) Remove rocker arms and bridged pivot assem-
blies. Remove two capscrews at each bridged pivot. Al-
ternately loosen each capscrew, one turn at a time, to
avoid damaging bridge.
(4) Remove push rods.
N O T E : Retain push rods in the same order as removed.
(5) Remove cylinder head and gasket.
(6) Remove tappets through push rod openings of
block with Hydraulic Valve Tappet Remover and In-
staller Tool J-21884 (fig. 1B-17).
Cleailig
and Inspection
N O T E : Retain tappet components in the same order as
removed.
(1) Release lockring and remove plunger cap, mete-
ring disc, plunger and plunger return spring from tappet
body.
(2) Clean components of hydraulic tappet assembly
in cleaning solvent to remove all varnish or gum
deposits.
(3) Check for signs of scuffing on side and face of
tappet body.