Dodge RAM TRUCK 1500 1995 Service Manual page 312

42
COOLING SYSTEM SERVICE PROCEDURES — — — — — BR
COOLANT
RESERVE/OVERFLOW
BOLTS (2) J948D-21
Fig. 59 Coolant Reserve/Overflow Tank—8.01 V-10
Engine
water. Rinse tank thoroughly before refilling cooling
system as described in the Coolant section of this
group.
TANK MBm&WAl—ALl EXCEPT 8.0L ¥-10
ENGINE
(1) Remove overflow hose from radiator.
(2) Unsnap the coolant reserve/overflow tank from
fan shroud. Lift straight up. The fan shroud is
equipped with T-shaped slots (Fig. 58) to attach the
tank. An alignment pin is located on the side of tank.
INSTALLATION!
(1) Snap the tank into the two T-slots and the
alignment pin on fan shroud.
(2) Connect overflow hose to radiator.
TANK REMOVAL—8.0L
V-1G
ENGINE
(1) Remove overflow hose from radiator.
(2) Remove three tank mounting bolts (Fig. 59)
and remove tank.
INSTALLATION •
(1) Position tank to inner fender.
(2) Install bolts and tighten to 6 N-m (50 in. lbs.)
torque.
(3) Connect overflow hose to radiator.
RADIATOR PRESSURE CAP
Radiators are equipped with a pressure cap, which
releases pressure at some point within a range of 97-
124 kPa (14-18 psi). The pressure relief point (in
pounds) is engraved on top of cap.
The cooling system will operate at pressures
slightly above atmospheric pressure. This results in a
higher coolant boiling point allowing increased radi­
ator cooling capacity. The cap (Fig. 60) contains a
spring-loaded pressure relief valve that opens when
system pressure reaches release range of 97-124 kPa
(14-18 psi).
Fig. 60 Radiator Pressure Cap and Filler Neck-
Typical
A vent valve in the center of cap allows a small
coolant flow through cap when coolant is below boil­
ing temperature. The valve is completely closed when
boiling point is reached. As the coolant cools, it con­
tracts and creates a vacuum in the cooling system.
This causes the vacuum valve to open and coolant in
the reserve/overflow tank to be drawn through its
connecting hose into radiator. If the vacuum valve is
stuck shut, the radiator hoses will collapse on cool-
down. Clean the vent valve (Fig. 60).
A rubber gasket seals radiator filler neck to pre­
vent leakage. This is done to keep system under
pressure. It also maintains vacuum during coolant
cool-down allowing coolant to return from reserve/
overflow tank.
RADIATOR CAP-TO-FILLER NECK SEAL-
PRESSURE RELIEF CHECK
The pressure cap upper gasket (seal) pressure re­
lief can be tested by removing overflow hose from ra­
diator 'filler neck nipple. Attach hose of pressure
tester tool 7700 (or equivalent) to nipple. It will be
necessary to disconnect hose from its adapter for
filler neck. Pump air into radiator. The pressure cap
upper gasket should relieve at 69-124 kPa (10-18 psi)
and hold pressure at a minimum of 55 kPa (8 psi).
WARNING: THE WARNING W O R D S —DO NOT
O P E N HOT-— ON RADIATOR P R E S S U R E CAP, A R E
A SAFETY PRECAUTION. W H E N HOT, P R E S S U R E
BUILDS U P IN COOLING S Y S T E M . TO P R E V E N T
SCALDING OR INJURY, RADIATOR CAP SHOULD
NOT B E REMOVED WHILE SYSTEM IS HOT AND/OR
UNDER P R E S S U R E .
Do not remove radiator cap at any time except for
the following purposes:
• Check and adjust antifreeze freeze point
• Refill system with new antifreeze
• Conducting service procedures
• Checking for vacuum leaks