Dodge RAM TRUCK 1500 1995 Service Manual page 309

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COOLING SYSTEM SERVICE PROCEDURES 7 - 39
diesel engine is equipped with a one-way check valve
(jiggle pin). The check valve is used as a servicing
feature and will vent air when the system is being
filled. Water pressure (or flow) will hold the valve
closed. D u e to the use of this valve, t h e engine
must not be operating when refilling the cool­
ing system. Refer to Thermostat Operation—5.9L
Diesel Engine in the Thermostat section of this group
for more information.
(4) Fill coolant reserve/overflow tank to the FULL
mark.
(5) Start and operate engine until thermostat
opens. Upper radiator hose should be warm to touch.
(6) If necessary, add 50/50 water and antifreeze
mixture to the coolant reserve/overflow tank to main­
tain coolant level. This level should be between the
ADD and FULL marks. The level in the reserve/over­
flow tank may drop below the ADD mark after three
or four warm-up and cool-down cycles.
COOLING SYSTEM CLEANING/REVERSE FLUSHING
CLEANING
Drain cooling system and refill with water. Run en­
gine with radiator cap installed until upper radiator
hose is hot. Stop engine and drain water from sys­
tem. If water is dirty, fill system with water, run en­
gine and drain system. Repeat until water drains
clean.
MEVE^SE FLUSHING
Reverse flushing of cooling system is the forcing of
water through the cooling system. This is done using
air pressure in the opposite direction of normal cool­
ant flow. It is usually only necessary with very dirty
systems with evidence of partial plugging.
REVERSE FLUSHING RADIATOR
Disconnect radiator hoses from radiator inlet and
outlet. Attach a section of radiator hose to radiator
bottom outlet fitting and insert flushing gun. Con­
nect a water supply hose and air supply hose to
flushing gun.
CAUTION: Internal radiator pressure must not ex­
ceed 138 kPa (20 psi) as damage to radiator may re­
sult.
Allow radiator to fill with water. When radiator is
filled, apply air in short blasts. Allow radiator to re­
fill between blasts. Continue this reverse flushing
until clean water flows out through rear of radiator
cooling tube passages. Have radiator cleaned more
extensively by a radiator repair shop.
REVERSE FLUSHING ENGINE—EXCEPT
DIESEL
Drain cooling system. Remove thermostat housing
and thermostat. Install thermostat housing. Discon­
nect radiator upper hose from radiator and attach
flushing gun to hose. Disconnect radiator lower hose
from water pump and attach a lead-away hose to wa­
ter pump inlet fitting.
Connect water supply hose and air supply hose to
flushing gun. Allow engine to fill with water. When
engine is filled, apply air in short blasts, allowing
system to fill between air blasts. Continue until clean
water flows through the lead away hose.
Remove lead away hose, flushing gun, water supply
hose and air supply hose. Remove thermostat hous­
ing and install thermostat. Install thermostat hous­
ing with a replacement gasket. Refer to Thermostat
Replacement. Connect radiator hoses. Refill cooling
system with correct antifreeze/water mixture. Refer
to Refilling the Cooling System.
REVERSE FLUSHING ENGINE—DIESEL
(1) Drain the cooling system.
(2) Disconnect the upper hose from the radiator.
(3) Disconnect the radiator lower hose from the
water pump.
(4) Remove the heater core inlet hose from tube
(Fig. 55).
Fig. 55 Typical Reverse-flushing—5.9L Diesel
(5) Attach water supply hose to heater tube.
(6) Back-flush the engine until clean water exits
the water pump inlet.
CHEMICAL CLEANING
In some instances, use a radiator cleaner (Mopar
Radiator Kleen or equivalent) before flushing. This
will soften scale and other deposits and aid flushing
operation.
CAUTION: Follow manufacturers instructions when
using these products.