Filling Cooling System; Flushing; Cooling System Descalers - PREVOST H3-41 Maintenance Manual

SECTION 05B: X3 SERIES COOLING SYSTEM
8.

FILLING COOLING SYSTEM

If only the engine and related components were
drained, maintain the two heater line shutoff
valves in their closed position, then proceed as
follows:
1. Close radiator drain cock.
2. Open the shut-off valve on the coolant filter
mounting head.
3. Refill cooling system from the surge tank
filler cap inlet with the recommended
ethylene glycol-based antifreeze and water
solution of the required concentration using
the coolant extractor.
NOTE
Make sure the purge lines are properly
connected and not obstructed. The purge lines
(thermostat housing dome, radiator top tank,
transmission oil cooler or delivery line) are
required to ensure complete engine fill and
proper purging of air in the system.
NOTE
The coolant level should remain within two
inches of the surge tank filler neck.
4. Install the filler and pressure cap, then start
the engine and run it at fast idle until
reaching normal operating temperature.
Check for leaks.
NOTE
If for any reason, the coolant level drops
below the surge tank level probe, the Check
Engine warning light will illuminate.
5. Stop engine and allow cooling.
6. Open the two heater line shutoff valves,
check the coolant level in the surge tank,
and then add as required.
CAUTION
Never pour cold coolant into a hot engine.
The sudden change in temperature may crack
the cylinder head or block.
If the entire system has been drained, redo the
previous steps while maintaining the two heater
line shutoff valves in the "Open" position. With
engine running, activate the driver's and central
heating systems to permit coolant circulation.
Complete the procedure by bleeding the heater
16
PA1621 Maintenance Manual All Series
cores as explained in Section 22, under
"Bleeding Heating System".
9.

FLUSHING

If the cooling system is contaminated, flush the
cooling system as follows:
1. Drain the coolant from the engine.
2. Refill with clean water.
CAUTION
If the engine is hot, fill slowly to prevent rapid
cooling and distortion of the engine castings.
3. To thoroughly circulate the water, start and
run the engine for 15 minutes after the
thermostats have opened.
4. Fully drain system.
5. Refill with clean water and operate for 15
minutes after the thermostats have opened.
6. Stop engine and allow cooling.
7. Fully drain system.
Vehicles without coolant filters:
Fill with a 50/50-antifreeze/water solution
and add required inhibitors.
Vehicles with coolant filters:
Fill with a 50/50-antifreeze/water solution.
Replace coolant filter as per the Lubrication
and Servicing Schedule in section 24 if
required.
Dispose of spent fluids in an environmentally
responsible manner according to regulations in
effect in your area.
COOLING
(approximation)
Includes heating system: 26 US gal (99 liters)
9.1

COOLING SYSTEM DESCALERS

If the engine overheats and the water pump,
coolant level and thermostat operation have
been found to be satisfactory, it may be
necessary to flush and de-scale the cooling
system.
1. Drain the coolant from the engine.
2. Fill system with clean water.
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January 2017
SYSTEM CAPACITY