Coolant; Coolant Level Verification; Coolant Level Sensor; Thawing Cooling System - PREVOST H3-41 Maintenance Manual

SECTION 05A: H3 SERIES COOLING SYSTEM
3. Now warm the water to 100°C (212°F). After
at least 30 seconds at the boiling point,
check that the thermostat has opened at
least 7mm (9/32in). If the thermostat has not
opened, it must be replaced. A good
thermostat starts to close at 95°C (203°F)
and is fully closed at approximately 85°C
(185°F).
6

COOLANT

6.1

COOLANT LEVEL VERIFICATION

Coolant level is correct when coolant reaches
the middle of the surge tank sight glass when
cold (ambient temperature). Fill the tank as
necessary with the same 50/50 water-antifreeze
mixture normally used. Do not mix two different
types of coolant.
FIGURE 14: SURGE TANK IN ENGINE COMPARTMENT
WARNING
Hot engine coolant is under high pressure.
Allow engine to cool down before adding
coolant.
6.2

COOLANT LEVEL SENSOR

This warning device consists of a fluid level
probe mounted on the surge tank. The probe
sends a signal to the engine control module to
indicate coolant level. If the coolant level drops
below the probe, the "Check Engine" light
flashes and a diagnostic code is registered (see
section 01" ENGINE").
14 PA1621 Maintenance Manual All Series | January 2017
CAUTION
Do not run engine with the "Check Engine"
light flashing.
The level probe is mounted on the front of the
surge tank.
6.3

THAWING COOLING SYSTEM

If the cooling system becomes frozen solid,
place the coach in a warm area until the ice is
completely thawed. Under no circumstances
should the engine be operated when the cooling
system is frozen, as it will result in engine
overheating due to insufficient coolant.
Once it is thawed, check engine, radiator and
related components for damage caused by the
expansion of frozen coolant fluid.
6.4 COOLANT RECOMMENDATIONS FOR
VOLVO D13 ENGINE
The coolant provides a medium for heat transfer
and controls the internal temperature of the
engine during operation. In an engine having
proper coolant flow, some of the combustion
heat is conveyed through the cylinder walls and
the cylinder head into the coolant. Without
adequate coolant, normal heat transfer cannot
take place within the engine, and engine
temperature rapidly rises.
To function properly, the cooling system must be
pressurized to prevent localized boiling of
coolant. The system must be kept clean and
leak-free. The filler and pressure caps must be
checked periodically for proper operation.
Always maintain cooling system at the proper
coolant level. Check daily, use recommended
extended life coolant (ELC) with 50/50 antifreeze
and deionized water mixture ratio. This ratio
should be used year-round to provide freeze and
boil-over protection as well as providing a stable
environment for seals and hoses.
When topping up coolant, use the same coolant
mixture type as the mixture already in the
cooling system. Do not mix two different types of
coolant.
Do not use antifreeze formulated for automobile
gasoline engines, these have a very high silicate
content that will clog the radiator and leave
unwanted deposits in the engine.