Maintenance; Thermostat Operation; Thermostat Replacement; Checking New Thermostat - PREVOST H3-41 Maintenance Manual

FIGURE 14: CHARGE AIR COOLER HOSE CLAMPS (H3
SERIES SHOWN)
4.2.1

Maintenance

Since the constant-torque clamp automatically
adjusts to keep a consistent sealing pressure,
there is no need to torque hose clamps on a
regular basis. During vehicle operation and
shutdown, the screw tip will adjust according to
the temperature and pressure changes.
Checking for proper torque should be done
at room temperature.
5.

THERMOSTAT OPERATION

5.1

THERMOSTAT REPLACEMENT

17. Drain the cooling system.
18. Remove the bolts, the thermostat housing
and the thermostat. Carefully clean the
thermostat seat and all cylinder head-to-
thermostat housing mating surfaces.
FIGURE 15: VOLVO D13 THERMOSTAT HOUSING
19. Install the new thermostat. Make sure that the
rubber seal remains properly seated.
20. Position the thermostat housing to the
cylinder head, install the bolts and tighten.
21. Install the rubber radiator hose to the
thermostat housing. Position the clamp and
tighten to secure.
22. Fill the system with the recommended
coolant.
23. Start the engine, check for leaks and proper
operation. After shutdown, replenish fluids as
necessary.
5.2
A function check must be carried out before
installing a new thermostat.
NOTE
Check to be sure that the new thermostat
closes fully. This can be done by holding it up
to the light to check that there is no visible gap
at the opening point. If the thermostat does not
close properly, replace it.
1. Warm up water in a receptacle to 75°C
(167°F) and immerse the thermostat in the
water. Use a piece of wire attached to the
thermostat.
2. After at least 30 seconds, check that the
thermostat is still closed.
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).
PA1621 Maintenance Manual All Series
SECTION 05: COOLING SYSTEM
TORQUE: 15-21 lb-ft (20-28 Nm)

CHECKING NEW THERMOSTAT

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Section 05 revised Feb 2019
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