Cooling System
11---1
11. COOLING SYSTEM
A. Quality requirements of coolant
The coolant used must meet the standards ASTM D 3306 or
BS 6580:1992.
--- Mixing proportion should be 40---60 % of ethylene/propy-
lene---glycol based coolant and the rest water. The best ratio
is 50/50 %.
--- In warm climates the 30 % mixture ratio gives enough good
protection against corrosion.
--- Water used should be clean and soft water i.e. that it does
not include metals and their salts.
--- Check the coolant frost resistance every now and then.
Change the coolant every other year.
Note!
Never use only water as coolant!
B. Thermostat
645---engines have two separate thermostats. The smaller,
single---acting thermostat opens at 79
˚
C and the other,
double---acting type, at 83
˚
C. In 645---engines there are no
separate winter thermostats.
To remove
1. Drain the cooling system so that the coolant level is below
the thermostats position and disconnect the top hose from
the water outlet cover.
2. Remove the outlet cover and the thermostats. Clean the
sealing surfaces.
Check the function of the thermostat as follows:
--- Lower the thermostat into a vessel of boiling water so that
the thermostat does not touch the sides or bottom.
--- Opening must begin under 20 seconds.
--- The thermostat must be fully open under 50 seconds.
Stroke, see specifications.
To replace
411--- 1
67,5
62,0
1 Put the thermostats in position in the housing. Fit a new
gasket and the outlet cover. For guiding you can use M8 studs
(2 pcs). Observe the plate (if mounted) that comes on top of
the smaller thermostat. Fit the gasket so that the bigger hole
is on the same side as the plate.
2. Connect the top hose and fill the cooling system.