Cooling And Heating System - Mercedes-Benz OM 904 LA Operating Instructions Manual

correct concentration of 50% antifreeze/
corrosion inhibitor by volume in the coolant
provides antifreeze protection down to
Ò37 †. If a lower level of antifreeze protec-
tion is indicated, correct the mixture ratio.
! If the concentration of antifreeze/corro-
sion inhibitor is too low, there is a risk of
engine damage as a result of corrosion/
cavitation in the cooling system.
Avoid concentrations greater than
55% by volume corrosion inhibitor/antifreeze
agent. Otherwise, the maximum antifreeze
protection down to Ò45 † will not be attained.
Heat dissipation and antifreeze protection
deteriorate at higher concentrations.
X
To check the coolant level: the cooling
system is filled correctly if the coolant is
level with the mark in the filler neck.
Cooling and heating system – condi-
tion check of radiator, lines and hoses
Special tool: pressure tester tool
X
Heating systems: open all control valves
and shutoff valves for the heating system.
X
Remove the coolant expansion tank cap.
X
Check the coolant level and top up if nec-
essary.
X
Check/correct the coolant antifreeze pro-
tection content.
X
Rub dry the inside of coolant filler
neck ; with a lint-free cloth.
X
Mount pressure tester tool : on the filler
neck of the coolant expansion tank.
X
Connect the compressed-air hose with tyre
inflation connection to pressure tester
tool : and set it to a test pressure of
1.0 bar.
The test pressure should correspond to the
value at which the cooling system pressure
relief valve opens. The release pressure can
be determined from the value on the cap or
pressure relief valve.
Example: code 100 = 1.0 bar excess pres-
sure.
X
After about 5 - 10 minutes, read the man-
ometer on tester : to check for pressure
loss. After 5 - 10 minutes, there must be no
drop in pressure detected on the manom-
eter. Do not exceed the test pressure and
the test time, as this may damage the cool-
ing and heating system.
If the cooling system/heating system is
leaking, this will become apparent due to a
drop in pressure, indicated by the manom-
eter on tester :.
X
If there is a loss of pressure in the cooling
system leading to visible loss of coolant,
have the leak in the cooling or heating sys-
tem repaired.
X
If there is a pressure drop with no visible
loss of coolant: have the cause identified
and immediately rectified by a qualified
specialist workshop.
X
Release the pressure using pressure tester
tool : and remove pressure tester
tool : from the coolant expansion tank
filler neck.
X
Check the coolant level and correct if nec-
essary.
X
Replace coolant expansion tank cap and
tighten it.
Work schedules
Z
75