ROPA Maus 6 - Remarks of ROPA on the Coolant (General Information); Valve Clearance Adjustment

Maintenance and Service
Diesel engine
7.1.5.4 Remarks of ROPA on the coolant (general information)
Normally, coolant consists of water and corrosion protection/antifreeze agent. The cor-
rosion protection/antifreeze agents (ethylene glycol with corrosion inhibitors) have the
following tasks in the cooling system:
Sufficient corrosion and cavitation protection for all components of the cooling sys-
tem.
Lowering of the freezing point (frost protection).
Raising of the boiling point.
For reasons of corrosion protection, about 50 vol.-% corrosion protection/antifreeze
agents must be added to the cooling liquid, if the expected environmental tempera-
tures do not require even higher concentration. This concentration (50 vol.-%) offers
antifreeze protection up to about -37°C. A higher concentration is only sensible for
even lower environmental temperatures. Even in case of extremely low environmen-
tal temperatures, do not use more than 55 vol.-% of corrosion protection/antifreeze
agents, since the maximum frost protection is achieved then, and greater share in the
mixture reduces frost protection and worsens heat dissipation (55 vol.-% corresponds
to frost protection up to about -45°C). If these coolant regulations are not complied
with, then corrosion and damage to the cooling system are inevitable. Adding of cor-
rosion protection/antifreeze agents raises the boiling point. Increased pressure further
increases the boiling temperature. Both physics coherences are used in modern cool-
ing systems – the maximum coolant temperature is increased without increasing the
hazard of boiling. Corresponding to the higher temperature level, the cooling perfor-
mance increases.
7.1.6 Valve clearance adjustment
Checking or adjusting the valve clearance is required every second diesel engine
maintenance. This work may only be performed by people expressly authorized for
this work by Mercedes-Benz.
Valve clearance for cold diesel engine:
Inlet valves 0.30 mm +/- 0.05 mm
Outlet valves 0.60 mm +/- 0.05 mm
Engine brake The adjustment results in a valve clearance of
approx. 0.15 mm. The valve clearance of the
engine brake valve cannot be checked but it must
be adjusted.
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