Bomag BW 156 D-3, Service Manual

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Service Training
BW 156/177 D-3/PD-3
BW 178/179 D-3/PD-3
- DTr 17 -
Fig. F16:
Checking the thermostat valve
If the hydraulic oil heats up to a too high temperature it will loose its lubrication properties, which may
cause damage to important components in the hydraulic system.
In case of a too high hydraulic oil temperature shut the engine down immediately, let the system cool
down and perform trouble shooting. Do not start to operate the machine unless the fault has been
corrected.
First check the function of the thermostat valve. Up to a temperature of 60°C all leak oil, flushing and
return flow quantities flow directly back into the tank. At 60°C the thermostat valve should start to open
and guide the hydraulic oil through the hydraulic oil cooler back to the tank.
• Feel with your hand if the hose to the hydraulic oil cooler starts to become warm after a hydraulic oil
temperature of 60°C is reached.
• If the thermostat valve does not open it must be replaced immediately.