MTU 12 V 4000 M33F Operating Instructions Manual page 241

Hilzinger preheating unit, side view
1 Flange (supply and return)
2 Junction box
Function
The preheating unit is intended to warm up the engine coolant. The circulation pump (6) ensures the
circulation of the preheated coolant through the engine.
The continuous flow heater (4) comprises a heating element. A non-return flap (3) prevents coolant
from flowing through the preheating unit when the engine is running.
When the coolant temperature has reached the value of the thermostat setting (5), the thermostat (5)
switches off the preheating unit via contactors.
In the event of excessive coolant temperature, the temperature limiter of the thermostat (5) opens the
control loop. The preheater is switched off.
The unit must be reset manually after the fault has been rectified.
3 Non-return flap
4 Continuous flow heater
MS150069/02E 2014-03 | Task Description | 241
5 Thermostat
6 Circulation pump