0010 - Function of the injection system E. Fuel pre-heating (148) (note deviations for off-road vehicles) Engines 601, 602.91, 603.91

07.1-010 Function injection system

E. Fuel preheating (148)

A heat exchanger (148) for preheating the fuel is installed in the supply line of the heating system.

Heat exchanger

C Supply

D Return

E Heater supply

148 Heat exchanger

Note

As a result of material conversion the fuel thermostat of engines 601.911/912 is made of plastic, previously die cast aluminium.

Production breakpoint: December 1990 - February 1991

Standard production breakpoint: as of July 1991

Function

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Model 124, 201

Full preheating up to +8 °C fuel temperature; the required fuel is drawn via the heat exchanger by the fuel pump.

From +8 °C to +25 °C mixed operation; the required fuel flows partially via the heat exchanger.

Above +25 °C the heat exchanger is
by-passed by the thermostat action; the fuel pump draws the fuel directly.

Fuel thermostat

A Supply from fuel tank

B Suction line to fuel pump

C Supply to heat exchanger

D Return from heat exchanger

Model 202

The thermostat is positioned on the outside at the heat exchanger.
The thermostat cuts in and cuts off at the following fuel temperatures:

Full preheating up to +18 °C,

mixed mode from +18 °C to +30 °C,

no preheating as of +30 °C.

A Feed from fuel tank

B Suction line to fuel pump

E Coolant inlet

F Coolant outlet

As a result of the fuel preheating trouble-free operation with winter diesel fuel is generally possible down to approx. - 25 °C outside temperature.

Function diagram fuel preheating

54	Injection line cylinder 1
63	Fuel tank
73	Fuel filter upper part
73a	Choke orifice in fuel filter upper part
86	Fuel thermostat up to +8 °C
86a	Fuel thermostat above +25 °C
87	Supply line (cold fuel)
87a	Return line (preheated fuel)
148	Fuel heat exchanger

1	Injection pump
3	Fuel pump
15	Overflow valve with choke 1.5 mm dia.
30	Nozzle holder combination
42	Fuel filter
42a	Choke orifice in fuel filter upper part 0.8 mm diameter
43	Fuel prefilter
50	Leak-off fuel hose