Inspect cooling system for leaks

AR20.00-P-1010RFW

Inspect cooling system for leaks

22.11.2018

Engine

780 in model 253.992/993

1

High temperature cooling circuit cap

5

Expansion reservoir

2

Expansion reservoir

6a

High temperature cooling circuit tester cap

3

Low-temperature circuit cap

6b

Low temperature/high voltage cooling circuit tester cap

4

High voltage cooling circuit cap

7

Pressure pump

 Danger

Risk of explosion caused by escaping hydrogen or overheating of the fuel tanks when working on the hydrogen system. Risk of frostbite to body parts caused by escaping gas and by touching component parts carrying gas when emptying fuel tanks. Risk of asphyxiation caused by inhalation of air diluted by hydrogen. Risk of burn injuries by coming into contact with an invisible pale blue hydrogen flame.

AS00.00-Z-0030-01B

 Warning

Risk of injury to skin and eyes suffering scalding from contact with hot coolantspray. Risk of poisoning from swallowing coolant.

Do not open cooling system unless coolant temperature is below 90 °C. Open cap slowly and release the pressure. Do not pour coolant into beverage containers.
Wear protective gloves, protective clothing and safety glasses.

AS20.00-Z-0001-01A

Topical note

Notes on fuel cell system

AH00.00-P-0022-01RFW

Topical note

Notes on coolant level

AH20.00-P-1142-01RFW

Topical note

Notes on fuel cell coolant

AH06.50-P-0001-01RFW

Topical note

Notes on coolant

AH20.00-N-2080-01A



Remove

1

Ensure that the requirements for driving into the workshop are fulfilled.

Topical note

Requirements for driving into the workshop

AH00.00-P-0021-01RFW

2

Print out "tank system, fuel cell, form event log," fill out, and attach to the vehicle somewhere clearly visible.



OF00.00-P-3000-21RFW

3

Set heating to maximum heating output.

4

Remove engine compartment lining from center and front.

AR61.20-P-1105LW

5

Remove underfloor paneling in the area of the coolant hoses and lines.

AR61.30-P-1001RFW

Check (high temperature cooling circuit)

6

Unscrew high temperature cooling circuit cap (1) slowly from the expansion reservoir (2) and carefully relieve overpressure.

 The cooling system of the fuel cell vehicle consists of three independent cooling circuits.
The high temperature cooling circuit of the fuel cell major assembly uses a different coolant than the low-temperature circuit and the high voltage cooling circuit.

 Do not mix the different kinds of coolant.

 The high temperature cooling circuit cap (1) for the fuel cell system has a yellow coloration.

7

Screw on high temperature cooling circuit tester cap (6a).

 Adapter

*253589039100

8

Connect pressure pump (7) to the high temperature cooling circuit tester cap (6a).

 Adapter

*253589039100

 Pressure pump

*124589242100

9

Apply test pressure to the high temperature cooling circuit for 2 minutes.


Do not exceed the specified test pressure.
Otherwise, damage to the high temperature cooling circuit will occur.

 There should be no pressure loss within a period of 2 minutes.

Test pressure for pressure-testing the engine cooling system

*BE20.30-P-1005-03A

If pressure loss occurs,



Perform visual inspection of components carrying coolant.

10

Relive overpressure via the valve on the pressure pump (7).

 Pressure pump

*124589242100

11

Remove pressure pump (7) from the high temperature cooling circuit tester cap (6a).

 Adapter

*253589039100

 Pressure pump

*124589242100

12

Unscrew high temperature cooling circuit tester cap (6a).

 Adapter

*253589039100

13

Check coolant level of the coolant; correct if necessary.

Check (low-temperature circuit)

14

Unscrew low-temperature circuit cap (3) slowly from the expansion reservoir (2) and carefully relieve overpressure.

 The low-temperature circuit cap (3) has a black coloration.

15

Screw on low temperature/high voltage cooling circuit tester cap (6b).

 Test cap

*210589009100

16

Connect pressure pump (7) to the low temperature/high voltage cooling circuit (6b) tester cap.

 Pressure pump

*124589242100

 Test cap

*210589009100

17

Apply test pressure to the low-temperature circuit for 2 minutes.


Do not exceed the specified test pressure.
Otherwise, damage occurs to low-temperature circuit.

 There should be no pressure loss within a period of 2 minutes.

Test pressure for pressure-testing the engine cooling system

*BE20.30-P-1005-03A

If pressure loss occurs,



Perform visual inspection of components carrying coolant.

18

Relive overpressure via the valve on the pressure pump (7).

 Pressure pump

*124589242100

19

Remove pressure pump (7) from low temperature/high voltage cooling circuit tester cap (6b).

 Pressure pump

*124589242100

 Test cap

*210589009100

20

Unscrew low temperature/high voltage cooling circuit tester cap (6b).

 Test cap

*210589009100

21

Check coolant level and antifreeze content of the coolant; correct if necessary.

 Coolant mixing ratio

*BF20.00-P-1001-04A

Check (high voltage cooling circuit)

22

Unscrew high voltage­cooling circuit cap (4) slowly from the expansion reservoir (5) and relieve overpressure carefully.

 The high voltage­cooling circuit cap (4) has a black coloration.

23

Screw on low temperature/high voltage cooling circuit tester cap (6b).

 Test cap

*210589009100

24

Connect pressure pump (7) to the low temperature/high voltage cooling circuit (6b) tester cap.

 Pressure pump

*124589242100

 Test cap

*210589009100

25

Apply test pressure to high voltage cooling circuit for 2 minutes.


Do not exceed the specified test pressure.
Otherwise, damage to the high voltage cooling circuit will occur.

 There should be no pressure loss within a period of 2 minutes.

Test pressure for pressure-testing the engine cooling system

*BE20.30-P-1005-03A

If pressure loss occurs,



Perform visual inspection of components carrying coolant.

26

Relive overpressure via the valve on the pressure pump (7).

 Pressure pump

*124589242100

27

Remove pressure pump (7) from low temperature/high voltage cooling circuit tester cap (6b).

 Pressure pump

*124589242100

 Test cap

*210589009100

28

Unscrew low temperature/high voltage cooling circuit tester cap (6b).

 Test cap

*210589009100

29

Check coolant level and antifreeze content of the coolant; correct if necessary.

 Coolant mixing ratio

*BF20.00-P-1001-04A



Install

30

Install underfloor paneling in the area of the coolant hoses and lines.

AR61.30-P-1001RFW

31

Install engine compartment lining at center and front.

AR61.20-P-1105LW

Check values for engine cooling system cap

Number

Designation

Engine 780 in model 253.992/993
with code ME02 (Fuel cell)
Cap for high-temperature cooling system

Engine 780 in model 253.992/993
with code ME02 (Fuel cell)
Cap for high-voltage battery low-temperature circuit

BE20.30-P-1005-03A

Test pressure for pressure-testing the engine cooling system

Overpressure

bar

0,8

1,4

 Coolant mixing ratio

Number

Designation

Engine all (4xWD, CAR, smart)

BF20.00-P-1001-04A

Coolant mixing ratio

Antifreeze/water

Up to -37°C

%

50/50

As of -38 °C

%

55/45

Overview and specifications sheet

BB00.40-P-0310-01A

References to sheet specification

BB00.40-P-0310ZZ