Replace spark plugs

AP15.10-W-1580A

Replace spark plugs

19.11.2019

Engine

902.9, 906.9 in model 957

with code MS8 (Natural gas engine)

Modification notes

26.02.2013

Remove spark plugs (2), for engine 902.9 as of engine end no. 970515, added.

Operation step 7

AR01.30-W-5461C

1

Spark plug connector

2

Spark plug

 

Remove/install

 Danger

Risk of explosion due to escaping combustible gas or overheating of gas cylinders.Risk of injury caused by burns to skin and eyes. Risk of frostbite to body parts caused by escaping gas and by touching components near the valves when emptying gas cylinders. Risk of poisoning or suffocation caused by inhaling gas.

Remove any sources of ignition.
Protective clothing, safety gloves and safety glasses must always be worn.
Ensure that the work area is adequately ventilated.
When working on vehicles at ambient temperatures over 60 °C, all gas cylinders must be removed.

AS00.00-Z-0018-01A

 Danger

Risk of death when working on component parts and systems with U >= 30 V alternating voltage (AC) or U >= 60 V direct voltage (DC)

Do not touch damaged or defective live component parts and lines or non-insulated electrical connections and lines.

AS00.00-Z-0035-01A

Notes on work safety regulations for vehicles with natural gas-powered engines

AH00.10-N-1000-04A

1

Switch off ignition

2

Open maintenance flap

 Warning

Risk of injury caused by body parts being pinched or crushed as cab is tilted

Ensure that no one is within the tilting range of the cab as it is being tilted. Always tilt the cab all the way to the end position and secure it with the safety strut.

AS60.80-Z-0001-01A

3

Tilt cab

Topical note

Notes on tilting the cab

AH60.80-N-0003-01A

4

Clean recesses around spark plug holes on cylinder head cover

5

Unclip spark plug connector (1) from brackets

6

Pull spark plug connectors (1) out of the spark plug holes

 Mark assignment of the spark plug connectors (1) relative to the cylinders.

 Installation: Pay attention to marking.

 Pliers

*611589003700

7

Remove spark plugs (2)


When a jammed spark plug (2) is loosened, the protective sleeve in the cylinder head can become detached and, as a result, coolant can enter the cylinder combustion chamber.
This coolant can cause engine damage when the engine is started.

 Spark plug in cylinder head

*BA07.54-N-1003-01A

 Spark plug wrench

*112589010900

If the protective sleeve has become detached:



Install a new protective sleeve subject to a separate repair order:



Engine 902.9 as of engine end no. 970515

AR01.30-W-5461C



Engine 902.9 up to engine end number 970514, 906.9

AR01.30-W-5461H

 Installation: Only approved spark plugs should be installed.

8

Install in the reverse order

 Gas injection and ignition system

Number

Designation

Engine 902.9 with code MS8, engine 906.9 with code MS8

BA07.54-N-1003-01A

Spark plug in cylinder head

Up to engine end number 970514

Nm

25

As of engine end number 970515

Nm

35