Двигатели Scania четвёртой серии. Руководство — часть 236

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15

H - Descriptions, high pressure

check

H1 - Checking the accumulator

pressure.

1 Start the engine.
2 Start the test Checking the safety valve for

leaks in SDP3.

3 Switch off the engine. Read the pressure

remaining in the accumulator using SDP3.

There should be some pressure remaining.

There are internal leaks if the pressure

approaches 0 bar within 1 min.

H2 - Checking the return fuel pressure

1 Connect pressure gauge 99 362 to the test

connection on the return fuel manifold and

open the test connection.

2 Start the engine. Read the pressure with the

engine idling. The value should be below

0.8 bar. If the pressure exceeds 0.8 bar the

overflow valve on the return fuel manifold

should be cleaned and visually inspected.

Start again from step 1.

Note: Air will come back in when the overflow

valve is removed. It will take some time for the

system to bleed itself. During this time the

measurement is not reliable. Leave the engine

idling for a while before repeating the test. If

the pressure still exceeds 0.8 bar, there is

internal leakage in an injector.

3 Switch off the engine, remove the pressure

gauge and close the test connection.

H - Descriptions

16

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H3 - Checking the safety valve for leaks

!

WARNING!

The accumulator may be under high

pressure. Reduce the pressure using

SDP3 before starting work.
Wear protective goggles.
There is a risk of burn injuries when

safety valve is open.

1 Remove the return pipe 2 from the safety

valve 1 to the return fuel manifold 5.

2 Plug the connection in the return fuel

manifold with cap nut 812 890 or 814 555

and sealing plug 813 878.

3 Refit the return pipe at a slight angle to the

engine. Connect a transparent hose 4 to a

union 3 - 366 082 on the pipe. Pull the hose

down into a can or similar.

4 Start the engine.
5 Start Checking the safety valve for leaks in

SDP3. Follow the instructions in the check.

6 Refit the engine pipes. Torque tighten.

If the check failed:

Check that the following starting conditions

have been met and try again.

•

The engine should be running.

•

Parking brake activated.

•

Gearbox in neutral.

•

Clutch pedal released.

H - Descriptions

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17

H4 - Checking injectors using SDP3

1 Check cylinder balancing at idling speed

using SDP3. Note if any cylinder deviates.

2 Perform a cylinder output test using SDP3.

Note which cylinder deviates from the

others by having a higher output.

3 By comparing the two results with each

other, a cylinder with deviations in both

tests can be identified. Continue

troubleshooting on the injector for that

cylinder.

H5 - Verification of a faulty injector

1 Remove the high pressure pipe to the

injector which has been identified in H4.

2 Plug the outlet of the identified injector at

the outlet port on the fuel accumulator

using tool 99 019. If the outlet port of

cylinder 1 has to be plugged, see the

instructions in TI 03-08 01 28.

3 Start the engine and run it at idling speed

for at least 15 seconds.

4 Switch off the engine. Read the pressure

remaining in the accumulator using SDP3.

If the pressure is more than 0 bar after 1

minute, the faulty injector has been found

and must be renewed. If the faulty injector

cannot be verified, continue

troubleshooting in accordance with H6.

H6 - Checking for internal leaks

!

WARNING!

Wear protective goggles. There is a risk

of fuel splashing from the high

pressure connections when

pressurised.
The accumulator may be under high

pressure. Reduce the pressure using

SDP3 before starting work.

A tool must be made to determine whether the

fuel system is leaking. A pressure regulator, a

switch control valve, two hose couplings, hose

clamps, hose and Tema quick release coupling

1100N for connection to the test connection are

needed. Assemble the parts as illustrated on the

next page. It is vital that all couplings and

connections are tight.

1 Detach and remove all high pressure pipes

between the accumulator and the high

pressure connections.

2 Connect the tool to the test connection on

the return fuel manifold and open the test

connection.

IMPORTANT! Open the fuel filler cap so that

the pressure does not deform the tank.

H - Descriptions

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3 Pressurise the return fuel manifold. Slowly

increase the pressure. Listen for a bubbling

noise in the tank. The bubbling noise

indicates at what pressure the overflow

valve opens. The pressure should be higher

than 0.5 bar. Then pressurise the manifold

to max. 3 bar.

4 Listen for return leakage in the injectors by

blocking one high pressure connection at a

time and quickly removing the obstacle. If

there is internal leakage in the injector, a

hissing sound will be heard.

5 Renew the injector or injectors with

internal leakage as described above.

6 When renewing an injector, the tuning

code of the new injector must be

programmed to the correct cylinder using

SDP3 and basic setting of injector

adaptation must be performed.

IMPORTANT! After renewing an injector with

internal leakage, the engine oil must be

changed and the oil filter renewed. If there is

internal leakage, soot quickly builds up in the

engine oil.

Tool for test pressurising the fuel system

A - Switch control valve

B - Pressure regulator

C - Hose for connection to the fuel system

H - Descriptions