Двигатели Scania четвёртой серии. Руководство - часть 236

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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

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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