Fuel Tank: Testing and Inspection

16 00 100 Checking fuel tank and tank ventilation system for leaks (diesel)

Special tools required:







Necessary preliminary tasks:
- Remove rear right wheel arch panel







Comply with the following conditions in order to obtain plausible measuring results:
- Content of fuel tank:
1. Maximum 90 %
2. Minimum 13 % (fuel reserve indicator light must not light up).
- Park the vehicle in the workshop at least 2 hours before the test so that the fuel temperature is approximately that of the workshop temperature (ideal fuel temperature approx. 10 ... 20°C)







Pull off protective cap (1) vertically upwards from fuel filler pipe.

IMPORTANT: The original protective cap must be refitted on completion of work.







Attach special tool 16 1 176 vertically from above to valve on fuel filler pipe (1).

IMPORTANT: Special tool 16 1 176 must perceptibly and audibly engage.







IMPORTANT:
Make sure that special tool 16 1 176 is removed again on completion of the work.
Otherwise, tank ventilation will not be possible and this will result in damage to or failure of the tank system.







Remove fuel filler cap and connect special tool 16 1 174 to fuel filler neck.
Using hand wheel (1), clamp special tool 16 1 174 to fuel filler neck.







IMPORTANT: Turn pressure regulator on special tool16 1 171 anticlockwise as far as the stop.







Using compressed air line (1), connect special tool 16 1 171 to workshop compressed air system (8 ... 10 bar).
Connect pressure sensor (2) from Diagnosis and Information System with a measuring range of 0 ... 25 bar.

IMPORTANT: Do not connect quick-release coupling (3) of special tool 16 1 171as yet.







1. Select "Measurement" function on Diagnosis and Information System (DIS).
2. Using pressure regulator on special tool 16 1 171, increase displayed pressure by 0.20 bar.
3. Connect special tool16 1 174 to quick-release coupling of special tool 16 1 171.
4. Wait until the value at the Diagnosis and Information System has levelled out.
5. Using pressure regulator on special tool 16 1 171, reset pressure in fuel tank to 0.20 bar excess pressure.







IMPORTANT: Do not under any circumstances increase pressure by more than 0.30 bar as this would result in damage to the fuel tank and tank ventilation system.







Using special tool 13 3 010, disconnect feed line from special tool 16 1 171 to fuel filler neck.
Allow a rest period of approx. 20 sec.
Read off and note down starting pressure value.
Wait approx. 120 sec.
Read off final pressure value and compare with starting pressure value.







Measurement evaluation:
- Pressure drop up to 0.01 bar:
System OK
- Pressure drop over 0.02 bar:
System leaking beyond permitted levels

If the system is leaking, a leak detection must be carried out and the defective components replaced.