Audi A8 2003 Workshop Manual page 105

8-cylinder TDI engine (4.2 ltr. 4-valve common rail), mechanics - Edition 12.2013
5 - Circlip
6 - Piston pin
❑ If difficult to move, heat piston to approx. 60 °C
❑ Remove and install using drift - VW 222 A-
7 - Piston
❑ Removing and installing
❑ Piston installation position and piston/cylinder allocation
❑ Use chalk or waterproof felt-tip pen to mark cylinder allocation on piston crown.
❑ Renew piston if cracking is visible on piston crown or piston skirt
❑ Install using piston ring clamp
❑ Checking ⇒ page 100
❑ Measuring cylinder bore
❑ Measuring piston projection at TDC
❑ Piston and cylinder dimensions, piston allocation for cylinder bore
8 - Piston rings
❑ Offset gaps by 120°
❑ Use piston ring pliers to remove and install
❑ Marking "TOP" or side with identification mark must face piston crown
❑ Measuring ring gap
❑ Measuring ring-to-groove clearance
Oil spray jet for piston cooling
1 - Bolt, 9 Nm; renew (self-locking)
2 - Oil spray jet with spray nozzle valve for piston cooling
Note
Do not bend oil spray jets.
♦
Renew oil spray jets if bent.
♦
Measuring piston ring gap
– Insert piston ring at right angle to cylinder wall from above and
push down into lower cylinder opening approx. 15 mm from
bottom of cylinder.
– Use a piston without piston rings to push in the ring.
Piston ring
Dimensions in mm
1st compression ring
2nd compression ring
Oil scraper ring
⇒ page 101
⇒ page 100
⇒ page 103
⇒ page 99
⇒ page 100
New Wear limit
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5. Dismantling and assembling pistons and conrods
Audi A8 2003 ➤
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