Audi Q7 2007
!
6-cylinder TDI engine (3.0 ltr. 4-valve common rail), mechanics 01.2006
4 Dismantling and assembling pistons and conrods
97
6
"
Checking
⇒
Fig. on page 98
"
Install using piston ring clamp
"
If cracking is visible on piston skirt, renew piston
"
Piston and cylinder dimensions
⇒
page 100
"
Checking piston projection at “TDC”
⇒
page 99
"
Checking cylinder bore
⇒
Fig. on page 98
8 - Piston rings
"
Offset gaps by 120
°
"
Remove and install using piston ring clamp
"
“TOP” must face towards piston crown
"
Checking ring gap
⇒
Fig.
"
Checking ring-to-groove clearance
⇒
Fig.
Oil spray jet for piston cooling
1 - Bolt, 9 Nm
2 - Oil spray jet with spray nozzle valve for piston cooling
Checking piston ring gap
–
Insert ring at right angle to cylinder wall from above and
push down into lower cylinder opening approx. 15 mm
from bottom of cylinder. To do so, use a piston without
rings.
Checking ring-to-groove clearance
–
Clean groove in piston before checking clearance.
Piston ring
Dimensions in mm
New
Wear limit
1st compression ring
0.25 … 0.38
0.80
2nd compression ring
0.70 … 0.90
1.30
Oil scraper ring
0.40 (maxi-
mum)
0.70
Piston ring
Dimensions in mm
New
Wear limit
1st compression ring
0.120 … 0.160
0.175
2nd compression ring
0.020 … 0.090
0.115
Oil scraper ring
0.020… 0.090
0.115
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