Overview - Pistons And Connecting Rod

Fig 1: Pistons And Connecting Rod Exploded View

Courtesy of AUDI OF AMERICA, LLC

1. Bolts
   • Tightening Specifications:
     • M8 Bolt: 30 Nm + 90°
     • M9 Bolt: Engine 45 Nm + 90°
   • Always replace after removing.
   • Lubricate the threads and contact surface.
   • Use the old bolts for radial clearance measurement
2. Connecting Rod Bearing Cap
   • Note the installation position
   • Due to the separation procedure (cracking) of the connecting rod, the connecting rod bearing cap only fits in one position and only to the corresponding connecting rod.
   • Use a color to mark the cylinder and connecting rod to which it belongs -A-
   • Installation position: the marks -B- face the belt pulley side
   • Separating the new connecting rod. Refer to NEW CONNECTING ROD, SEPARATING .
3. Bearing Shells
   • Replace any worn bearing shells
   • Installation position. Refer to Fig 4.
   • Coat with engine oil before installing
   • Axial clearance
     • New: 0.10 to 0.35 mm
     • Wear limit: 0.40 mm.
   • Radial play, measuring. Refer to CONNECTING RODS, CHECKING RADIAL CLEARANCE .
4. Connecting Rod
   • Always replace as a set
   • Identify the cylinder and connecting rod bearing cap to which it belongs
   • Installation position: the marks -B- face the belt pulley side
   • Separating the new connecting rod. Refer to NEW CONNECTING ROD, SEPARATING .
   • Radial play, measuring. Refer to CONNECTING RODS, CHECKING RADIAL CLEARANCE .
5. Relief Valve
   • 27 Nm
6. Oil Spray Jet
   • For piston cooling
   • Removing and installing. Refer to OIL SPRAY JETS, REMOVING AND INSTALLING .
7. Circlip
   • Always replace after removing.
8. Piston Pin
   • Coat with engine oil before installing
9. Piston
   • Always replace as a set
   • Mark which cylinder belongs to which
   • Install with the Piston Ring Pliers:T40347 
   • Removing and installing. Refer to PISTONS, REMOVING AND INSTALLING .
   • Installation position: the arrow on piston face points toward belt pulley side.
   • Check piston and cylinder bore. Refer to PISTON AND CYLINDER BORE, CHECKING .
10. Compression Rings
    • Install with Piston Ring Pliers:VAS211003  . Refer to  3.
    • Offset gaps by 120°
    • Installation position in connection with two-piece oil scraping ring: installation position "TOP" "R" must point to the piston crown
    • Allocation and installation position in connection with three part oil scraping ring. Refer to Fig 2.
    • Checking the piston ring gap. Refer to Figure.
    • Checking the groove clearance. Refer to Figure.
11. Oil Scraping Ring
    • Depending on the version two or three part. Refer to the Parts Information for the allocation.
    • Two-Piece Oil Scraping Ring: 
      • Install offset gaps by 120° to the neighboring compression ring
      • The "TOP" or "R" marking must face toward the piston crown.
      • Checking the piston ring gap. Refer to Figure.
      • Height clearance cannot be measured
    • Three Part Oil Scraping Ring: 
      • Remove and install carefully by hand
      • Installation position. Refer to Fig 3.
      • Allocation. Refer to Fig 2.
      • Piston ring gap is not measurable
      • Height clearance cannot be measured

Fig 2: Piston Ring in Connection with the Three-Part Oil Scraping Ring

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1. Compression ring with bevel -arrow A- on the upper side inside. >>TOP<< marking or lettering points upward
2. Compression ring offset -arrow B- on the bottom outside. >>TOP<< marking or lettering points upward
3. Three Part Oil Scraping Ring

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• >>TOP<< marking or lettering points upward.
• Only open the compression ring -2- using the :VAS211003  only until it can be pushed over the pistons -1-.

Fig 3: Three-Part Oil Scraping Ring

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-- Pay attention to the spring installation position:

• The plunger of the plates -2 and 3- and the spring -1- must be offset 90° to each other.

-- Install by hand.

Installation sequence: 

-- Insert the spring -1- in the groove.

-- Insert the lower plate -3- in the groove.

-- Insert the upper plate -2- in the groove.

• Install the upper joint of the 3-part oil scraping ring 120° offset to the neighboring compression ring

Fig 4: Installed Position of Bearing Shell

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-- Place the bearing shells centrally into connecting rod and connecting rod bearing cap.

• Dimension -a- = dimension -a-.