Overview - Pistons And Connecting Rod

Fig 1: Pistons And Connecting Rod Exploded View

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1. Bolts
   • 45 Nm + 90°
   • Always replace after removing
   • Coat the threads and contact surfaces with engine oil
   • 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
   • New: 0.10 to 0.35 mm
   • Wear limit: 0.40 mm.
   • Replace any worn bearing shells
   • Coat with engine oil before installing
   • Axial clearance
   • Radial play, measuring. Refer to CONNECTING RODS, CHECKING RADIAL CLEARANCE .
   • Installation position. Refer to Fig 2.
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
   • Installation position. Refer to Fig 6.
   • 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
   • Mark which cylinder belongs to which
   • Install with the Piston Installation Tool:T40347 
   • Installation position: the arrow on piston face points toward belt pulley side.
   • Check piston and cylinder bore. Refer to PISTON AND CYLINDER BORE, CHECKING .
   • Removing and installing. Refer to PISTONS, REMOVING AND INSTALLING .
10. Compression Rings
    • Offset gaps by 120°
    • Install with Piston Ring Pliers :VAS211003  . Refer to Fig 4.
    • Allocation and installation position. Refer to Fig 3.
    • Checking the piston ring gap. Refer to Figure.
    • Checking the groove clearance. Refer to Figure.
11. Oil Scraping Ring
    • Two or three part depending on the version.
    • Carefully remove and install the three-part oil scraping ring by hand
    • Install the upper joint of the 3-part oil scraping ring 120° offset to the neighboring compression ring
    • Piston ring gap is not measurable
    • Side clearance cannot be measured.
    • Installation position. Refer to Fig 5.
    • Allocation. Refer to Fig 3.

Fig 2: 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-.

Fig 3: Allocation of the 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

Fig 4: Installing the Compression Ring

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

Fig 5: 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: 

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

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

-- 3. 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 6: Oil Spray Jets Installation Position

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• The side surface of the oil spray jet -1- must be parallel to the neighboring crankshaft bearing -2-.
• Dimension -a- = dimension -a-.