Disassembling Pistons

→ Wear personal protective gear.

→ Secure components to prevent them from falling off suddenly.

Information 

• Combustion deposits on the piston crown are not to be removed mechanically! 

Fig 1: Overview Of Piston/Connecting Rod

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1. Piston rings (move gap by 120°)
2. Piston
3. Circlip
4. Connecting rod
5. Connecting rod bearings must always be replaced  . Observe relevant classification.
6. Connecting rod bearing cap
7. Connecting rod bolts
8. Cylinder block
9. Piston pin

1. Insert piston in retaining device 9597  .
   Fig 2: Inserting Piston Pin And Connecting Rod In Retaining Device 9597

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   1. 1.1. Adjust the length of the retaining device .
   2. 1.2. Insert piston and connecting rod.
   3. 1.3. Fix the length of the retaining device.

      Information 

      • When disassembling the piston/connecting rod unit, note or mark the position, relationship to cylinder and installation position using a waterproof felt tip pen. 
      • Some Figures show the piston of the V8 as the work steps are analagous. 
2. Disconnect piston from the connecting rod.
   Fig 3: Removing Piston-Pin Circlips

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   1. 2.1. Remove piston-pin circlip using a small screwdriver.
   2. 2.1.1. Guide the screwdriver through the small cut-out.
   3. 2.2. Repeat the process for the second piston-pin circlip.

      Information 

      • If piston is sluggish, heat to 60 °C and remove and install with mandrel. 
   4. 2.3. Then slide out the piston pin using a suitable mandrel.
      Fig 4: Removing Piston Pin Using Mandrel

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   5. 2.4. Pull connecting rod out of the piston and lay it side.
3. Remove piston rings using the piston ring pliers, size 1 Nr.58  .
   NOTE: Incorrect handling of piston rings

   • Risk of strain and damage to piston rings

   → Only open up the piston ring using the piston ring pliers sufficiently to allow you to remove or fit it.

   → Do not use force to install pistons.

   NOTE: Incorrect handling of piston rings

   • Risk of strain and damage to piston rings

   → Only open up the piston ring using the piston ring pliers sufficiently to allow you to remove or fit it.

   → Do not use force to install pistons.

   1. 3.1. Place the piston on a clean surface.
   2. 3.2. Remove the piston rings, starting from the piston crown.
   3. 3.3. To do this, place the middle point of the piston ring pliers at the gap in the piston ring.
   4. 3.4. The holding arms of the piston ring pliers should clasp the piston ring from above.

      Information 

      • Compression rings and oil scraper rings are installed and removed differently. 

        Only open the piston ring as much as is needed to remove the piston ring from the groove.

        Fig 5: Removing Piston Ring From Groove

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   5. 3.5. Relieve the piston ring pliers and remove the piston ring from the pliers.
4. Remove the oil scraper rings (three parts).
   1. 4.1. Remove the top oil scraper ring.
   2. 4.2. Remove the bottom oil scraper ring.
   3. 4.3. Then carefully remove the spring.