Piston, Engine

WM 1310IN Piston wear, weight groups and identification markings

Information

Weight groups and identification markings

- Original pistons from the Porsche Spare Parts Catalogue are only available in the dimensional group X.

- Observe the different weight groups.

Identification markings:





Piston markings





Weight groups:





Checking

Checking for wear

WARNING

Caustic fluids

- Danger of chemical burns

-> Avoid contact with caustic fluid.
-> Wear personal protective gear.
-> Ensure that there is good ventilation.
-> If you do come into contact, wash off immediately with plenty of warm water and contact a doctor if necessary.

Information

- When cleaning pistons, be careful of the hard layer on the first ring groove.

- Be careful of the twist lock for the second ring groove.

1. Clean removed pistons with solvent naphtha or acetone first. To determine the dimensional group (engraved on the piston crown), carbon deposits must be removed carefully.
1.1. To do this, we recommend that you clean the piston crown in an ultrasound bath or using a brass brush.

Information

- If the wear limit is exceeded, the piston must be replaced.

2. Check the piston diameter -D- at the prescribed measuring point on the piston shank using an outside micrometer.
Measuring point from lower edge of shank dimension X = 15 mm.





Checking the piston shank diameter

The maximum wear allowed at the specified measuring point is 100 micrometer (= 0.1 mm). If this measurement is exceeded, the piston must be replaced. The reference measurements are listed in the table below.

Dimensional groups:





Piston rings and piston ring groove:

Piston rings:
3. Check piston rings for signs of wear.
3.1. Piston-ring end clearance is measured in the cylinder.





Piston rings:





Piston pin:
- Check for signs of wear and tear.
- Dimensional check using outside micrometer: diameter = 22.0 - 0.02 mm.