2.14. Piston

Check

Piston

 PERFORMANCE ORDER

  1. Check the external surface of the piston for absence of damage, developments or uneven wear. If necessary, replace the piston.
  2. Check a piston finger, implanting it into a piston opening. The piston finger has to enter smoothly the piston when pressing it a hand (at the room temperature).

Piston rings


 PERFORMANCE ORDER

  1. Check each piston ring for absence of damage and uneven wear. If necessary, replace piston rings.
  2. When replacing the piston it is also necessary to replace piston rings.
  1. Insert a new piston ring into a flute of the piston and measure by the probe a gap between a piston ring and a wall of a flute. If the gap exceeds maximum permissible value, replace the piston.

Gap between a piston ring and a flute in the piston:

Second compression ring: 0,065–0,11 mm
Oil scraper ring: 0.03–0.07

  1. Measure a gap in the lock of piston rings, having manually inserted a piston ring into the engine cylinder. The bottom of the piston push a piston ring in the lower part of the cylinder.
  1. Measure by the probe a gap in the lock of a piston ring.

Gap in locks of piston rings:

First compression ring: 0,2–0,3 mm
Second compression ring: 0,30–0,45 mm
Oil scraper ring: 0,20–0,45 mm

Maximum permissible gap: 0,8 mm

Inserts of conrod bearings

 PERFORMANCE ORDER

  1. Check working surfaces of inserts of conrod bearings for lack of strips, scratches, local corrosion, development and other damages. If necessary, replace inserts. If working surfaces of inserts of conrod bearings are strongly damaged, check a condition of conrod necks of a bent shaft. If the bent shaft is also damaged, replace it or for reuse to a neck pereshlifuyta to the next reduced size.
  1. Measure the internal diameter of inserts of conrod bearings and diameter of necks of a bent shaft. If the oil gap exceeds admissible limits, replace inserts and, if necessary, a bent shaft.

Oil gap in conrod bearings: 0,024 – 0,042 mm
Maximum permissible gap: 0,10 mm

Installation

Rod, piston finger and piston

 PERFORMANCE ORDER

  1. Connect the piston to a rod.
  1. Combine forward tags and implant a piston finger. The piston finger has to enter smoothly the piston when pressing it a hand (at the room temperature). In the presence of a big gap replace a piston finger.

Piston rings

 PERFORMANCE ORDER

  1. Install a dilator of an oil scraper ring and an oil scraper ring on the piston. Establish to Passatizhami for a release of piston rings a compression ring No. 2, then establish a compression ring No. 1. Make sure that tags on piston rings are directed to the piston bottom.
  1. Arrange locks of piston rings, as shown in the drawing.
  1. Install the piston with piston rings over the first cylinder, at the same time the tag on the piston has to be directed to a forward part of the block of cylinders.
  1. Special adaptation squeeze piston rings on the piston. The handle of the hammer press the piston into the cylinder so that the lower head of a rod was established on a neck of a bent shaft.
  1. Establish a connecting rod in a rod cover. Establish a cover of a rod and fix by nuts. Inhaling moment: 25 N • to tighten m on a corner 90 °.

Do not use more than three times bolts of fastening of covers of rods.

  1. Measure by the probe inserted between a rod and a bent shaft a side gap of a rod.

Nominal side gap of a rod: 0,10–0,35 mm
Maximum permissible gap: 0,40 mm