Crank mechanism of the 1.8 liter engine (Sierra)

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Crank mechanism



1 – crankshaft; 2 – intermediate shaft; 3 – crankshaft main bearing shells; 4 – crankshaft thrust…

1 – crankshaft; 2 – intermediate shaft; 3 – crankshaft main bearing shells; 4 – crankshaft thrust half rings; 5 – pulley; 6 – main bearing caps; 7 – connecting rod; 8 – connecting rod cover; 9 – connecting rod bearing shells; 10 – piston; 11 – piston rings; 12 – retaining spring ring; 13 – piston pin; 14 – connecting rod head bushing


Crankshaft



The crankshaft is made of cast iron together with eight counterweights and rests on five main bearings.

Main journal diameter:
- nominal
53.970 – 53.990 mm
- repair -0.25
53,720 – 53,740 mm
- repair -0.50
53.470 – 53.490 mm
Connecting rod journal diameter:
- nominal
48,970 – 48,990 mm
- repair -0.25
48,720 – 48,740 mm
- repair -0.50
48.470 – 48.490 mm
Width of the middle main bearing:
- nominal
31,070 – 31,130 mm
- repair
32,070 – 32,130 mm
Radial clearance of crankshaft main bearings
0.015 – 0.062 mm
Crankshaft axial clearance
0.093 – 0.306 mm
Maximum friction moment in crankshaft main bearings (without piston-connecting rod units installed)
10 Nm



Main bearing shells



The liners are thin-walled. The manufacturer does not provide the dimensions of the liners.

Nominal and repair liners are supplied as spare parts: reduced by 0.25 mm and 0.50 mm.

Connecting rods



Connecting rods are manufactured with four distances between the axes of the head and base holes to ensure the same compression ratio in all engine cylinders. The designations "A", "B", "C" and "D" applied to the side surface of the connecting rod caps determine the selective group of the distance between the axes of the head and base holes.

The method of installing the connecting rod relative to the cylinder block: the letter "F" applied to the side surface of the connecting rod must be on the side of the valve timing drive.

Connecting rod bearing seat bore diameter: 52.000–52.020 mm.

Diameter of the hole in the connecting rod head bushing: 26.012–26.020 mm.

Distance between the axes of the holes in the head and base of the connecting rod:
  • group A: 129.880–129.940 mm;
  • group B: 129.941–130.000 mm;
  • group C: 130.011–130.060 mm;
  • group D: 130.061–130.120 mm.

Connecting rod bearing shells



Thin-walled liners. The manufacturer does not provide the dimensions of the liners. Nominal and repair liners are supplied as spare parts: reduced by 0.25 mm and 0.50 mm.

Pistons



Light alloy pistons with cast steel insert are used.

Piston diameters (measured at right angles to the piston pin axis):
– nominal:
group A
82.460 – 82.475 mm
group B
82.475 – 82.490 mm
group C
82.620 – 82.635 mm
group D
82.635 – 82.650 mm
– repair:
group E (0.5 mm)
82.961 – 82.979 mm
group F (1.0 mm)
83.461 – 83.479 mm
Piston clearance in cylinder:
- groups A and D
0.025 – 0.055 mm
- groups E and F
0.021 – 0.054 mm
The protrusion of the piston bottom above the upper plane of the cylinder block at TDC
0.50 – 0.84 mm



Piston pins



The pin rotates in the piston and connecting rod head bushing (the so-called floating pin) and is fixed from longitudinal movement by two spring retaining rings.

Installing the retaining rings in the piston groove: with the cut facing upwards.

Pin Outer Diameter: 25.996mm–26.000mm.

Piston rings



Each piston has three rings: two sealing rings and one oil scraper ring.

Installation method: the inscription "Top" (top) is directed towards the bottom of the piston.

Width of the lock (cut) of the ring located in the cylinder:
  • top ring (seal): 0.35–0.50 mm;
  • middle ring (sealing): 0.35–0.50 mm;
  • lower ring (oil scraper): 0.25–0.45 mm.

Piston Groove Clearance:
  • top ring (seal): 0.090–0.122 mm;
  • middle ring (seal): 0.050–0.082 mm;
  • lower ring (oil scraper): 0.030–0.065 mm.

Flywheel



Radial runout: 0.13 mm.

Number of teeth on the crown: 135.






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