Conrod and piston group. Nissan Almera (from 1995 to 1999 release)
Service of Nissan Almera from 1995 to 2000 in N15 body
1. General information
2. General requirements to car repairs
3. Operation and maintenance of the car
4. Petrol engines
4.1. Removal and installation of the power unit
4.2. Dismantling and assembly of the engine
4.3. Block of cylinders
4.4. Conrod and piston group
4.4.1. Check of technical condition
4.5. Bent shaft and flywheel
4.6. Gas distribution mechanism
4.7. Head of the block of cylinders of GA14DE and GA16DE engines
4.8. Head of the block of cylinders of the SR20DE engine
4.9. Cooling system
4.10. Lubrication system
4.11. System of production of the fulfilled gases
4.12. Power supply system
4.13. Complex Control System of the Engine (CCSE)
5. Diesel engines
6. Transmission
7. Running gear
8. Steering
9. Brake system
10. Electric equipment
11. Body
12. Appendices
13. Schemes of electric equipment
 









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4.4. Conrod and piston group

Pistons are manufactured of aluminum alloy, have the flat bottom and three flutes for rings.
On diameter pistons are broken into three groups for the nominal size and into two groups for the repair size (tab. 2.2).

Table 2.2  Dimensional groups of pistons
Diameter of the piston, mm
Engine model
GA14DE
GA16DE
SR20DE
1 - group of the nominal size
73,575-73,585
75,975-75,985
86,00-86,01
2nd group of the nominal size
73,585-73,595
75,985-75,995
86,01-86,02
3rd group of the nominal size
73,595-73,605
75,995-76,005
86,02-86,03
Repair group  - t-0,5
74,075-74,105
76,475-76,505
-
Repair   group +0,1
74,575-74,605
76,975-77,005
-
Repair   group +0,2
-
-
86,18-86,21


Dimensional groups are marked by figures on the piston bottom. Pistons of the repair sizes intend for installation in the block of cylinders after boring. The tag on the bottom of the piston has to be turned towards the drive of camshafts.
Diameter of an opening in lugs under a piston finger makes, mm:
for       GA 18,987—18,999 engines
for       SR 21,987—21,999 engines
The gap between a mirror of the cylinder and the piston makes, mm:
for       GA 0,015—0,035 engines
for       SR 0,01—0,03 engines
Piston fingers hollow, steel, tempered and polished, freely rotate in the plug of a rod and are pressed by small effort in a cold state in an opening of lugs of the piston. Fingers refrain from axial movement by two spring lock rings.
Diameter of a piston finger, mm:
       GF 18,989—19,001 engines
for       SR 21,989—22,001 engines
Tightness in an opening of a lug of the piston of 0 — 0,004 mm. A gap between a piston finger and the plug of the top head of a rod of 0,005 — 0,017 mm.

Fig. 2.4. Installation of piston rings: I \order of installation of piston rings; II \arrangement of locks of piston rings; 1 — the tag on the piston directed towards the drive of camshafts; 2 — a joint of a dilator of an oil scraper ring; 3 — the lock of the top compression and top oil scraper ring; 4 — the lock of an oil scraper ring; 5 — the lock of the lower compression ring


On each piston about three rings (fig. 2.4) are established: top compression chromeplated, with a barrel-shaped surface; lower compression scraper type; oil scraper with a dilator, top and lower rings.
The gap between piston rings and flutes of the piston makes:
— for the top ring — 0,04 — 0,08 mm, maximum permissible 0,2 mm;
— for the lower ring — 0,03 — 0,07 mm, maximum permissible 0,2 mm.
Gap in the lock:
— for the top ring — 0,2 — 0,35 mm;
maximum permissible for GA engines — 1 mm;
maximum permissible for SR engines — 0,49 mm;
— for the lower ring — 0,37 — 0,52 mm;
maximum permissible for GA engines — 1 mm;
maximum permissible for SR engines — 0,64 mm;
— for an oil scraper ring — 0,2 — 0,6 mm;
maximum permissible for GA engines — 1 mm;
maximum permissible for SR engines — 1,09 mm.
Rods steel, shod, double-T section, the lower head of a rod with the direct socket. At installation the tag on a cover of the lower head of a rod settles down opposite to a tag on a rod; the opening for lubricant is guided towards a starter.
The distance between centers of openings of the top and lower heads of a rod of GA engines makes 140,45 — 140,55 mm.
Diameter of an opening of the lower head of a rod, mm:
       GA 43,000—43,012 engines
       SR 51,000—51,013 engines
Diameter of an opening of the plug of the top head of a rod, mm:
       GA 19,000—19,012 engines
       SR 22,000—22,012 engines


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