Subaru Legacy

since 1990-1998 release

Repair and operation of the car



Subaru of Legasi
+ 1.1. Identification numbers
+ 2. Maintenance
- 3. Engines
   3.1. Technical characteristics
   3.2. Operations on repair of the engine installed in the car
   3.3. Top dead point of the first cylinder
   3.4. Cover of a head of the block of cylinders
   3.5. Inlet collector
   + 3.6. Gear belt and pulleys
   3.7. Replacement of a forward sealing ring of a cranked shaft
   3.8. Replacement of sealing rings of camshafts
   3.9. Camshafts and pushers
   3.10. Heads of the block of cylinders
   3.11. Oil pallet
   3.12. Oil pump
   3.13. Drive flywheel / plate
   3.14. Replacement of a back sealing ring of a cranked shaft
   3.15. Suspension bracket of the power unit
   - 3.16. Capital repairs of the engine
      3.16.1. Technical characteristics
      3.16.2. Check of a compression
      3.16.3. Check of the engine by means of the vacuum gage
      3.16.4. Recommendations about removal of the engine
      3.16.5. Removal of the engine
      3.16.6. Sequence of dismantling of the engine
      3.16.7. Dismantling of a head of the block of cylinders
      3.16.8. Cleaning and survey of a head of the block of cylinders
      3.16.9. Assembly of a head of the block of cylinders
      3.16.10. Removal of pistons
      3.16.11. Division of sections of blocks of cylinders
      3.16.12. Removal of a cranked shaft with rods
      3.16.13. Block of cylinders of the engine
      3.16.14. Honingovaniye of cylinders
      3.16.15. Rods
      3.16.16. Cranked shaft
      3.16.17. Survey of radical and shatunny bearings
      3.16.18. Balance of assembly of the engine at capital repairs
      3.16.19. Survey of pistons
      3.16.20. Check of working gaps of shatunny bearings
      3.16.21. Check of working gaps of radical bearings of a cranked shaft
      3.16.22. Assembly of sections of the block of cylinders
      3.16.23. Installation of piston rings
      3.16.24. Installation of pistons
      3.16.25. Installation of the engine
      3.16.26. Start of the engine after capital repairs
+ 4. Heating, ventilation
+ 5. Fuel system
+ 6. Exhaust system
+ 7. Systems of start, ignition
+ 8. Transmissions
+ 9. Coupling, shaft
+ 10. Brake system
+ 11. Suspension bracket
+ 12. Steering
+ 13. Body
+ 14. Electric equipment


3a942d17



3.16.2. Check of a compression

GENERAL INFORMATION

In case of reduction of engine capacity which is not defect of ignition or fuel system, check of a compression can define a condition of the engine. If check is carried out regularly, it is possible to define defect which will be shown soon.

The engine has to be heated-up up to the working temperature. Level of oil has to meet standard and the accumulator is completely charged. Also the help of other person will be required.

PERFORMANCE ORDER
1. Unscrew all spark plugs from the engine.
2. Disconnect electric sockets from the coil of ignition and the fuel pump.
3. Screw in a tip of a kompressometr in an opening of a spark plug of the N 1 cylinder.
4. The assistant has to press against the stop a pedal of an accelerator and turn the engine a starter within several seconds. Thus it is necessary to watch indications of a kompressometr.
5. Pressure will grow quickly enough at the serviceable engine. Low pressure on the first piston stroke accompanied with gradual increase in pressure on the following courses indicates worn-out piston rings.
6. Low pressure on the first course which does not increase further, indicates leaky valves or the punched laying of a head of the block of cylinders.
7. Deposits on a reverse side of plates of valves can promote low pressure also. Make record of the most high pressure. Then repeat procedure for the remained cylinders.
8. Because of a variety of kompressometr and speed of rotation of a cranked shaft of the engine data often differ in a starter when checking a compression. For this reason the actual pressure of compression is not specified, however the most important factor is that pressure have to be identical in all cylinders.
9. Add to cylinders insignificant amount of engine oil (about 20 cm3) through an opening for spark plugs and then repeat tests. If there is an increase in pressure after oil is added, indicative that piston rings are worn-out.
10. If pressure does not increase, available leak in valves or laying of a head of the block of cylinders. Leakage of valves can be caused by the burned saddles or plates of valves or the bent valves.
11. If two adjacent cylinders have equally low pressure, it is the most probable that laying of a head of the block of cylinders burned through between them. Emergence of cooling liquid in the combustion chamber or on the probe for measurement of level of engine oil confirms this defect.
12. If pressure in one cylinder is about 20% lower, than in other and the engine has slightly rough mode of idling, the worn-out cam on distributive to a shaft can be the cause of it.
13. After check of a compression establish spark plugs and connect electric sockets to the coil of ignition and the fuel pump.