2.2.3. Compression measurement in engine cylinders

NOTE Compression measurement in cylinders of the engine is recommended to be made in the following cases: decrease in the engine capacity, the raised consumption of the engine oil, the increased fuel consumption.

Warm up the engine to normal working temperature, stop it and wait for 10 minutes.

Remove coils of spark plugs

Turn out all spark plugs from heads of the block of cylinders.

Fig. 2.73. Installation компрессометрах

Insert a tip компрессометра into a candle opening of a head of the block of cylinders and measure a compression in engine cylinders (fig. 2.73).

Completely open a butterfly valve.

Consider indications компрессометра at a prokruchivaniye of a cranked shaft of the engine as a starter.

NOTE At compression measurement the storage battery should be completely charged, as for correct measurement it is necessary, that frequency of rotation of a cranked shaft of the engine made not less than 300 mines-1.

Repeat measurement operation for each cylinder.

NOTE Duration of measurement of a compression in each cylinder should be as little as possible.

Compression size for L8 model engines:

- the standard – 1750 kPas (17,855 ^kg/cm2);

- the minimum admissible – 1225 kPas (12,492 ^kg/cm2).

The difference of the measured values of a compression on engine cylinders (for the serviceable engine) should make no more than 196,1 kPas (1,99 ^kg/cm2).

Compression size for LF model engines:

- the standard – 1720 kPas (17,539 ^kg/cm2);

- the minimum admissible – 1204 kPas ^{(12,277¬ú/cm2)}.

The difference of the measured values of a compression on engine cylinders (for the serviceable engine) should make no more than 196,1 kPas (1,99 ^kg/cm2).

Compression size for L3 model engines:

- the standard – 1430 kPas (14,581 ^kg/cm2);

- the minimum admissible – 1000 kPas ^{(10,197¬ú/cm2)}.

The difference of the measured values of a compression on engine cylinders (for the serviceable engine) should make no more than 196,1 kPas (1,99 ^kg/cm2).

If in one or several cylinders the size of a compression is lower minimum admissible, fill in in the cylinder through a candle opening a small amount of engine oil and repeatedly measure a compression in these the cylinder.

If after in the cylinder oil was filled in, the size of a compression increased, wear or damage of piston rings or cylinder walls, most likely, takes place.

If after in the cylinder oil was filled in, the size of a compression did not change, lag of the valve or its leaky landing in a saddle, or leak through laying of a head of the block of cylinders, most likely, takes place.

Establish to the place of a spark plug.

Establish to the place of the coil of spark plugs.