2.2.3. Measurement of a compression in engine cylinders

NOTE Measurement of a compression in cylinders of the engine is recommended to be performed in the following cases: deceleration of power of the engine, the raised consumption of engine oil, the increased fuel consumption.

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

Remove coils of spark plugs

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

Fig. 2.73. Installation kompressometra

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

Completely open a butterfly valve.

Consider indications of a kompressometr when scrolling a bent shaft of the engine a starter.

NOTE At measurement of a compression the rechargeable battery has to be completely charged as it is necessary for correct measurement that the frequency of rotation of a bent shaft of the engine made not less than 300 min.-1.

Repeat operation of measurement for each cylinder.

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

Compression size for L8 model engines:

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

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

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

Compression size for LF model engines:

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

- minimum admissible – 1204 kPa ^{(12,277kg/cm2)}.

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

Compression size for L3 model engines:

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

- minimum admissible – 1000 kPa ^{(10,197kg/cm2)}.

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

If in one or several cylinders the size of a compression is lower than 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, then, most likely, wear or damage of piston rings or walls of the cylinder takes place.

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

Establish to the place of a spark plug.

Establish to the place of the coil of spark plugs.