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Check compression pressure assessment cylinders

Check the compression pressure

To perform the verification procedures of the compression pressure will need assistance assistant.

Measurement of compression pressure allows an overview of the current state of internal engine components such as cylinder head gasket, valve train components, pistons and piston rings. Analysis of the test results to determine whether the engine is in need of major refurbishment, or simply replace the head gasket. The measurement is made using the compression tester.

For diesel engines Compression needs to limit measurements to about 40 bar.

Petrol models

Diesel models

PERFORMANCE ORDER

Remove the fuel feed pipes, nozzles, flat and corrugated washers (cm. Power supply systems, engine control / emission control and exhaust). Disconnect the electrical wiring from the fuel shut-off valve (see. Power supply systems, engine control / emission control and exhaust). If the valve is switched off, the fuel pump will start spraying when turning the engine! A suitable plug plug the fuel return pump. With the transition nozzle special plug gauge to the nozzle hole of the first cylinder. Ask the assistant is not squeezing the pedal several times to crank the engine starter. Consider the maximum meter reading, the result of record. To obtain reliable results the engine should be rotated at least eight turns. Operating in a similar manner, measure the compression pressure in the remaining cylinders. Disconnect the compression gauge and refit the components acting in film. Restore initial connection of fuel lines and electrical wiring - be sure to remove the cap from the injection pump return line.

All models

Compare the results of the measurement requirements of Specifications of the Head of Engine.

Maximum permissible differential pressure in the individual cylinders can be 1.5 kgf / ^cm 2 for petrol engines and 3.0 kgf / ^cm 2 for diesel.

Compression in the serviceable engine is growing very fast. Low value shown after the first cycle, increases with subsequent cycles indicates the wear of piston rings. If the pressure does not increase with repetition of cycles, check the tightness of the closing valves and the integrity of the cylinder head (not excluded as the likelihood of cracks in the head).

Carbon formation on the plates of valves can also lead to a reduction of the compression pressure.

It will be appreciated that due to the different speed of starter results in different vehicles may vary slightly, but the statements for all the cylinders of the engine should be approximately equal.

If the pressure in any cylinder is at or below the minimum allowable, try to pour into the cylinder through the spark plug hole teaspoon of motor oil and recheck. If the addition of oil leads to a temporary recovery compression reason its reduction, likely it is the wear of the piston, piston rings or the cylinder wall. If you increase the compression has occurred, it can be concluded tightness closing valves or damaged gasket / cylinder head casting.

Equally low compression in two next cylinders with a high degree of probability points to a violation of the integrity of the head gasket in the area of bridge between the cylinders. The presence of coolant in the combustion chamber / crankcase may serve as confirmation of this assumption.

If compression in one of the cylinders by approximately 20% lower than in the other, and at the same time has been a violation of stability idling speed should assess the degree of wear of the working protrusions relevant cams of a camshaft.

Leak test cylinder

PERFORMANCE ORDER

During this test the tightness of the cylinder is estimated (by the speed of release of the injected pressurized air in them), and - in case of violation, - localized sources of leaks. This test is an alternative to checking compression pressure, as from a certain point of view, the latter is much more effective as visually identify the source of the leak easier than doing speculative conclusions based on indirect evidence. Warm up the engine to normal operating temperature (80 ?� C), then stop it. Remove the expansion tank cap of the cooling system (see chap. Current care and maintenance). Remove the decorative cover of the power unit and remove the spark plug / plug. Turning the engine at the central bolt of the crankshaft in the normal direction, bring the piston of the cylinder to be tested in the position of TDC, and then connect to the appropriate spark plug hole special tester, previously calibrate it - act in strict accordance with the enclosed instructions. Remove the filler cap of the motor oil (see chap. Current care and maintenance). Apply the compressed air into the cylinder and the speed of the meter vote collapse. Result record. If you check the crankshaft begins to rotate, take care of his blocking. Repeat the test for the remaining cylinders, - act in the order of ignition (see chap. Systems of an electric motor). Disconnect the gauge, screw the spark plug / bulbs and replace the decorative cover of the engine. Compare the test results with the requirements of the Specifications Chapter Engine. If necessary, make necessary regenerative repair.

Checking the cylinder bores using a special lamp probe