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Compression check in cylinders
Compression (pressure at the end of the compression stroke) in the cylinders - a key indicator for the diagnosis of the condition of the engine without disassembling. According to its average value and the difference in the values of individual cylinders can reliably determine the degree of general wear and tear connecting rod and piston engine trouble and identify this group and valve train parts. Check the compression of a special device - Compression, which now can be easily obtained in large auto parts stores.
NOTE It looks like compressometer used to illustrate the book. There are options for Compression, which replace the rubber tip that when testing compression simply strongly pressed against the spark plug hole, set the threaded fitting for screwing instead of spark plugs. |
A WARNING An important condition for correct readings when testing compression is a bad starter and electrical circuits, as well as a full battery charge. |
1. Start the engine and warm it up to normal operating temperature. |
| | 3. Remove the tips of the wires from spark plugs ... | 4. ... and turn out all the candles. |
| 5. Disconnect bundles of low-voltage wires from the ignition coil, thereby turning off the ignition system. |
A WARNING Cranking motor starter disconnected at the tips of high-voltage wires and ignition coils non-disabled can lead to breakdown of high voltage circuits. |
| | 6. Disconnect the wires from a fuel module. | 7. Install the compression gauge into the spark plug hole checked the cylinder and press it strongly. |
8. Press the accelerator pedal fully to fully open the throttle. |
9. Include a starter and turn them to the crankshaft of the engine as long as the pressure in the cylinder is no longer increasing. This corresponds to approximately four cycles of compression. |
NOTE For correct reading compressometer crankshaft must rotate at 180-200 min -1 or above but not exceeding 350 min -1. |
| 10. Writing compression tester readings, set the arrow to zero by pressing the air release valve. |
NOTE In a different design Compression readings can be reset by other means (in accordance with the instructions for use of the device). |
11. Repeat steps 7-10 for the other cylinders. The pressure should not be lower than 1.5 MPa and not be different in different cylinders over 0.15 MPa. The lowered compression in separate cylinders can result from a loose fit valves in the saddle, damaged cylinder head gasket, broken, or sticking piston rings. The lowered compression in all cylinders indicates wear of the piston rings. |
NOTE The nominal value of compression in the cylinders - 1.5 MPa (15 kg / m 2 with a) the maximum permissible - 1.4 MPa (14 kg / m 2 with). |
12. To clarify the reasons for the lack of compression fill the cylinder with low compression to about 20 m 3 of clean engine oil and re-measure compression. If the reading compressometer increased, most likely the fault of the piston rings. If the compression remains unchanged, then head valves are not flush against the seats or damaged cylinder head gasket. |
HELPFUL ADVICE The reason for the lack of compression can be determined in a compressed air cylinder, wherein the piston is pre-set in the compression stroke TDC. To do this, remove the tip of the compression tester and connect it to the compressor hose. Insert tip into the spark plug hole into the cylinder and apply air pressure of 0.2-0.3 MPa. to the crankshaft of the engine is not cranked, including higher transmission and brake the car a lay brake. The output (drain) of air through the throttle device indicates tightness of the intake valve and exhaust through - tightness of the exhaust valve. If damaged cylinder head gasket air will escape through the neck of the expansion tank in the form of bubbles or the neighboring cylinder, which is detected by the characteristic hissing sound. |
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