Audi 100/A6

1990-1997 of release

Repair and car operation

3.1.1.4. Compression check

THE GENERAL DATA

If the engine works badly or with faults, check up system of ignition and fuel system. If it was not possible to find the reason of bad work of the engine, inspect a compression. Regular carrying out of this check will allow you to warn occurrence of malfunctions in advance also.

For carrying out of check the engine should be разогрет, the accumulator should be charged, and spark plugs should be unscrewed.

PERFORMANCE ORDER

1. Disconnect ignition system, having disconnected a wire of a high voltage of the coil of ignition from a cover of the distributor of ignition. Earth a wire on the block of cylinders. 2. Connect the device for compression measurement to an aperture of a spark plug of cylinder N1. 3. Completely open throttle заслонку and scroll a cranked shaft of the engine a starter. After one or two turns pressure of compression should raise to the maximum mark, and then be stabilised. Write down the received result. 4. Spend similar check with other cylinders and write down the received indications. 5. Pressure in all cylinders should be identical. The difference more than in 2 bar between any two cylinders means malfunction. In the serviceable engine pressure should accrue quickly. The small pressure of the first step gradually raising at the subsequent steps, specifies that piston rings are worn out. Small pressure of the first step which does not accrue at the subsequent steps, specifies in leak in valves or on the punched lining of a head. Adjournment on the bottom parts of valves can become the reason of a low compression also. 6. If at carrying out of check you have doubts, address to experts. 7. If pressure, in what or the cylinder too low, spend the following check to establish the reason. Pour in a teaspoon of pure engine oil in the cylinder through an aperture of a spark plug and repeat pressure check. 8. If after addition of oil pressure of compression has increased, it means that the piston or the cylinder is worn out. If pressure has not increased, means, the reason in the worn out or scorched valves or in the punched lining of a head of cylinders. 9. Low pressure in two next cylinders practically always means that between them the head lining is punched. 10. If in one of cylinders pressure approximately on 20 % more low, than in the others, and the engine badly idles, it means that the reason, probably, the worn out cam of a camshaft is. 11. After check end screw in spark plugs on places and connect ignition system.