Audi 80 Quiz
Engines

Compression pressure too low

In this manual: Engines
Technical Description — 39Engines — 41Exhaust System — 13Cooling System — 28Fuel tank and fuel pump — 12Air Filter and Intake Ducts — 13Mono-Motronic Injection System — 18Digifant Injection System — 19KE-III-Jetronic Injection System — 35MPI and MPFI Injection Systems — 32Clutch — 11Transmission and Driveline — 21Suspension and Steering — 33Brake System — 41Anti-lock brake system — 8Wheels and Tires — 13Body Electrical System — 35Ignition System — 24Lighting — 14Signaling Devices — 7Instruments and Auxiliary Equipment — 54Heating and Ventilation — 7Body Components — 18Troubleshooting — 6Specifications — 13
~1min read

Uniformly low compression pressure is not necessarily a cause for alarm; the readings may also be affected by measuring tolerances of the various test instruments. However, consider the problem if the difference between individual cylinder readings exceeds 2–3 bar. This may indicate:

Wear of pistons and piston rings.

Piston rings stuck in their grooves due to deposits.

Scoring (ovality) in the cylinders as a result of piston seizure.

Deposits on valve stems or valve seats caused by combustion residue or oil.

Burnt valves. In most cases, valves that do not seal properly are the cause of insufficient compression pressure and, therefore, reduced engine power. The only remedy is a cylinder head overhaul.

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A quick Audi 80 quiz: every answer comes with an explanation and a link to the manual page.