Audi 80 Quiz
Cooling System

Cooling System Leak Check

In this manual: Cooling System
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

Leaks in the cooling system are easiest to locate with a hot engine, when the cooling system is under operating pressure. In this case, gloves are essential when checking the hoses to prevent burns.


Check the radiator and engine hoses, including the heater hoses, for leaks.
Check the hoses for cracks. Squeeze them to determine their condition. If they are hard, replace them immediately.

Squeezing the hoses can also reveal damage caused by rodent bites.

Check how far the hose ends extend onto the connections.
Check that the hose clamp bolts are tight.
Corroded clamps may suddenly fail during driving at full operating pressure. Replace them.
The workshop checks the cooling system for leaks using a manually operated air pump with a pressure gauge.

Fit this tester to the expansion tank opening and pressurize the system to 1 bar.

If the pressure does not drop within 1–2 minutes, the cooling system is considered leak-free.

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