Audi 80 Quiz
Cooling System

Thermostat Testing

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

Using a candy thermometer, you can check whether the coolant regulator opens at the specified temperature.

Opening begins Fully open Valve lift
approximately 87°C approximately 102°C 7—8 mm

PROCEDURE

Remove the thermostat.

Suspend the thermostat in a pot of water and heat the water.

Check whether the valve plate lifts off the seat at 87°C.

It is impossible to achieve full opening during this test (water in an open pot boils at 100°C, as is known), but at least you can see whether the thermostat opens further.

The full valve lift is thus almost reached. What can be seen is sufficient to determine whether the thermostat is serviceable or faulty.

Test yourself

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