Cooling system of a gasoline engine (Audi 80 B3)

System type - With sealed radiator and expansion tank, reliable belt-driven pump and electric fan controlled by a thermal switch.

The opening pressure of the valve in the expansion tank cap is 162 - 1.5 bar

Thermostat

Opening start:

• 4-cylinder engine - 85°C
• 5-cylinder engine - 87°C

Full disclosure:

• 4-cylinder engine - 105°C
• 5-cylinder engine - 102°C

Move (minimum):

• 4-cylinder engine - 7.0 mm
• 5-cylinder engine (10-valve) — 7.0 mm
• 5-cylinder engine (20-valve) — 8.0 mm

Electric fan

Thermal switch response temperatures:

Single speed fan (2-pin plug):

• Switch on - 92-97°C
• Switch off - 84-91°C

Two speed fan (3-pin plug):

• Switching on 1 speed - 92-97°C
• Speed 1 off - 84-91°C
• Switch on 2 speed - 99-105°C
• Switch off 2 speed - 91-98°C

Additional thermal switch (fuel injector cooling):

• Switch on - 110°C
• Shutdown - 103°C

Additional thermal switch relay (fuel injector cooling):

• Programmed time interval - 10-12 mm

Antifreeze

Type - Ethylene glycol with corrosion inhibitor (Duckhams Uruversal Antifreeze and Summmer Coolant)

Required concentration for protection against freezing at temperatures up to:

• -25°C — 40%
• -30°C — 45%
• -35°C — 50%

(This article was copied from the website AUDIMANUAL.RU)