Turbo Steve
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All Volkswagen's use only one kind of antifreeze or coolant, no matter what engine propels them - gas or diesel. VW calls this red-colored coolant "G-12" and mixes all cars shipped to the U.S. with a 40% solution of antifreeze and those going to Canada get a 60% for better protection.
VW's G-12 Coolant is a similar substance to Prestone's 5/15 Extended Life or Havoline's Dex Cool.
All VW engines use an impeller-type waterpump that is mounted into the cylinder block that usually is belt-driven. In the case of the A-4 TDI engine, the waterpump is driven by the Timing Belt, further adding more stress to this part that needs replacement at regular intervals, as it also drives the Injection Pump and Valvetrain.
VW radiators are all cross-flow in design, with plastic side tanks and obviously an aluminum core assembly. The cooling system capacity of the (ALH) TDI engine is 6.3 quarts or 6.0 liters.
Thermostats control two radiator cooling fans via a thermoswitch located in the side of the radiator's plastic tanks. As the water temperature rises, the switch closes to start the electric fans in one of the two following stages:
____________
Radiator Fan Thermo-Switch Operating Temperatures
* Stage I - Low Speed
Switch on...............197* - 206*F (92* - 97*C)
Switch off..............183* - 195*F (84* - 91*C)
* Stage II - High Speed
Switch on...............210* - 221*F (99* - 105*C)
Switch off..............195* - 208*F (91* - 98*C
____________
Naturally, running the A/C will also activate the cooling fans as well.
The (ALH) TDI diesel engine uses a 195*F thermostat that actually starts to open at approximately 185*F (85*C) and is fully open by approximately 221*F (105*C), with the central spring-loaded butterfly valve traveling about 0.28" or 7mm from closed to fully opened.
Note: Key data listed above and pictures below are courtesy of RB's 2000 Jetta / Golf Repair Manual - Section 19.
[ August 04, 2001: Message edited by: Turbo Steve ]
VW's G-12 Coolant is a similar substance to Prestone's 5/15 Extended Life or Havoline's Dex Cool.
All VW engines use an impeller-type waterpump that is mounted into the cylinder block that usually is belt-driven. In the case of the A-4 TDI engine, the waterpump is driven by the Timing Belt, further adding more stress to this part that needs replacement at regular intervals, as it also drives the Injection Pump and Valvetrain.
VW radiators are all cross-flow in design, with plastic side tanks and obviously an aluminum core assembly. The cooling system capacity of the (ALH) TDI engine is 6.3 quarts or 6.0 liters.
Thermostats control two radiator cooling fans via a thermoswitch located in the side of the radiator's plastic tanks. As the water temperature rises, the switch closes to start the electric fans in one of the two following stages:
____________
Radiator Fan Thermo-Switch Operating Temperatures
* Stage I - Low Speed
Switch on...............197* - 206*F (92* - 97*C)
Switch off..............183* - 195*F (84* - 91*C)
* Stage II - High Speed
Switch on...............210* - 221*F (99* - 105*C)
Switch off..............195* - 208*F (91* - 98*C
____________
Naturally, running the A/C will also activate the cooling fans as well.
The (ALH) TDI diesel engine uses a 195*F thermostat that actually starts to open at approximately 185*F (85*C) and is fully open by approximately 221*F (105*C), with the central spring-loaded butterfly valve traveling about 0.28" or 7mm from closed to fully opened.
Note: Key data listed above and pictures below are courtesy of RB's 2000 Jetta / Golf Repair Manual - Section 19.
[ August 04, 2001: Message edited by: Turbo Steve ]