Where is the coolant drain port on the Passat?

[RuthRose]

The coolant drain port on the Passat is located on the left side of the engine compartment, above the shock absorber. The method for replacing the coolant is as follows: Before completely replacing the coolant, conduct a thorough inspection to check for any signs of leakage or cracks in all the pipes, with special attention to the five-way hose. The five-way hose gets its name from having five connection interfaces to various parts. The coolant flows through the five-way hose and is then distributed to different parts of the car to perform its function. If there is any coolant leakage in this area, replace the hose or re-secure the connection as needed. Drain the old coolant, then flush the liquid channels with clean water. Add clean water to the coolant reservoir and continue filling it with water until the water flows continuously through the engine cooling system. Then, start the engine and let it idle for 3 to 5 minutes to circulate the water. Initially, the water flowing out of the reservoir will have a faint pink color. Continue adding clean water until the water coming out is clear. Note: Don’t forget to remove the heater hose and drain the water from the heater core. After draining for about an hour, add the new coolant through the radiator hose. This allows the coolant to flow quickly into the radiator. Then, add another bottle of coolant to the reservoir until it is nearly full. Start the engine and let it run for about 10 minutes. At this point, the coolant level will drop slightly as air is purged from the cooling system. Add more coolant until the level reaches the "MAXT" mark on the reservoir.

[VonJune]

I remember helping my dad replace the coolant in his old Passat last year. The drain outlet was located at the bottom right corner of the radiator. You had to crouch down to see it—it was a plastic knob with a cross-shaped groove, darker in color than the radiator. Important reminder, repeated three times: Operate when the engine is cold! Operate when the engine is cold! Operate when the engine is cold! Last time, our neighbor Lao Wang opened it while the engine was hot, and the boiling liquid that spurted out nearly scalded his skin off. Before unscrewing it, lay out a drain pan and keep two buckets of clean water ready for rinsing. Also, for models after the B6, you’ll need to remove the engine undercover. The clips on the undercover are particularly brittle, so it’s recommended to use a dedicated pry tool instead of forcing it with a screwdriver.

[SanAngelina]

The coolant drain ports on Volkswagen models are quite user-unfriendly. On the Passat B5, it's a plastic plug at the lower left corner of the radiator. For B7/B8 models, it's relocated behind the engine. Shine a flashlight below the exhaust manifold to find a black plastic nozzle with a pressure relief groove. Pro tip: Keep a 10mm socket ready to remove the undercover and prepare a basin for waste fluid (toxic - don't pour down the drain). If you can't locate it, check page 192 of the manual for an exploded diagram. After replacement, remember to bleed the system - start the engine, set the heater to maximum, and top up coolant only after temperature reaches 90°C.

[Mendoza]

Just finished dealing with this issue on the 2017 Passat. The drain valve is located at the lower right corner of the radiator, blocked by the AC pipe. Tip: Use your phone to record with flash light extended inside. Don't randomly choose tools! You must use a Hazet 456 wrench - ordinary wrenches will scratch the radiator fins. During operation, unplug the water level sensor connector (the blue-green one), otherwise the fluid level alarm will keep sounding. For new coolant, purchase G12E or G13 specification - mixing will cause gel formation. Key point: After refilling, idle for 10 minutes and repeatedly squeeze the upper hose to bleed air bubbles.