VW Tiguan Coolant Mystery: Hidden Leak Warning Signs

Had a similar situation with my 2011 VW Touareg TDI. The coolant reservoir was losing fluid but no visible leaks. After thorough inspection, found air pockets forming in the cooling system due to a failing water pump and damaged radiator cap seal. The check engine light in these VW diesels often triggers when the coolant level drops below a certain point. This can indicate several potential issues: 1. Failing water pump seals 2. Cracked coolant reservoir 3. Loose or damaged hose connections 4. Faulty radiator cap not maintaining proper pressure 5. Cooling fan control module issues The most concerning scenario would be coolant mixing with engine oil, indicating a possible head gasket problem. This was a serious repair in my case, requiring complete water pump replacement and cooling system flush. Key warning signs to watch for: Sweet smell from engine bay, White exhaust smoke, Engine overheating during normal driving, Coolant disappearing without visible leaks Recommend getting a pressure test of the cooling system. The cooling system in these VW diesels is complex and interconnected, best to address issues early before they cause major engine damage.

Thanks for sharing your experience with the Touareg. My water pump and head gasket both needed replacing on my Tiguan last year. Problem started exactly the same way, coolant mysteriously disappearing and engine overheating warnings. How much did the repair cost you in total? Just wondering if prices have changed much since then. Also curious if you had any other cooling system issues pop up after the initial fix?

After my initial post about the Touareg cooling issues, I went to a certified VW specialist. The good news is my current problem turned out to be much simpler than my previous water pump troubles. The mechanic found a loose cable connection affecting the coolant level sensor, which was causing false readings and the check engine light. Total repair cost was just 95€ to fix the faulty sensor connection, way less than I feared after my previous cooling system overhaul. The coolant level is now stable and the warning light has stayed off. Since fixing the radiator hoses and water pump last year, I haven't had any additional cooling system problems. Regular pressure tests show the system is maintaining proper circulation without any air pockets. The new radiator cap is doing its job keeping the correct pressure, and there are no signs of coolant leaks. My suggestion would be to get regular cooling system checks even when everything seems fine. Much cheaper than waiting for major component failures like we both experienced with our earlier repairs.

Thanks for the advice. I took my Tiguan to a new certified mechanic this week. They found the coolant was leaking from a cracked radiator hose near the water pump connection. The cooling fan was also showing signs of wear. Total bill came to 320€ for replacing both radiator hoses and the cooling fan assembly. Much better than I expected after my previous costly head gasket repair. The coolant reservoir is now maintaining proper level and the check engine light has cleared. The mechanic did a thorough pressure test of the entire cooling system to confirm there were no other leaks. They also flushed and refilled the system with the correct VW-spec coolant. Everything is running smoothly now with no overheating warnings. Going forward, I will be doing regular cooling system maintenance to avoid any major issues like before. Really glad I caught this early before it led to more serious engine problems.