VW Sharan Transmission Grinding + Coolant Link Revealed

Had the same issue on a VW Touran 2004 diesel. The symptoms match exactly what happened, rough shifting, grinding, warning lights, and limp mode activation. The root cause was a failed oil cooler causing cross-contamination between the cooling system and transmission fluid. This triggered the transmission protection mode. When the oil cooler fails, it allows engine coolant to mix with the transmission fluid, leading to erratic shifting and potential transmission damage. Key checks to perform: Check transmission fluid color and level, Look for coolant loss or contamination, Monitor engine and transmission temperature, Test oil cooler pressure This requires specialized diagnostic equipment to properly assess. The repair involves replacing the oil cooler assembly and complete fluid exchange for both systems. If caught early, transmission damage can be prevented. This is considered a serious issue that should be addressed immediately to avoid permanent transmission failure. The repair needs to be done by a transmission specialist with proper pressure gauge testing equipment and system flushing capabilities. Based on the symptoms described, would strongly recommend having the cooling system and oil cooler inspected before continuing to drive the vehicle. Car overheating and transmission failure often follow if left unaddressed.

Thanks for sharing your experience. The symptoms you described with your Touran perfectly match what happened to my Sharan. A faulty pressure sensor on my oil cooler also caused similar transmission issues last year. I ended up getting the cooling system inspected and replaced the oil cooler along with a complete fluid flush. The radiator repair shop also found a minor coolant leak they fixed while doing the work. Just curious, do you remember roughly how much you paid for the complete repair? Also, has everything been working properly since the fix or did you notice any other issues popping up?

Thanks for the update. After my previous oil cooler troubles, I got the pressure sensor issue fixed last month. The problem was traced to a faulty connection in the radiator oil pressure monitoring system. The repair was straightforward, just 95€ to replace the wiring connector. Since the pressure sensor repair, the transmission has been shifting smoothly with no warning lights or emergency mode activations. The leak detection tests showed the coolant system is maintaining proper pressure now. It was much cheaper than I initially feared, especially compared to potential transmission damage if left unfixed. The key was catching the pressure sensor malfunction early before it could cause more serious issues with the cooling system or transmission. Make sure to keep monitoring your coolant levels and transmission performance even after repairs. A properly working pressure gauge and cooling system are critical for preventing future transmission problems.

Thanks everyone for the helpful replies. Just wanted to share how my repair went in case others face similar issues. Took it to a transmission specialist who ran leak detection tests. They found the oil cooler was failing and causing transmission fluid contamination. The pressure sensor wiring also needed replacing. Total bill came to 650€ including: New oil cooler assembly, Complete fluid flush, Pressure sensor replacement, Radiator coolant system inspection Been driving for 2 weeks now and the transmission shifts perfectly. No more grinding or warning lights. The radiator repair shop did great work compared to my previous mechanic. Definitely worth getting it fixed properly by specialists with the right diagnostic equipment. Catching these cooling system issues early saved me from major transmission damage.