Hello, I've just bought a '97 A6 Quattro Sedan with high mileages (210k) that was sitting for like a year because the car did not passed CA smog and previous owner didn’t wanted to fix it, well I saw a lot of potential and buy the car put fresh gas and drive it home, the car drives real nice without any problems, engine is very strong and transmission shifts smooth without slipping, park it home and let it rest for 3 days.
I took the car to the office one day because it was raining very badly and my ’94 90S is not Quattro in the morning I made it without any problems and the Quattro worked great! but when driving back, at very slow speed I noticed a kind of bump like it had a broken axle or trying to engage 4x4 but picking up speed there was no issues, got home and let it rest but I saw water on the floor at the driver’s side so I let it dry for 2 days, took the car for a 10 mile drive and suddenly the bump got back but this time harder like it wanted to lock the front wheels it made it back home very slow, checked the axles and they are fine took out some transmission oil and does not smell burned and did not felt any metal debris in my fingertips but I have not opened the oil pan yet; do you think this is some electrical issues like TCM got wet or probably a mechanical issue with the transmission? There was no indicator that the tranny was failing and the shifter does not show that is on limp mode. Can someone help?

 

Update: I've found the leak (next to the engine fuse box) and it seems this is a regular leak because I found the same on my '94 90S put black silicon on it and now is sealed, cleaned the relays below the dash and at the very bottom I've found a relay with rusted connections that I've cleaned with a mesh brush and some WD40, replaced a blown 10amp fuse and took the car for a spin and its working fine now. I've contacted the previous owner and he told me this happened to him but the mechanic told him that the tires were different size and caused this failure (I was driving the car with a spare tire in the back and bought a new one) maybe this had something to do with it but now I'm happy because the car is working fine now. If someone had going thought this same problem I'll like to know how it was fixed. Thanks.