MJ Audi

I have had multiple issues with this Avant. I have Emmisions light/MIL in orange and can hear water sloshing/running behind the dash audi Multimedia centre. Strange noise whining when driving worse as you go faster.... Symptoms of temp gauge on car reads 90°, temp on my OBDII scanner states its 100° fans are working, coolant has been changed m, burped etc, no external leaks, no evidence of coolant going down. It's now been to 4 garages..paid for Disagnostics x4, as a women...all mechanics saying different things, they have said its fuel, new petrol cap, x 4 new coil packs, spark plugs, oil and filter, PCV, It's had new fuel rail, new PCV separator in 2021, spark plugs 12 months ago. Serviced.. I've changed MAP, Temp new sensors..I've reset the TPS... Oil cap is sucking on when engine starts which suggests PCV again ?? I have noticed oil stains down the back of the engine from cam cover Any ideas? Water pump? Thermostat? Main oil seal...intake leak?