Q: Crack in coolant reservoir

Hello! That is a common issue with Audi Quattro models. The plastic tank holds the pressure of the coolant system. The reservoir is located right above the engine. Of course the engine gets hot and hot air rises so the heat is transferred to the plastic of the coolant reservoir. Heat will weaken plastic and make it more likely to crack under the pressure of the coolant system. There are hoses connected to the reservoir which will harden from heat exposure. I suggest inspecting the hoses with the reservoir because the hoses and reservoir usually develops cracks consecutively. Driving an overheating vehicle can be fatal to an engines internal components. To eliminate the possibility of incurring more damage, I suggest having the overheating vehicle serviced by a mobile mechanic, such as one from YourMechanic.