Audi Repair Questions? Ask a Mechanic for Answers ASAP
It's possible that either you have a leak in the system, which allows the coolant to boil (it should be able to hold pressure and keep from boiling, like a pressure cooker) or your coolant pump has failed. You can take the small return hose off the coolant bottle, point it into the top of bottle, and rev the engine to about 2000rpm. You should have constant flow, and not a lot of air or spitting.
Hi and thanks for requesting me. If the engine overheats in about 10 minuets of operation and the fan does not come on, the thermostat is stuck shut. The fans don't come on because there is no coolant flow past the fan sensor in the lower radiator hose. If you check the temperature of the lower radiator hose you can confirm that it is quite a bit cooler than the upper.