The brief
Jeremy brought his A3 in for its maintenance service, and the routine inspection turned up a coolant leak, the hoses on the cooling system perished and weeping. Two jobs in one visit: the service, and renewing the worn hoses before the leak got worse and the engine overheated. A service runs through the whole car, and the wear-and-tear check is what catches things like this. The cooling system uses rubber and fibre-reinforced hoses to carry coolant around the engine, and over the years the rubber hardens, the reinforcement degrades, and the hoses crack and weep at the bends and the clamp ends. A perished coolant hose doesn't reseal, and a slow leak becomes an overheat, so the worn hoses needed replacing.
The diagnosis
The service check and a pressure test on the cooling system pinned it: a couple of the coolant hoses were perished and weeping, hardened and cracking, losing pressure slowly. The radiator, the water pump, the expansion tank and the rest of the system held fine. The routine service items, oil, filters, fluids, were due alongside. So it was a service plus a coolant hose replacement: the wear items refreshed, the perished hoses renewed, the system bled and pressure tested.
The work
The engine oil and filter were changed, the air and cabin filters replaced, the fluids topped. The cooling system was drained enough to get at the hoses, the perished coolant hoses removed, and new genuine VW-spec hoses fitted with new clamps, the connections checked. The system was refilled with the correct coolant, the air bled out the proper way, and pressure tested to confirm it held with no weep. A road test confirmed a clean start, steady running, the gauge sat steady with no overheating, and the coolant level held.
The outcome
A clean bill of health on the A3, fresh oil and filters, fluids topped, the coolant leak sorted on fresh hoses, and the gauge steady. The car went home serviced and the cooling system tight again. Catching the perished hoses during the service caught the leak before it became an overheat, so doing it with the maintenance kept it to one visit.
