The brief
Tricia's A4 was getting through coolant, needing topping up far too often, and she was referred to us to have it checked. Coolant that disappears is leaking somewhere, and a leak that's left to run doesn't just lose coolant, it can do collateral damage, which is exactly what this one had done. The coolant pump circulates coolant around the engine, and as it ages it weeps from the shaft seal or the housing. That's a routine fix on its own. But this leak had been going for a long time, and the coolant had been dripping onto the cylinder head and corroding it, the tell-tale white powdery corrosion, until the head was past saving. So this wasn't just a pump, it was a pump and a head, because the prolonged leak had taken the head with it.
The diagnosis
The Audi specialists found the source straight away: the coolant pump leaking, which is the disappearing coolant. But the inspection also showed the damage, the prolonged leak had corroded the cylinder head, the white powdery corrosion plain to see, and the head had to be replaced. The rest of the engine was sound. That's a coolant pump replacement plus a cylinder head replacement, the leak fixed and the corroded head renewed, rather than a pump alone on a head that wouldn't seal.
The work
The leaking coolant pump was removed and a new genuine Audi-spec pump fitted with a fresh seal, and the corroded cylinder head replaced, the head gasket and the head bolts renewed, everything torqued to the manual figures in sequence. The cooling system was flushed, refilled with the correct Audi coolant, bled the proper way so no air pockets were left, and pressure tested. A road test confirmed the gauge sat steady, the engine warming up at the right rate, no coolant loss, and the system holding pressure.
The outcome
No more coolant loss, no top-ups, the level holding between checks, the gauge steady, and the system holding pressure on a fresh head. Tricia got the A4 back with the leak resolved and the corrosion damage repaired. The lesson is that a leaking coolant pump caught early is a small job, but left to drip on the head it becomes a big one, so this fix put both right and ended the distress.
