The brief
The Golf had crossed 120,000 km with a faint ticking from the front of the engine and the odd hard cold start in the morning. Two early signs that the timing system was ageing past its service life. The owner brought it in before anything actually let go.
The timing belt keeps the top of the engine spinning in step with the bottom, and on this engine it also drives the water pump. It's a service item with a set life, and when it's old the rubber glazes and the tensioner and idler bearings start to wear, which is the ticking, and a tired belt can let the timing drift a touch, which is the awkward cold start. On this kind of engine a belt that lets go takes the valves with it, so it's a job you do on time, not after.
The diagnosis
With the covers off, the belt's ribbed face was glazed and showing fine surface cracks, exactly what an old belt looks like. The tensioner had play in its bearing, a wobble it shouldn't have. And the water pump, which this belt drives, was just starting to weep at its shaft seal.
So the belt wasn't the only tired part in there. Changing it alone would have left a worn tensioner and a leaking pump behind the new belt, ready to be the next problem, so it was a full kit, all of it together.
The work
The timing was locked with the proper VAG tools so nothing could move, and the old belt, tensioner, idler pulleys and water pump all came off. A new VAG-spec timing kit went in, belt, tensioner, idlers and pump, the timing set back to spec on the tools, and the cooling system refilled with the correct coolant.
Then the engine was run through a warm-up cycle to confirm the belt drive was silent and the pump was dry.
A road test confirmed the ticking was gone and it cranked normally cold.
The outcome
Clean timing reset, a dry water pump, a silent belt drive through the rev range, no ticking, and normal cold cranking.
The Golf went home good for the next belt interval. A timing belt gives you no second chance if it snaps, so doing the whole kit on schedule, while it was still just a ticking noise, is the cheap insurance against a bent-valve engine.
