ENGINE

It’s all about the engine. The source of the ST220’s grunt comes from its American-made Duratec-ST, an oversized lump of alloy that can mean death to a Mondeo if all goes wrong.

But that’s not to say it will, because 150,000 miles is usually nothing to worry about. Usually…

Crucially, listen for nasty knocking, beware of blue smoke or steam from the exhausts and steer well clear of any ST220 engine that doesn’t sound smooth. It’s possible that ticking noises could result from camshaft bearing caps or belt tensioners ( which are relatively minor fixes) but crippling issues could be lurking beneath. An owner selling a stuttering ST220 or a car with poor idle may claim it just needs a coil pack or spark plugs ( admittedly tricky to change the rear bank), but such symptoms also point to head gasket failure and an appointment with the scrap man.

Misfires, poor performance, rough idling and excessive fuel consumption could also be caused by the throttle position sensor, airflow meter, vacuum hoses ( perished pipes lead to induction issues) or ECU but you’ll need a thorough diagnosis to work out what’s wrong.

Oil leaks are pretty common, if not easy to solve. You’ll almost certainly see gunge around the front exhaust manifold, but chances are it’s dripped from the filler neck when being topped up.

Nothing is easy to access under the bonnet, thanks to the V6 engine originally being designed for rear-wheel- drive applications and squeezed into place beneath the Mondeo’s bonnet. This means a tendency for pipes, hoses and wires to chafe; the loom around the battery, bulkhead and alternator is especially prone.

Coolant leaks are potentially catastrophic, and it takes only a pinhole in one worn hose to result in total engine meltdown (the car in these photographs suffered that exact fate while still relatively new).

Fuel pump failure is also fairly common ( often at around 100,000 miles), resulting in non-starting. The fix involves dropping the tank, but many bodgers cut holes beneath the back seat to gain access.

Servicing is due every 12,500 miles but the timing chain should last the life of the engine. A rattling chain often signals the end of its life…