Ford Focus ST170
2.0L Duratec ST 16V naturally aspirated with 127 kW at 7,000 rpm — the first Focus ST, entirely without turbocharging. Equal-length stainless steel headers produce a distinctive, full-bodied resonant exhaust note. 85% of peak torque (196 Nm) available from 2,200 rpm — remarkably broad for a high-revving naturally aspirated unit. Above 5,000 rpm it comes alive, spinning to 7,350 rpm at the limiter. Mechanical bucket tappets instead of hydraulic — valve clearance check every 40,000 km recommended. Long-lived with consistent servicing: owners report over 177,000 km without issues.
The first Focus ST — naturally aspirated purity
No turbo crutch, no torque tsunami — just an engine that wants to rev. It wakes up above 5,000 rpm, delivering its maximum at the limiter at 7,000. Stainless steel exhaust headers produce a sound that can't be mistaken for any turbo engine. For those who appreciate unfiltered, honest power delivery.
Engine Weaknesses 9
The 1.8 Zetec-E is an interference engine requiring precise timing belt tension. Special tools are needed for correct installation; wrong positioning causes immediate power loss. Replacement every 100,000 km recommended.
Symptoms: Sudden engine cutout, power loss after timing belt change if incorrectly fitted, loud bang
The Duratec ST170 has particularly thin piston rings by design. Wrong oil or infrequent oil changes lead to premature wear.
Symptoms: Increased oil consumption at higher mileages; blue smoke under load; declining compression.
The dual ignition coil (coil pack) on the Zetec-E is prone to failure at high mileages. Misfires on cylinder 4 (P0304) are often the first sign. Replace ignition leads and plugs at the same time.
Symptoms: Misfires (fault code P030x), rough idle, power loss, fuel smell from exhaust
Same thermostat housing problem as the 1.6 Zetec-S: the plastic housing cracks from material fatigue. Affects the Ford Fiesta Mk5 and Puma with the 1.4 Zetec-S ALDA/ALDB.
Symptoms: Coolant loss without visible ground leak; temperature warning; coolant smell inside via heater.
The Duratec ST uses mechanical bucket tappets instead of hydraulic lash adjusters. With overdue oil changes or oil starvation, camshaft lobes and bucket tappets wear out. Valve clearance checks are mandatory at every major service.
Symptoms: Ticking from the valve train on cold start, clattering at warm idle in the upper rev range, increased oil consumption at advanced wear
Thermostats on the Zetec-E block are wear items. Permanently stuck in the cold-open position leads to increased fuel consumption and poor heater output. Replacement is straightforward and inexpensive.
Symptoms: Temperature gauge permanently low, barely any heat from heater, increased fuel consumption
The naturally-aspirated ST170 is sensitive to a dirty throttle body. Unlike the 130 PS version, values are harder to re-learn — cleaning with a re-learn procedure is recommended.
Symptoms: Rough idle, revs drop after starting, occasional stalling at idle
Like the 1.6 Zetec-S, the idle air control valve clogs from oil mist out of the crankcase breather. Cleaning is often enough; replacement is cheap.
Symptoms: Engine stumbles or stalls at idle; revs drop below 500 rpm when braking; warm-up hunting settles after a few kilometres.
Lambda sensors on the ST170 respond too slowly comparatively early. Mixture errors and misfire codes result. Sensor replacement under warranty needed as early as 25,000 km.
Symptoms: Lazy lambda sensor fault codes; rough idle; increased fuel consumption; occasional hesitation.
Vehicle Weaknesses 7
Sills and rear wheel arches rust from the inside out. Vehicles from approximately 150,000 km often have widespread corrosion. Always check with a magnet before buying.
Door lower edges and tailgate frequently show early rust spots, particularly at seal contact areas. Water collects in the folds and attacks the metal.
Water enters through a faulty windscreen seal on the passenger side. The pollen filter box can overflow and the passenger footwell carpet becomes wet. Risk of mould.
Rear brake callipers or drum brakes tend to seize, especially after extended periods standing. Brake discs and pads wear unevenly.
Door lock actuators fail frequently; doors lock and unlock sporadically. Plastic window regulator mechanism breaks; window sticks or drops into the door.
Anti-roll bar drop links and control arm bushes wear prematurely. Rear wheel bearings fail without visible play and only become noticeable through noise.
Window regulator motors fail frequently, often due to broken plastic in the drive mechanism. All four doors affected, especially the driver's side. Parts are cheap, but removal is time-consuming.
Reports & Tests
8129 owner complaints filed with NHTSA (1998–2004). Most reported: Electrical (2872), Engine & Cooling (943), Fuel System (818).