Ford Fiesta
Part two: The first major job on our latest project vehicle is to replace the cambelt.
As long as they are simple to change, cambelts are a better proposition than chains. The 1250 Yamaha Duratec engine in our 2009 Ford Fiesta Mk7 project is based closely on the unit we first saw in 1994 and cambelt technology means that Ford specify a change point at 100,000 miles or 10 years, even though the Haynes manual recommends a change at 62,000. It wasn’t long ago that an entire engine was pretty tired by 100,000 miles and the belt needed doing every 20,000 miles.
So it was with some nervousness that we drove the car to Parkside Autos in Worksop to assess the state of the belt. Turned out it was still good: shiny on the outside, with the teeth showing little sign of distress and the tensioner roller still turning smoothly. Impressive for 100,000 miles. Even so, it’s worth changing the belt, tensioner and water pump every 60,000 miles regardless of condition, to be on the safe side.
Just a few words on the 1242cc and 1388cc belt layout. The engines are 16-valve twin-cam units and the belt run is around the crank sprocket, a spring-loaded self-adjusting tensioner, two cam sprockets and back again. Locking tools are required because the cam and crank sprockets are a friction fit rather than keyed on and require the torque of the bolts to secure them.
In theory, you could remove the old belt, time the crank at Top Dead Centre (TDC) with a dial gauge down number 1 spark plug hole (check this before the old belt comes off ) and slip on a new belt. Chances are the timing would be correct or so close that it made no difference. But the idea of the freewheeling sprockets (or pulleys) is that the crank and cams are timed up and locked, the belt is fitted, the tensioner released and the three sprockets find their own position before the bolts are tightened. Guaranteed perfect timing.
On this engine, the water pump sensibly has nothing to do with the cambelt drive or tension. Instead, it’s driven by the auxiliary belt, which is an elastic type. That means the belt can stretch slightly, doing away with the need for a tensioner. This keeps things simple.