Cambelt change
I recently carried out a cambelt swap on my wife’s 2002 Ford Focus 1.6 petrol as it had done 145,000 miles on a replacement scrapper engine fitted at 72,000 miles due to bore wear causing blue smoke. I replaced the clutch as well, but had trouble undoing the crankshaft pulley nut despite having welded a tool to hold the pulley still and using a 1.5 metre pipe on the end of the socket bar. I ended up grinding off the head of the nut, damaging the pulley in the process, but that was not so much of a blow when I discovered part at the rear of the pulley was missing and, by the look of the crack, had been gone for some time. Anyway, I used the correct timing tools to set the timing and the car is running fine.
I know the crank pulley is tightened to 45Nm and then 90° further (which is very tight). The Haynes manual says the pulley fits on a taper on the shaft, but I used digital calipers to measure the taper and I could not find one – in my experience, timing pulleys are locked by a woodruff key as well as having a significant taper. So how does the pulley stay locked to the crankshaft? The same question applies to the camshaft sprockets. When I removed all three nuts from the crank pulley and camshaft sprockets on disassembly, they all pulled off by hand without a puller, whereas any tapered shaft fitting usually requires a puller to break the very tight fit. Steve Forsyth
A As you have discovered, the crankshaft pulley does not sit on a taper but on a perfectly ground parallel shaft. The system does seem precarious and relies purely on the friction of the clamping action between the bolt and the lip of the crankshaft.
The fitting instructions specify that the crankshaft should be cleaned to ensure that, when the pulley is fitted, it spins freely. The advantage of this system is that the timing will be very precisely set. With the camshafts and crankshaft locked into place and the belt fitted and tensioned before clamping up the pulleys, any slight deviation in the timing belt length will be accommodated. The crankshaft pulley bolt should always be replaced to ensure that the new bolt is exerting the correct force on the pulley to hold it in place. The crankshaft should be held in position when tightening the pulley using the tools 303-393A (plate) and 303-393-02 (locking adapter) to lock the flywheel.