Whilst fitting a new water pump in my just finished Haynes Roadster I removed the cam belt on my Ford Sierra 1991 1.8L CVH engine. When reassembling the cam pulley sprocket slipped out of my special tools grasp and rotated from 12 O'clock to about '10mins past 12'. Rightly or wrongly, I simply rotated it back to upright and tightened the bolt then fitted the cam belt. Now I wonder if I have left the valves out of sequence. The engine runs fine but there is more plinking noise under the cam cover than I remember. Have I made a big error? Do i need to take it all off again and realign the cam shaft, and if so how shall I do it?

Advice from the experts greatly received - Thanks

When it slipped and you turned it back (no harm should be done doing that) did you check the timing marks were aligned on crank and cam sproket? Crank at TDC mark and pointer on cam in line with pip in head?

Yes I turned back the cam sprocket to line up with the mark on engine. The crankshaft sprocket was always at top dead centre. When I put belt back on both pulleys were correctly aligned.

I had wondered if when the cam slipped round it would move the valves and by turning back the cam sprocket I may have left a valve in the wrong position. However if reversing the cam sprocket reverses any valve movement that had been created, then presumably I am OK?

Did you turn the crank 2 revs and recheck timing and tension after?

yes I did that and it rotated smoothly and I checked the tension on longest run of belt with it set at 60 degrees before top dead centres as per Haynes manual.