why do camfollwers break on my astra deisel 1.7 GM engine (1995)?

The camfollowers keep breaking on my astra deisel estate. It was ok for years but I have had 3 break in 6000 miles.
gerald c, May 2007


done
possibly valve timing is out, is critical , pistons can touch valves and break followers if not set correctly.

k, May 2007