Broken Rocker Shafts

[Bangbourneman]

:( My 1996 tdi with 120000 on the clock has snapped 2, yes 2, rocker shafts in the past month/1000 miles. Has anyone any experience of this happening before and any advice? After the first one went, a new shaft was fitted, the rear stud replaced and the thread heli coiled but it went again but this time the centre stud but the shaft had snapped again. If anyone can help I'd really appreciate it cos me and the mechanic are stumped! Thanks

[Geobloke]

Holy moly thats bad luck! Have never heard of this happening before! sorry! :(

[imspanners]

I would suggest you get the timing checked, as broken rockers is usually caused by the piston catching the valve whilst it's still open and forcing it into the rocker.
Or is it over-revving because the Governor settings have been messed with?

Sorry just re-read the post and realised you mean the shaft not the rockers themselves. The above still applies to a certain extent, but it sounds like the shaft is being flexed, possibly not running true? Does it move freely, with the bolts partially torqued? Try removing one of the rocker shaft carriers at a time and partially torquing it back down, seeing if it makes a difference to movement.