I've heard about this but can anyone enlighten me as to what exactly this fault is, and the ramifications of a bolt failure? Anyone experienced this?
yes - i'm sure more will be along to fill in all gaps but it only affects the larger 904 cc type and early models only as it was cured with a better spec material later on but I don't know the cut-off year. There is a reference to the later stud Part Number somewhere on here or if not then .ms Forum. The problem nearly always targets the front cylinder as its more prone to picking up corrosion and hence testing the studs more to their limit when tightened/loosened repeatedly.
Hi, the early 1990 / 91 904 motors had poor quality and thin cylinder head studs fitted during production. In essence because of the high compression of these engines they would fracture and split causing a loss of compression at the least or if all four on one cylinder failed at the same time the head and sometimes the barrel would separate from the case. The fault usually showed itself on the left side of the engine, opposite side to the belts, although this was not always the case. Not an expensive failure, more of a faff removing the broken stud (s) from the crankcase which required removal of the head and cylinder. In addition its usual to replace all 8 with the upgraded studs on one hit, hence the engine would require removal from the frame to gain access to the rear cylinder gubbins. If the studs pop it will be clear they have gone as there will be a massive loss of power. The upgraded head bolts are black in colour over the original silver / natural metal colour of the original stud.
notes on above - most often the first time they fail is when someone attempts to undo a cylinder head nut - any of the four/all of the four can fail - one broken stud can go undetected for some time on an otherwise sound engine.. good reference stuff here :- http://www.google.co.uk/url?sa=t&rc...bJ7hB1eqZlUKzgg&bvm=bv.62922401,d.ZG4&cad=rja and here :- Broken Head Bolt Question - ducati.org forum | the home for ducati owners and enthusiasts
