torque down head bolts HELP

[russ22]

I am putting a head on a seadoo 4 - tec 260ph motor
The manual says to torque the head bolts to 40nm + 120 deg + 90deg
I torque the bolts to 40nm then I torque them a further 120 degs I then did 2 x bolts at 90 degs but on the 3rd bolts as I got to 30 degs the bolt seem to let go it suddenly became quite easy to turn
The 4th bolt was ok but the same thing happened to the next 2 bolts that I torque down
What do I do now if I undo the bolts then I have to throw them away and buy new ones
But I think the bolts have failed and have stretched past their yield point, but how do I tell with out pulling them out
any body have any ideas

Thanks

 

[gazzaskirepair]

Sounds like your block cylinder head bolt threads were dirty or had damaged threads

 

[russ22]

these were brand new bolts straight out of a sealed package dipped in oil and into the head you could not get them any cleaner
the bolt threads were cleaned

 

[skiasylum]

I found one reference on the Green hulk forum of Sea-Doo 4tec head bolts losing torque on the last 90 tighten. No reason why or what happen just that if you take one out at a time and retorque to spec you don’t have to replace head gasket. There was mention of reusing the old bolts where the new one failed.

 

[Greg Moore]

measure them when you take them out.. can't remember the spec but there is a spec on max stretched length to reuse.
Are these OEM or aftermarket?