why do head studs pull out?

[vwvanman0]

hi,wondering why studs pull out of the case,is it heat or something else?

 

[Araon]

pulling out, ****** threads

 

[Clarkson46]

Over tightened head bolts!

 

[vwvanman0]

na properly torqued,rebuilt engine done 500 miles and theyve pulled again,had case savers put in,not looked yet if the savers out of the case or the studs out of the case saver,studs pulled on different heads to last time tho,its a 1641 in a pickup with the correct tin and seal round the engine bay.
is it likely to be down to the case,fatigued or misaligned or will it be getting overly hot?

when i bought it there was a 1600 in with a beetle over gearbox panel,ie you could see through to the driveshafts,thought i was being smarty pants putting the correct tin on,now im thinking about it with the poor side vents maybe it would have been better leaving it!

 

[Loxy]

There are different torques for 8mm & 10mm head studs 18ft/lb & 23 ft/lb from memory, are you using the wrong one?
& is the correct sequence being used to torque heads up ? you are supposed to use a different order & gradually up the torques.

 

[Clarkson46]

WHS^^^^^

 

[mk2matt]

i had the same prob with head studs pulling out

the place i got my engine rebuilt done a crap job and the studs were cross threaded

lucky my mate olly at beetle magic sorted it and and put bigger studs in with some threaded stuff(sorry cant remember what they were called)

it all can be sorted dude anyway