i have a 97 318 i,bleed radiator,new waterpump,new belts,new thermo,engine cleaner,and block sealer.one bolt broke off in the block.was going to extract it but it doesnt seem to leak.using 10 w 40 because of higher miles.If anyone has any ideas it would help.seems to be building up to much pressure and steams out of cap.

was wondering if it would be the screw in block but it does not leak?