This can depend on many things. First what kind of eng and what year are you working with. as far as the injection lines where are they breaking? at the flange end inside the nut or in the middle of the line? If it is under the nut over torque on the nut can cause this. also during removal and torque of nut, nut and line can bind causing line to twist reducing integrity in high pressure line and eventually causing cracks. one other thing is excessive or high frequency vibrations in eng. these types of vibrations can potentially be caused by a failed vibration dampner on the front of the crankshaft mounted behind the crank pulley. Your lower radiator hose should be colder than your upper radiator hose by at least 10-15 deg min But not cold after eng has warmed up to operating temp. Is the vehicle overheating? Does the eng run Cold? both problmes can be caused by a stuck thermostat in either direction. Much more info needed to more accuratly diagnose problems, hope this helps a little
crccastellanos
April 2009