Also had guys loose glow plugs in the cylinder before from their mickey mouse push button switch. Most people do not understand that if it takes too long to start engine holding the button for 30 seconds will not change anything. The tips turn into a ballon and they will break off when you try to remove them ! If the tip broke off than the valve could have hit the plug tip and broke the rocker since there is zero room between the 2 items. It will mash it into the piston generally and eventually vaporize. Also check to make sure your timing marks are all lined up! Also if your balancer and crank sprocket are shot at the keyway than your timing will change around. This if not fixed will fu#$ up your crank!

Mike