take the glow plug out with a 4 way wrech that has sockets around it make sure the inside of your cooling head is clean and just loosen it and take it out and stick the glow plug in the glow enigher and it should be bright red if it isnt than its bad also make sure you screw the glow plug in stright and tighten it dont overtighen it though,also what really helps is getting a glow enigher that has a meter on it