Citroen C5 2.2hdi 03/2004 Hi All I have to replace my headgasket so i've removed the head ect,now i've come across a problem. When i checked the protrusion of the pistons,pistons 2 and 3 do not come above the top of the cylinder block.pistons 1 and 4 are both ok but 2 and 3 are 1.5mm - 1.8mm below the top of the block. Please please can anybody advise me of any reason this could happen and how to fix. Many many thanks Stuart