2001 astra van 17 tdi replaceing core plug?

obviously you will have to remove anything which is obstructing access,drain coolant,try a small chisel through the middle of it to lever it out,clean surrounding edges and try a small bit of appropriate sealer round the edge to help seal the system.If it was rotten then your coolant system may have been run without a/freeze so top up with a 50/50 mix,good luck

cdc
February 2013