1995 Jeep Cherokee 2.5 turbo deisel

My 1995 Jeep Cerokee 2.5 Turbo Deisel has been losing coolant through the expansion tank cap and has needed topping up with a litre about every 100 miles. The temperature gauge does not show it is getting hot. I recently topped the oil up as it was getting low and since then it chugs and produces a lot of blue smoke for a few minutes after starting. After that it runs fine. There is no oil in the coolant or water in the oil and the water hoses do not feel presurised.