Although 55,000 miles is low mileage, the 1.5s are fairly notorious for warping heads, blowing head gaskets, and having the blocks crack around the head bolt threads. I won't even replace a head gasket on one of them because the odds of it failing are high even if you do everything right. I would also mention that I have a 1.6TD short block for sale in the classifieds. It was completely rebuilt 50,000 miles ago with all new German parts (new bearings, oversize pistons, etc...).