Land Rover Repair: 1999 4.6 Range Rover, losing coolant, head gaskets

Question
recent r/r of head gasket (less than 200 miles ago)& am now losing coolant and vehicle is overheating. What could be the problem?

Answer
The first explanation, which I'm sure you've considered, is that you did something wrong in the head gasket job.

Failing that, I'd say the head gaskets were a false trail, and you have a liner failure within the engine block.  If you originally replaced the head gaskets in response to an overheat situation, and now you still have it, odds are 99 to 1 this is your problem.