My Mondeo 1995/2.0i GHIA is leaking some coolant. This has occured after I had the cooling system rebuilt - new pump, new thermostat, new radiator. I've also had both pipes from the radiator replaced which cool the gearbox etc. so they are new also.

I've had it pressure tested and it doesn't leak under the test.

If I take it for a short drive e.g.15 miles, it doesn't leak coolant.

However, when I take it for a long drive and park it in the driveway later, I notice a puddle of coolant being deposited.

It basically randomly spits some coolant when it feels like it.

This equates to 400-500ml per week. My mechanic has no idea what it is.

Ideas?

Picture below shows where the leak is, there is a rubber pipe in that area and we've put 2 clips on it to make sure it's 100%. Still leaks unpredictably.