I have a Suzuki Grand Vitara year 2001(01) it runs perfectly OK, but it keeps losing water. It does not over-heat and the gauge never goes above half way. I have taken it to a garage to have the system pressurised, and he said it was OK. The only comment he made was the expansion bottle cap was worn, so I replaced it. The one that was on there was 1.1 psi and the one i was sold was 0.9 psi; it helped a bit but there is still a problem. Can you suggest anything? The car is a 2ltr diesel.