Constant Coolant Top up Needed - Why?

[tkroukamp]

Hello fellow forum members. I have a problem I was hoping you gurus may have an idea on.

I have a '99 Boxster 2.5 58K miles. About 6 months ago I had the water pump fail. I took it in to be looked at (not a genuine Porsche dealer), and they replaced the pump. I was told that they were having a hard time 'burping' the system and that there were air pockets that needed to flush out and it would happen in time. They told me to top it up with water and after a while it would be fine.
6 Months later and I'm still topping up coolant with about a pint every 100 miles or so.
I know what you're all thinking. There's a leak. Well that's what I thought, so when I took it back to be looked at again (after about 1500 miles), they told me they put pressure on the system and there are no leaks. I have never noticed any leaks on the garage floor either.

So anyone have any idea as to what may be happening? Where is the coolant going? Any help or advice would be most appreciated.

Thanks for looking
Tony