My 1.6 tdi (Jetta) has developed a slow coolant leak in the last 15,000 ks- leaks down to the warning light alarm every 5,000 ks (?) approx.
On inspection at 180000 k service by VW workshop, a small leak was found where the waterpump is situated.
I'm carrying it till the next sevice when timing belt and waterpump will be changed, just watching and topping up when required.
Not a 103 tdi but a 77tdi. Don't5 know the differences .
Refards