I dont know the mk3 but on the mk 4 the correct coolant level in the expansion tank is quite low down . To the uninitiated the bottle may appear to be almost empty and the level line is not obvious because its much lower down than you might expect.
In these circumstances a previous owner ,or the car sales staff, might have topped the coolant up to near the top. If this is done the excess coolant will be ejected onto the road until the coolant finds its own level. But some owners get into the habit of continually topping the tank up to the top. You might have seen it when it had been recently filled, before it had ejected the excess.
BUT. It is NOT normal for the level to drop to the point where no coolant is visible in the tank. If you are really sure this is the case I would seek a second opinion ,from a competent garage, ASAP.
Systems should not need to be repeatedly topped up, apart from maybe a tiny amount over a long period. Excessive loss (apart from the initial self levelling mentioned above) suggests a leak.
That said I am not an expert. I am aware that Honda cooling systems operate slightly differently to that found in most cars. My comments are based on some knowledge of 'most cars' but I think its also valid for the Honda system.
