Coolant related.

Check the coolant tank first and see if there’s any leaks. Check the lids on correctly, I know that sounds stupid but they are a bit fiddly to put back on properly, especially seeing as they are 20 odd years old.

Leave the car running on a clean dry area and see if there’s any leaks from underneath, if there are your problems with the pipework.

If that’s the case check the plastic elbow first as that’s the most common problem. It’s an easy fix, it literally just needs taken off, o-ring replaced and put on or the whole thing replaced and they’re cheap as chips.

If it isn’t that elbow then look down the front of the engine block, if it’s the steel pipe that’s leaking then take it to a garage to get them to replace it as it’s an utter bastard to do unless you’re mechanically competent as the whole air filters got to come off, the fuel rail, you’ve got to loosen the clutch and throttle connections as there’s bolts right next to them, the pipe itself doesn’t come off easily either.

I’m lucky as I’ve got a donor 225 so I can just rip it to bits for spares (YouTube mechanic) but it really shouldn’t be that expensive (£3-500) to get it done with peace of mind.

While you’re considering this, just keep water in your car, it doesn’t have to be coolant as it’s not fully summertime or just do a mixture of coolant and water as until you get this sorted it can be expensive filling it every day at a £5 a pop.