Mk1 Cabby 1.5 engine water leak - help wanted

I've just got a Mk1 Golf 1.5 Cab running that's been out of action since Christmas - needed to replace the old Pierburg carb with a Weber 36TLP (now done ok).

When I filled the radiator before starting the car, I spotted the water running straight out (engine not running so no pressure in system).  I put car up onto ramps and could see water running down from behind the sump central, in the starter motor area. With the engine running the water pumps more quickly.

All the hoses that I could see from the front / underside looked and felt ok. and I can't see anything obvious from above.

Previously (before the carb work was done) the car used to use up a little water - not excessive but advisable to keep a can of water in the car 'just in case'. Needed topping up every couple of weeks or so.

The engine sounds fine - doesn't sound as if anything has blown.

Can anyone suggest what/where the problem might be? Thanks.

check your core plugs havent popped or rusted away if your car didnt have anti freeze the core plug may of popped out or just rotted away.
i have a sweet running 1.5 engine handy as a spare.

Did you look with tourch etc?
I would suggest using one and closely inspecting every single pipe you see slowly.
Some pipes have never been removed in the car's lifetime , problem is limescale builds on the pipes, all this needs to be cleaned, water flsuhed in and out fo every pipe to clean system.
It could be a coreplug, what i did not like was you stating you've been topping up the water before, this would suggesst "maybe" head or core plug".
Again this can be caused as mentioned using no anti freeze etc a some just think all the need to do is turn the key lol.
The car should not be using any water atall.
On this one comes down to common sense bud, nothing much advice i think can give you apart for just looking about.

OK, thanks guys, I'll do a closer check 'cos I'd hate to fail after the work we've put in lately and she's ticking over so sweetly now (briefly with water coming out!).

IF it's core plugs, is this terminal, or can they be replaced?

They can be replaced fella.
If block is pressuizing, the very last thing to go is core plug.

You're a star Pete.  Just ordered four plugs.

Fun this!  8O