did the radiator. No better.

I drained the coolant and flushed the rad and block (AFTER I managed to get the rubber hoses off the metal bits).

I couldn't get the putty far enough into the fins, and there are 2 holes in it. Rad change this weekend then.

BUT..... Monday it ran fine, and lost water as normal (50 miles).
Tuesday morning all fine.
Tuesday afternoon on the way home the coolant light was flashing. The expansion tank was at the max line, the temp gauge was normal, as was the oil temp gauge.

I had a look this afternoon before I started it up (it flashes 5 seconds after start up, so the engine is stone cold....).

The temp sensor in the block (near the oil filler cap) has a plug under it. I hadn't tightened the hose which was just above it, so the rubber plug shroud was full of water. I tightened the jubilee clip, and slid the rubber shroud down, hopefully that is causing a short (as it is even when cold), and it will dry out.

what about using red well?

or is this similar to what Simmo suggests?

I have been advised against Rad Weld unless I am selling the car as it gums up the engine.

Simmo suggested the metal putty which is what I tried, but I couldn't push it in far enough because of the fins.

I have 1 spare rad sitting about, and 2 others on my spare cars, so I will change the rad, but save the (BLOODY EXPENSIVE!!) coolant mixture and put it back in.

I will also get new jubilee clips, as the old ones were rusty and were hard to put back on.

Cheers

Steve