Series 3 heater control valve leak

Morning

My S3 (88 2.25 petrol) overheated very rapidly recently, normally runs fine in centre of temp gauge when warmed up. Coolant sprayed all round engine bay (see gif). Assume diaphragm in heater control valve has failed, or am I barking up the wrong tree? Grateful for any ideas, thanks.

Yes, and I don't think there a lot you con do other then get a new one.

I removed mine completely and replaced it with a simple brass elbow connector and hose tail. That means that water is flowing into the heater matrix permanently.

Being a Series, I don't even notice that heater is "on" when the fan is switched off.

I decided that this was a safer option than replacing with a cheap modern production valve.

My S2A has the manual tap type but when it leaked I replaced with a much older version that was repairable as the modern ones are sealed and when they leak they are junk.

I hope it's ok to resurrect an old thread.....

I have a leaking valve on a 2.25 diesel and like the idea above of a simple elbow. I presume it is a bsp thread that is required but can anyone tell me what size thread and hise barb are needed please? I know I can measure it but would like to have one ready to fit when I take the leaky valve off ideally!

It depends. I seem to recall the valve is screwed into a fitting that is screwed into the head. I think there are different threads each end. I'm pretty sure one is BSP but the other one is not.

Series 2 parts book lists the rear connection for heater hose as 3/8BSF not sure if that carried over to later engines.
Front connection is 3/8bsp