Switched the heater to hot today and the heater valve started leaking (onto the exhaust producing a lot of steam!). If I switch back to cold the leaking stops. The water is coming from the valve housing. I guess it’s faulty but it looks very new. Anyone know law have a leaking valve?

 

The tap needs replacing, it's that simple, and there are no serviceable parts inside.
When open, coolant flows past the rubber diaphragm inside, and that' where the leak is.
When it's closed, the area that leaks is shut off from the coolant flow.

 

This is a link to the SNG valve. https://www.sngbarratt.com/English/#/UK/parts/dc33089f-a24b-437a-a136-a89961370b9b?fromList=Search%20for%20%60heater%20c ontrol%20valve%60

 

Thanks. I think it was restored and then never used.

 

I understand the replacement valves can be a little stiff. It's a good idea to work it back and forth a few times to make sure it's free before installation.

 

This valve is vacuum-controlled, while Rishi’s valve seem to be wire-controlled. Requires some remodeling. Maybe this will fit right on? (for Mk1 and Mk2)

https://www.sngbarratt.com/English/#...%20%60c9927%60

 

https://www.sngbarratt.com/English/#...y=HEATING(4526)

I think this is the correct one for a mk2

 

Sorry Martin, I missed your post. At least, we both linked to the same component.

 

😊

 

Peter
You are correct for the mechanically/cable-controlled heater valves for MK1 and MK2 cars.
I understand the S types used the vacuum driven system.

 

Yes my mistake. I was when I started the post thinking that Rishi had an S Type as he was originally looking at one. I then changed the written post to reflect the Mk2 heater valve but missed changing the link to the correct one from SNG. Sorry for the confusion.

 

No problem. I have ordered the correct part from SNG.

I will loose some coolant whilst replacing the valve. Is it correct to use G12+?

 

If you don't care about staying OE, there are plastic ones that cost little. There are also solenoid operated if you want to give up on adjusting the cable.

Anti-freeze: make sure you top up with the same colour. It's important not to mix different types. If Glyn is around, he will explain or Google one of his previous explanations.

 

Just fitted the new valve and O ring. The valve was very stiff but it is working. I don't have the full movement of the slider in the cabin but the valve does open and close fully. All went well until the final tightening of the two bolts attaching the valve to the heater box. I was being very careful but not careful enough and I stripped the thread on the bottom bolt. It's not leaking but I don't want to take a chance so I think I will tap it out to 5mm and put an M5 bolt in. Any other suggestions?