I used to think that the S Type's vacuum operated system was a negative. On reflection, as long as you have a good water valve, it seems a positive. Mine works like a charm. The only negative is you are using hot air to demist which is slow. Modern vehicles use AC cold air to demist which happens very quickly.

 

My heater flap is not spring loaded. It must be set and held in the desired position.

 

Yes. I think Peter was suggesting a spring might help in that case. I'm an S Type man and don't know all the differences to the Mk2. I use Lin's blog for Mk2 queries.

 

https://valvechatter.com/?p=2116

 

A very useful resource for Mk2 owners.

 

Thanks, I have been looking for something like this!
Fantastic content from Lin. I hope he leaves it up.

 

He intends leaving it active.

 

Lin's valvechatter is classic. Landieman is also very helpful:

https://landieman.com/

For the spring, I think, but I'm not certain, there should be one present, but it's not very strong and rusts away. Generally, apart from not having the capacity to deliver large volumes of very hot air, the heater works so long as it's regularly used with a warmed up engine. A period without use, especially in a humid environment, and the flap seals stick or fall off, the hinges rust solid, and the whole device deteriorates.

 

Just get used to using the site. Some have difficulty.
https://valvechatter.com/?p=2116
Jag Mk2
Go to " Restoration Blog"
> Then to all the drop down menues
> Then where applicable sub drop down menues

Good luck!

 

Improved/consolidated to 1 post.