Header tank : Change the steam valve gasket and seal

This maintenance is part of the repainting of the header tank.


Although much more confortable, It is not necessary to remove the header tank to access to the steam valve. It is anyway necessary to empty it.

0-Remove the header tank

Perform the 8 first steps of the process explained here.

1-Remove the 5 cheese head screws securing the steam valve cap

These screws are notoriously fragile and will break easily if stuck or overtorqued. I found them to be a non standard size, so I used plenty of W40 and an adjustable spanner.
Tools: Small adjustable spanner

2-Steam valve cap partially removed

Notice that the two screws securing the warning plate are longer and also have thick washers.

3-Steam valve cap removed

The sealing gasket has to be scrapped.

4-Scrapping the sealing gasket

Takes time if you don't have a special product for doing so

5-Pulling out the steam valve

It just sits into its recess. If stuck, use a pair of pliers and do gently. Notice how it comes because it can easily remounted upside down.

6-Remove the Washer fitted beneath the steam valve and cleaning the surface where the new seal gasket

7-Remove the remaining hoses

The drain pipe is most certainly dry and soldered to its pipe. You'll have to cut it.

8-Obstruct the header tank pipes and fill it with a mixture of 10% citric acid - 90% water

Let it rest one hour or two then clean with mains water. This is done in order to decalcify the inside of the tank. But not mandatory.

9-If needed, repaint the tank using back high temperature gloss paint.

Prior to painting, clean the surface.It is a lot better if with a spray gun
Tools: Spray gun

10-Fit a new inner sealing gasket in the steam valve recess

Spare Parts: Seal for steam valve (UR15870)

11-Fit the steam valve

On this picture, the valve is facing upside down. Also notice that the little hole on the side of the valve has to be facing *in front* of the little hole you can notice in the recess. This part is not known as failing often. A new valve would cost around 100 GBP.
Spare Parts: Steam valve 15psi (UR16730)

12-Fit the steam valve cover gasket

Spare Parts: Steam valve cover gasket (RH12745)

13-Put the cover and screws back in place

Note the long screws and thick washers go for retaining the warning plate. Beware of making the text face the rear of the engine, or just the drain pipe that you see in the rear (just not like on this picture!)

14-Torque the cheesehead nuts moderately

Avoid using too long a wrench. If possible use antiseize coating on the threads.
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