THE INTERNATIONAL JAGUAR 'S'-TYPE REGISTER FORUM

Recently my scuttle flap was rising and then slowly falling and I knew I had a leak on the vacuum side that operated it. Today I pulled the three button switch out of the dash and set up my vacuum pump to test all the switches. Both the scuttle flap and the heater valve worked fine once I had created a vacuum in their lines.
Next I disconnected the vacuum line from the C19425 Vacuum tank heater under the left wheel arch and set up a vacuum on the line and again both valves were working so the leak was either the vacuum tank or the hose coming from the brake vacuum tank.
I removed the heater vacuum tank from under the left wheel arch and tried to create a vacuum in the tank and it did not hold. OK so I connected a hose to the inlet, dunked the tank in a bucket of water and blew and lots of bubbles came out from just under where the bracket is welded to the side of the tank. OK can't cost a lot for a new one so checked SNG and David Manners and I have found another part that is no longer being made!!!!!!

Do not have a spare in my many boxes of spares.

Checked on EBay where I have seen loads of secondhand ones for sale in the past and not one today.

Looks like I am going to have to repair this one!

Rob

If originality is not a concern you could fit a brake vacuum tank C24910 that is available.

Norman

I've seen a number of those severely corroded due to location under the wheel arch.

All sorted now. The metal is too thin to weld but it all cleaned up well and allowed me to patch up the hole with araldite. As it is a vacuum and not a pressure tank it is trying to pull the araldite into the hole rather than pushing it out so it has sealed very nicely. Followed up with another coat of black paint and some underseal and hopefully it should outlast me.

I suspect mine is about to go the same way as yours, Rob. The flap closes slowly a while after turning the engine off. I've been trying to ignore it. .

I'll bear in mind your fix when the time comes.

You obviously have a leak but it is finding where the leak is first. Could be one of the hoses that has become old and perished. Mine were all in good condition. Could be the return valve on the tank that is allowing the vacuum to leak back out or it could be a hole in the tank as I had. There is no shield on this tank like the one on the brake vacuum tank so it might get pitted by rust and stones. My leak was under the fixing bracket where some mud had been caught in the past and had rusted through the side of the tank.
I have a brake vacuum bleeder which I was able to attach to the various tubes to create a vacuum so I could test them all.

I sand blasted mine until spotless & then self etch primed followed by many protective coats.

Thanks for the tips, chaps. Several things to look at there. I will get around to it at some point.

I had a bit of a look at this today. There's nothing obviously awry, so I have ordered up one of those vacuum testers and will chase the problem through until I find it.

One quick question, Rob: How does one detach the non-return valve from the tank?

The pipe is a push in fit to the vacuum cylinder from what I remember so a pair of plumbers pliers or monkey wrench should do it but I also seem to think that the top section is screwed in to the pipe. As long as you try and unscrew it you will either loosen the pipe or unscrew the top whichever gives way first.
There is one for sale on EBay with pictures at https://www.ebay.co.uk/itm/JAGUAR-DAIML ... XQQANREpLS to give you an idea and the photo is reproduced below. The part number C27005 is being sold on SNG but has a slightly different design in that the tubes are opposite each other rather than sticking out the same side. The picture of theirs is also below and this is why I think the top section is a screw fit. I do not think I have a spare but will go and take a look.