THE INTERNATIONAL JAGUAR 'S'-TYPE REGISTER FORUM

Orlando St.R wrote: ↑Tue Aug 13, 2019 9:05 pm 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 was thinking about this Orlando and if the flap is holding open with the engine running but closes when the engine goes off it means the tank is not holding the vacuum. This could mean you have a small hole in the tank, a leak in the rubber tube or the non return valve C27005 is not sealing and allowing the vacuum to be filled or the three button switch is not sealing. My flap closes as soon as I turn off the engine and as my tank is now air tight, I have checked the hoses and the three button switch, I can only think my valve is not working as designed.
In my box of many things I have a spare three button switch with all the hoses still connected.

Thanks for the extra info, Rob, (inc C27005 - as usual not easy to find on SNGB). And thanks for thinking about why mine might not be working properly.

My flap has always slowly closed after 30 mins or so, but now does so within 5 mins. I will wait until the vacuum tester arrives and test the various bits of the system. The tank seems hard enough to remove; the nuts are solid; so I don't want to have to remove it unless I really have to! I will report back once diagnosis is complete.

With yours, I guess the non-return valve is the only item you've not been able to test.

Orlando St.R wrote: ↑Fri Aug 16, 2019 6:15 pm My flap has always slowly closed after 30 mins or so, but now does so within 5 mins.

The tank seems hard enough to remove; the nuts are solid; so I don't want to have to remove it unless I really have to! I will report back once diagnosis is complete.

With yours, I guess the non-return valve is the only item you've not been able to test.

When I switch off my flap closes almost instantly so it has to be the non return valve but a £50 a pop new from SNG I will put up with it closing.


The Tank is held on with two half inch nuts on studs. Even if you snapped the studs it would very easy to either drill out and put a bolt through as you can get to the top or to put a bolt in the hole and weld the head in place to turn it in to a stud.

Not difficult to test the non return valve if you set up the vacuum pump in such away to create a vacuum in the tank via the outlet to the rubber tube to see if it held. I might try this via the back of the three button switch as this is how I checked to see if the tank was holding a vacuum when I found the hole but I did not recheck it when I reassembled it as the flap was now working.