Hi all, Would appreciate some advice with my second attempt at fettling a Tilley. This is a late porkpie 246 with the later hood. It has the Hendon pump with the very narrow collar- apart from this it seems same as later pumps. When pressurised the handle comes back under pressure on it own then leaks a lot of paraffin. So the pump non-return valve doesn't seem to be working . I checked the valve and spring. The washer was perished. Changed that, checked spring...all fine. Despite this under pressure the lamp is still pushing back the handle and leaking through the central screw down cap. Any ideas please? Regards, Siatbury
in the words of Columbo..just one more thing. Should the narrow collar that holds the pump in the tank unscrew, like the pump on later models, or does the washer come off down the length of the pump if you see what I mean? Excuse the beginner's terminology
It sounds like your NRV pip is worn out. You can try doing what David suggested. The stretching of the spring allows more pressure to be applied to the pip which pushes the pip against the pump with greater force hence, hoping for a seal. When I haven't got a replacement pip handy, one solution I have found that works quite well is: Remove the pip, find a washer of suitable size, place it where the pip sits then put the pip back. Placing a washer under the pip lifts the pip to protrude slightly above the pip holder and you then get a decent seal.
A rare fault to look for when you have made sure the NRV seems OK is a split pump tube. As I said rare but I have seen two down the years. Easy to check. Remove NRV and holding a finger over the valve end dunk the tube in water leaving the top just clear and pump. A split will show air leaking out. ::Neil::
Thanks all. I've tried new pips, stretching the spring, changing the end for one from another Hendon pump. It is still acting like a syringe and pushing up the handle pumping a load of fuel out. Will try the leak test tonight!
Ok, make sure everything is clean; very clean; and your pip is the correct size. After that: change the spring. If you can blow through the NRV either the spring or the pip is rooted. Cheers Tony
So couldn't resist a bit more fettling before starting work ...glad to say the pump had no cracks after water test. So next tried adapting a biro spring, cutting it down until at the optimum length. Eureka- full pressure and no leaks. I would never have believed the spring could be so critical but I guess if they've never been changed and are 65 years old. anyway thanks for all the advice; much appreciated
Other rare causes of apparent NRV failure I've found over the years - dodgy soldering at the bottom of the pump-tube and in lanterns where the NRV screws out e.g. Bialaddin and Vapaulux, a dodgy external NRV washer, or muck / parts of the old washer left in situ...
My very, very limited experience of pressure lamps is that most of them (Hipolito/Petromax apart!) are simple but capricious little things. The combination of burner, vapouriser and mantle is more like alchemy - one little thing wrong and there's no gold. Of course if they weren't a challenge we wouldn't constatntly need the help of longtime sufferers! Have a good day/evening to you all Si
