Post by aggsandrog on Jan 30, 2009 16:50:32 GMT
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I gather these commonly fail, so I took mine apart to investigate. The main cap and the retaining ring are hard plastic. The main cap houses the lock, which simple expels a polythene peg about 7x 4 mm when unlocked. The peg engages in one of a set of channels moulded on the inside of the centre wheel. This is always meshed with the outer castellated ring which has 3 pegs on it to engage with the filler neck. These last 2 items are polythene. There is a spring between the lock moulding and the centre wheel to create a tight fit with the filler neck. When the cap is locked, the polythene peg is withdrawn into the main cap moulding. The drive to the centre wheel is removed, so the main cap then turns without turning the outer castellated ring with the 3 pegs and the cap will not come off.
Still there? I'll be asking questions later!
The problem with mine is that the outer castellated ring has hardened with age, and is too tight a fit to turn inside the main cap moulding. The cap therefore came off even when locked. The only cure in my view is to lubricate the mating surfaces of the outer castellated ring and the main cap moulding. To do this, remove the black rubber seal, compress the spring (in a clamp or vice) and introduce a lubricant into the now visible castellations.
I did damage mine taking it apart, but I managed to rebuild it using super glue to refix the retaining ring. I think the problem with the caps is made worse by have a spring which is too powerful, so I permanently compressed mine a bit.
As a matter of interest any ticking you hear is the polythene peg jumping slots and is not relevant to the cause of the problem.
I read somewhere that good motorhome spares stores carry a large supply of these caps. I am not surprised. If lubrication as I suggest does not work for you, the only answer is replacement.
I gather these commonly fail, so I took mine apart to investigate. The main cap and the retaining ring are hard plastic. The main cap houses the lock, which simple expels a polythene peg about 7x 4 mm when unlocked. The peg engages in one of a set of channels moulded on the inside of the centre wheel. This is always meshed with the outer castellated ring which has 3 pegs on it to engage with the filler neck. These last 2 items are polythene. There is a spring between the lock moulding and the centre wheel to create a tight fit with the filler neck. When the cap is locked, the polythene peg is withdrawn into the main cap moulding. The drive to the centre wheel is removed, so the main cap then turns without turning the outer castellated ring with the 3 pegs and the cap will not come off.Still there? I'll be asking questions later!
The problem with mine is that the outer castellated ring has hardened with age, and is too tight a fit to turn inside the main cap moulding. The cap therefore came off even when locked. The only cure in my view is to lubricate the mating surfaces of the outer castellated ring and the main cap moulding. To do this, remove the black rubber seal, compress the spring (in a clamp or vice) and introduce a lubricant into the now visible castellations.
I did damage mine taking it apart, but I managed to rebuild it using super glue to refix the retaining ring. I think the problem with the caps is made worse by have a spring which is too powerful, so I permanently compressed mine a bit.
As a matter of interest any ticking you hear is the polythene peg jumping slots and is not relevant to the cause of the problem.
I read somewhere that good motorhome spares stores carry a large supply of these caps. I am not surprised. If lubrication as I suggest does not work for you, the only answer is replacement.
