Seized water filler cap

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twinkeel

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Water filler cap has seized and refuses to respond to usual key

Applied WD40 - no change

Bought larger key - no go

Applied mole wrench to new key - bent key

Drilled two holes in cap, inserted two machine screws and applied wrench to those - I cannot budge it but the metal is somewhat soft and the SS machine screws bent the cap

I think that I will end up having to drill / cut it out in pieces

Meanwhile - any bright ideas ?
 
It sounds like a nightmare. It might be worth using freeing oil, such as Plus Gas, which is much more effective than WD40. Heat would probably be too hazardous.
 
Is it the common alloy one with a screwdriver type slot?

When we bought our boat we had the same problem. I used some penetrating oil, and then used a blunt cold chisel and hammer at the end of the slot to tap it round. It took some walloping and has left a dent at the edge of the slot, but it came free in the end. Since then have made sure that I apply a little smear of silicone grease to the mating surfaces regularly.
 
i would agree with using a cold chisel and hammer i had the same problem and it worked you need a shock loading to release the grip of the corrosion
 
they do a tin of lubricating freezer spray for removing seized stuff. The thermal shock causes tiny movement and thus allows the lubricant into the threads. I've found it to work but it's about 12 quid a tin so try the hot water first. Sorry can't remember where I bought it - halfords or a chandlery probably.
 
Yes its the light grey alloy

Am concerned about hitting it too hard as risk moving the socket which is screw to the deck.

Will try the boiling water trick - once the weather improves

Thanks for the input
 
twinkeel said:
Water filler cap has seized and refuses to respond to usual key

Applied WD40 - no change

Bought larger key - no go

Applied mole wrench to new key - bent key

Drilled two holes in cap, inserted two machine screws and applied wrench to those - I cannot budge it but the metal is somewhat soft and the SS machine screws bent the cap

I think that I will end up having to drill / cut it out in pieces

Meanwhile - any bright ideas ?
Click to expand...

May seem like an odd question, but is the boat ashore or afloat ? I once had a water filler cap that would open perfectly freely when the boat was afloat but was impossible when ashore. I assume that there were slight distortions in the deck when the weight was not supported by water.
 
Can you not remove it, if alol this advice fails? (The chisel approach does work well, used it myself on an alloy filler this autumn)
If you can get it out you can heat it and 'stuff'!
Good luck.....
 
We had this with the alloy cap on our Snappie. I thumped away with a chisel and bloody great hammer to no available. Spoke to engineer in the boatyard who came with a small chisel and a little peen hammer and he tapped away and then it moved. It was obviously the vibration that did it not the brute force.
 
Freed mine with the kettle of hot water. Salt, or salt formed aluminium chloride, dissolved in the warm water. Silicone grease keeps it right.

Had the same problem with the diesel filler and with some care to avoid water entering the fuel tank, freed ot off with a kettle also.
 
If the filler is aluminium try aluminium wheel cleaner. Use sume putty to make a dam around the filler then fill with wheel cleaner and leave over night.
 
The method i used when this happened was to buy or find an old spade drill bit, grind off the point and shape so it fitted the slot. stick it in a hammer drill with torque setting and put it in reverse.
then poured boiling water over it for a minute (2 jugs).


then drill away so to speak, the vibration broke it freee within 20 seconds or so but it was noisey.

Steve
 
Lots of ingenuity in the replies so many thanks to all

Off to demolish some Christmas cake now but will give it a fresh go in the New Year
 
savageseadog said:
To sort this problem out I removed it from the deck. Use a blowlamp or a pan of boiling oil.
Click to expand...

Yes, not a lot of seized components will resist a blowlamp. Hope so anyway, as my windlass is completely seized and must come apart. Blowlamp was the advice of the agent. Unlike a water filler, which should come off the boat easily, my windlass has to be freed in-situ so is a rather bigger problem.
 
Definitely try the blunt chisel and hammer method - get it on the perimeter and try in two opposite positions alternating the blows, half a dozen blows then try at the opposite side. I've used this method several times and it usually works. Nick the perimeter first with a sharp chisel and then use a blunt chisel.
 
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