Msr Dragonfly

[matt2matt2002]

Hi folks
I am the proud owner of a second hand Dragonfly - via ebay
When giving it a check over (empty of fuel) I noticed an air leak from the brass vlave.
I have the old type pump.
I can see the leak when I pump it up and put the top part under water.
It is from where the brass plunger goes into the brass nut. Not from where the brass nut sits against the plastic blue part of the pump head.
Does that make sense?
Is it the black gromits leaking?
Or should I put pdf tape around the brass thread?

Thanks folks

[psmiffy]

pdf tape?

If you mean PTFE tape - and if i am wrong I hope someone will correct me - the fuel will dissolve it

[rualexander]

If I understand your description properly, I think you need to replace the relevant rubber 'o' ring in the valve assembly.
Replacing the 'o'rings on these pumps is an easy job so probably worth replacing them all at the same time anyway if you are buying the service kit.

[matt2matt2002]

pdf tape?

If you mean PTFE tape - and if i am wrong I hope someone will correct me - the fuel will dissolve it

Thanks - yes I did mean PTFE tape - sorry.
A pal had suggested that - but I suspect you are correct and it will dissolve. Thanks for the advice.

[matt2matt2002]

If I understand your description properly, I think you need to replace the relevant rubber 'o' ring in the valve assembly.
Replacing the 'o'rings on these pumps is an easy job so probably worth replacing them all at the same time anyway if you are buying the service kit.

This is what I had thought I should do - so thanks for confirming my thoughts.

I have looked at MSR kits for annual maintenance but spending over £15 for all the bits seems a shame when all I need are the 'o' rings.
Any idea where I can pick up a couple? They appear to be 2 different sizes btw.

[al_yrpal]

O rings? Our old fashioned dustcoated ironmonger. Seek out one near you.

Al

[rualexander]

Looks like the o rings can be found separately : http://www.needlesports.com/Catalogue/C ... MSR-DFFAOR
If that is the right one.
Best to get the correct type rather than just any o ring as they have to be compatible with the fuel you are going to use.

[Gearoidmuar]

Photographs of problem...

[BeeKeeper]

There are some pictures of a dragonfly being dismantled here: http://www.bushcraftuk.com/forum/showthread.php?t=43601 I don't think this is the same model as you have but it might be of some use.

It would also be worth cleaning the O ring and the shaft which goes through it and then lubricating it with something like Vaseline. This might be all that is necessary - unless the O ring is actually damaged or badly worn, in which case it will need replacing. Any O ring from a local shop will be fine with the fuel.

[matt2matt2002]

Photographs of problem...

Camera out of action for a while but will try later

[matt2matt2002]

There are some pictures of a dragonfly being dismantled here: http://www.bushcraftuk.com/forum/showthread.php?t=43601 I don't think this is the same model as you have but it might be of some use.

It would also be worth cleaning the O ring and the shaft which goes through it and then lubricating it with something like Vaseline. This might be all that is necessary - unless the O ring is actually damaged or badly worn, in which case it will need replacing. Any O ring from a local shop will be fine with the fuel.

Not quite the same model - but very interesting to read. Thanks

[matt2matt2002]

pdf tape?

If you mean PTFE tape - and if i am wrong I hope someone will correct me - the fuel will dissolve it

Thanks - yes I did mean PTFE tape - sorry.
A pal had suggested that - but I suspect you are correct and it will dissolve. Thanks for the advice.

A pal gave me some PTFE tape this afternoon and said he has used it with aviation fuel!
But I appreciate your own comments.

I have ordered some new 'o' rings but had a bash with the tape and it did stop the leak.
I think it is a bad design having a brass thread going into a plastic part.
Any comments on that, folks?

As I tighten the thread I am unsure when to stop. And on previous inspections I have seen fine threads of plastic come out as I removed the brass part.
(Is this the cause of the problem? And am I up a gumtree now?)

In conclusion - so far - I think the leak is from the thread not the 'o' rings but will replace them anyway.

More thoughts welcome folks.
I want to be sure before I light up!

[rualexander]

You could always try it out with paraffin rather than petrol, that way if there is a leak it won't be so dangerous as paraffin isn't a so volatile and doesn't light easily. Needless to say, do it outdoors though, as paraffin is a bit messy.

[BeeKeeper]

PTFE is more or less inert - it won't be melted by any common fuel. And "aviation fuel" is (without being nitpicking) paraffin or kerosene, depending on which side of the Atlantic you live.

[matt2matt2002]

You could always try it out with paraffin rather than petrol, that way if there is a leak it won't be so dangerous as paraffin isn't a so volatile and doesn't light easily. Needless to say, do it outdoors though, as paraffin is a bit messy.

Good idea. But I can see the leak when I submerge the pumped up bottle in a sink full of cold water.