non-replaceable valve inner tubes

dabber

I'm currently having a problem (when out on the road) when pumping up after a puncture with my Lenzyne Pressure Drive pump. On several occasions when having reached a reasonable pressure I've started to unscrew the flexible hose and the inner core valve of the inner tube has come unscrewed with the hose.

The inner tubes are all Continental. I've checked all of the valves to make sure they are tightly screwed in.

Basically, one of the reasons I like the Lenzyne pump because of the ability to use a hose and thereby eliminating the risk of bending the top of the valve.

I realise I could switch to another pump but an alternative would be to change to an inner tube that has fixed valves that don't unscrew. Any suggestions/recommendations please.

maddog 2

Michelin?

or just loctite your current valves in place...?

sungod

as you've found, the valve cores aren't fully tightened when new, but it sounds like either you aren't tightening them enough or you are screwing the pump head on too tight

you need to *really* tighten the core before fitting - you can get a plastic core tool, lbs may just give you one, or splurge on a metal one, or just use pliers

the pump head needs only to be tight enough to seal, which isn't very tight, if you find it isn't sealing it could be the o-ring in the head is worn/damaged/dirty

fwiw i tighten the cores, i use a screw-on lezyne pump, the cores don't come out

dabber

maddog 2 wrote:

Michelin?

or just loctite your current valves in place...?

Thanks... I've just looked at some of the adverts for Michelin Airstops and they seem to have a non-threaded valve stem. So, with those the Lenzyne hose wouldn't be able to screw on. Not sure if the core is removeable or not with these. That's part of the problem. Most of the adverts for all inner tubes aren't very specific on this.

The Loctite idea... that sound like a posssible plan. I've got a few Continentals left so I don't want to dump them.

Anonymous

Loctite low strength threadlock and a little prfe tape will hold them in place, just a little tighten with pliers or such.

dabber

I hadn't thought about using ptfe tape. I'd only need that if there was seepage where the inner core screws into the valve stem wouldn't I? I was under the impression that Loctite threadlock only worked with metal surfaces?

sungod

Dabber wrote:

I hadn't thought about using ptfe tape. I'd only need that if there was seepage where the inner core screws into the valve stem wouldn't I? I was under the impression that Loctite threadlock only worked with metal surfaces?

the surfaces *are* metal, you can use threadlock, or even superglue, to stop the cores coming out

but if you simply tighten the cores fully and don't overtighten the pump head you should be fine

dabber

sungod wrote:

Dabber wrote:

I hadn't thought about using ptfe tape. I'd only need that if there was seepage where the inner core screws into the valve stem wouldn't I? I was under the impression that Loctite threadlock only worked with metal surfaces?

the surfaces *are* metal, you can use threadlock, or even superglue, to stop the cores coming out

but if you simply tighten the cores fully and don't overtighten the pump head you should be fine

Thanks, but.... I know the core/stem surfaces are metal. I was querying whether threadlock would work if ptfe tape was used. I agree about not overtightening the pump hose thread but it's a fairly fine balance between not overtightening and getting a good seal between hose and valve. I'm fed up of trying to sort this when cold and p*ssed off by the side of the raod sorting out a puncture.