Pump problem

In article <[email hidden]>

POHB said:

Had my first puncture for many months yesterday. Found and fixed it
pretty quick, but pumping up the tyre the mini pump started "slipping".
That is to say if I pumped too fast it would go part way in and then
there would be no resistance. I remember now it had started to do this
when I was fixing loads of punctures last year before I got some
tougher tyres.
Is this likely to be something I can fix? Can I grease or replace a
washer somewhere? It is a Specialized airforce 2. Should I just buy a
new one to avoid risking it giving up on me at an inconvenient moment?

You could try greasing it, but it sounds like the barrel is worn out.
Don't use any petroleum-based grease as it may vapourize in the pump and
rot your innertubes. You can get silicone grease from places that sell
RC cars, airguns or diving gear. Or eBay, of course.

in message <[email hidden]>, POHB

(') said:

Had my first puncture for many months yesterday. Found and fixed it
pretty quick, but pumping up the tyre the mini pump started "slipping".
That is to say if I pumped too fast it would go part way in and then
there would be no resistance. I remember now it had started to do this
when I was fixing loads of punctures last year before I got some
tougher tyres.
Is this likely to be something I can fix? Can I grease or replace a
washer somewhere? It is a Specialized airforce 2. Should I just buy a
new one to avoid risking it giving up on me at an inconvenient moment?

Blackburn sell repair kits for their pumps, and full kits of spare
parts - which is one of my main reasons for buying and recommending
them. It's possible that Specialised do too, although I don't know this.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

;; in faecibus sapiens rheum propagabit

Rob Morley said:

In article <[email hidden]>

POHB said:

Had my first puncture for many months yesterday. Found and fixed it
pretty quick, but pumping up the tyre the mini pump started "slipping".
That is to say if I pumped too fast it would go part way in and then
there would be no resistance. I remember now it had started to do this
when I was fixing loads of punctures last year before I got some
tougher tyres.
Is this likely to be something I can fix? Can I grease or replace a
washer somewhere? It is a Specialized airforce 2. Should I just buy a
new one to avoid risking it giving up on me at an inconvenient moment?

You could try greasing it, but it sounds like the barrel is worn out.
Don't use any petroleum-based grease as it may vapourize in the pump and
rot your innertubes. You can get silicone grease from places that sell
RC cars, airguns or diving gear. Or eBay, of course.

Well worth having a look inside before deciding it's toast. If the
washer looks obviously dry and hardened greasing will probably fix it,
or failing that, a new washer.

I wasn't aware of the petroleum-based grease issue. Sounds like good
advice.

--
Dave...

Simon Brooke said:

in message <[email hidden]>, POHB

(') said:

Had my first puncture for many months yesterday. Found and fixed it
pretty quick, but pumping up the tyre the mini pump started "slipping".
That is to say if I pumped too fast it would go part way in and then
there would be no resistance. I remember now it had started to do this
when I was fixing loads of punctures last year before I got some
tougher tyres.
Is this likely to be something I can fix? Can I grease or replace a
washer somewhere? It is a Specialized airforce 2. Should I just buy a
new one to avoid risking it giving up on me at an inconvenient moment?

Blackburn sell repair kits for their pumps, and full kits of spare
parts - which is one of my main reasons for buying and recommending
them. It's possible that Specialised do too, although I don't know this.

My Blackburn did this a repair kit cured it, somewhere in the pump
there must be a one way valve, in the Blackburn this is a small
circular disc, mine had split.

I concur with Simon the availability of the repair kit was the reason
I purchased the Blackburn, Repair kit is around £4.00, contains two
full sets of all seals and washers, even contains the little part that
pushes the core in on a Schrader (car) type valve

Steve

Rob Morley <[email hidden]>typed

Quoted message said:

You could try greasing it, but it sounds like the barrel is worn out.

Err... how can a barrel 'wear out'?

Quoted message said:

Don't use any petroleum-based grease as it may vapourize in the pump and
rot your innertubes. You can get silicone grease from places that sell
RC cars, airguns or diving gear. Or eBay, of course.

Saliva is a good emergency lubricant ;-)

--
Helen D. Vecht: [email hidden]
Edgware.

In article <[email hidden]>

Helen Deborah Vecht said:

Rob Morley <[email hidden]>typed

Quoted message said:

You could try greasing it, but it sounds like the barrel is worn out.

Err... how can a barrel 'wear out'?

At the business end of the barrel the seal is pressed harder against the
wall by the increased pressure of air, wiping away grease that has
reduced viscosity because of the high temperature created by
compression. If there is any abrasive contaminant in the barrel this
can be trapped between the seal and the barrel, causing striations which
reduce the effectiveness of the seal.

Rob Morley said:

Quoted message said:

Quoted message said:

You could try greasing it, but it sounds like the barrel is worn out.

Err... how can a barrel 'wear out'?

At the business end of the barrel the seal is pressed harder against the
wall by the increased pressure of air, wiping away grease that has
reduced viscosity because of the high temperature created by
compression. If there is any abrasive contaminant in the barrel this
can be trapped between the seal and the barrel, causing striations which
reduce the effectiveness of the seal.

I've not gotten around to taking it apart yet, but I doubt that's the
problem.
When the pump "slips" it goes suddenly, going from lots of resistance
to none.
If I pump more slowly it doesn't slip, at least not so often.
Feels like a seal is being pushed open the wrong way or something.
I'll have to perform a disection.

POHB said:

Should I just buy a
new one to avoid risking it giving up on me at an inconvenient moment?

Well that settles it. I was just trying it out again with a view to
greasing and it fell apart in my hands. The shaft had obviously got
metal fatigue. Don't know if that was the cause of the original
problem but I'll have to buy a new one now.