frame pump problem

[John Forrest Tomlinson]

I've got a Topeak frame pump and have a problem with it. It's hard to
pull the handle back - seems to be some sort of suction between the
plunger and the head of the pump. Any thoughts on how to fix this?

 

[ScreamRealLoud]

On Jan 4, 5:21 am, John Forrest Tomlinson <[email protected]>
wrote:
> I've got a Topeak frame pump and have a problem with it.  It's hard to
> pull the handle back - seems to be some sort of suction between the
> plunger and the head of the pump.  Any thoughts on how to fix this?

If you can unscrew one end you should be able to simply pull it apart.
Some of the pumps are repairable though, so, be forwarned. If you can
tear your pump apart I'd apply just a very light coating of a thick
lube (I've used Phil's for this stuff). I'd avoid grease since its too
thick, but a chain lube of the thicker variety should be alright.

 

[bfd]

On Jan 4, 8:21 am, ScreamRealLoud <[email protected]> wrote:
> On Jan 4, 5:21 am, John Forrest Tomlinson <[email protected]>
> wrote:
>
> > I've got a Topeak frame pump and have a problem with it.  It's hard to
> > pull the handle back - seems to be some sort of suction between the
> > plunger and the head of the pump.  Any thoughts on how to fix this?
>
> If you can unscrew one end you should be able to simply pull it apart.
> Some of the pumps are repairable though, so, be forwarned. If you can
> tear your pump apart I'd apply just a very light coating of a thick
> lube (I've used Phil's for this stuff). I'd avoid grease since its too
> thick, but a chain lube of the thicker variety should be alright.

This is correct. I have the Topeak Master Blaster full frame pump. An
excellent pump. If you need small parts, Topeak has GREAT service and
is excellent about providing small parts.. Go to their website, they
have an 800 number and call them. They will send you new replacement
parts. Good Luck!

 

[Pat]

"John Forrest Tomlinson" <[email protected]> wrote in message
news:[email protected]...
> I've got a Topeak frame pump and have a problem with it. It's hard to
> pull the handle back - seems to be some sort of suction between the
> plunger and the head of the pump. Any thoughts on how to fix this?

It sounds to me as if the nozzle part is blocked. Have you thought about
that? Look and see if the pump is trying to pull air in but the intake part
is gunked up or the tubing is creased.

 

[John Forrest Tomlinson]

On Fri, 4 Jan 2008 09:45:40 -0800 (PST), bfd <[email protected]> wrote:

>On Jan 4, 8:21 am, ScreamRealLoud <[email protected]> wrote:
>> On Jan 4, 5:21 am, John Forrest Tomlinson <[email protected]>
>> wrote:
>>
>> > I've got a Topeak frame pump and have a problem with it.  It's hard to
>> > pull the handle back - seems to be some sort of suction between the
>> > plunger and the head of the pump.  Any thoughts on how to fix this?
>>
>> If you can unscrew one end you should be able to simply pull it apart.
>> Some of the pumps are repairable though, so, be forwarned. If you can
>> tear your pump apart I'd apply just a very light coating of a thick
>> lube (I've used Phil's for this stuff). I'd avoid grease since its too
>> thick, but a chain lube of the thicker variety should be alright.
>
>This is correct. I have the Topeak Master Blaster full frame pump. An
>excellent pump. If you need small parts, Topeak has GREAT service and
>is excellent about providing small parts.. Go to their website, they
>have an 800 number and call them. They will send you new replacement
>parts. Good Luck!

But I don't know what part is broken, if any. I can unscrew the pump
head, and when do that the the shaft moves freely.

When I put the head back in the suction problem returns. Air makes it
out of the pump when I pump it one way, but there is suction when I
pull the other way.

 

[John Forrest Tomlinson]

On Fri, 4 Jan 2008 15:03:34 -0600, "Pat" <[email protected]>
wrote:

>
>"John Forrest Tomlinson" <[email protected]> wrote in message
>news:[email protected]...
>> I've got a Topeak frame pump and have a problem with it. It's hard to
>> pull the handle back - seems to be some sort of suction between the
>> plunger and the head of the pump. Any thoughts on how to fix this?
>
>It sounds to me as if the nozzle part is blocked. Have you thought about
>that? Look and see if the pump is trying to pull air in but the intake part
>is gunked up or the tubing is creased.
>

It makes sense that air is not getting in, but I don't know what to
check for blockage.

Where is the intake part? Air comes out of the pump when I pump it.

The tubing is smooth.

 

[[email protected]]

On Fri, 04 Jan 2008 18:19:03 -0500, John Forrest Tomlinson
<[email protected]> wrote:

>On Fri, 4 Jan 2008 15:03:34 -0600, "Pat" <[email protected]>
>wrote:
>
>>
>>"John Forrest Tomlinson" <[email protected]> wrote in message
>>news:[email protected]...
>>> I've got a Topeak frame pump and have a problem with it. It's hard to
>>> pull the handle back - seems to be some sort of suction between the
>>> plunger and the head of the pump. Any thoughts on how to fix this?
>>
>>It sounds to me as if the nozzle part is blocked. Have you thought about
>>that? Look and see if the pump is trying to pull air in but the intake part
>>is gunked up or the tubing is creased.
>>
>
>It makes sense that air is not getting in, but I don't know what to
>check for blockage.
>
>Where is the intake part? Air comes out of the pump when I pump it.
>
>The tubing is smooth.

Dear John,

On a typical pump, the air enters the barrel at the top of the
housing, either through tiny inlet holes or just through the clearance
between the top of the housing and the pump shaft.

Once inside the housing, the air goes past the cup-shaped valve on the
bottom of the pump shaft as it's drawn upward. The cup-shape seals on
the down-stroke.

So either you have plugged inlet holes at the top and no air can get
into the barrel . . .

Or you have no inlet holes and just a pump shaft covered with grease
that's clogging the clearance at the top of the pump and no air can
get into the barrel . . .

Or something like grease is still sealing the cup when you pull up and
air in the barrel can't get past the cup . . .

Or you've got a pump that was re-assembled with the cup pointing the
wrong way, which won't let much air in, but can push a little air out
(not much comes out, but enough to fool you).

| a-------------------
|====X========( |/ ============***
| a-------------------

X = where shaft enters barrel, clearance around shaft for air inlet
a = separate air inlet holes on many pumps
( = cup at bottom of shaft, must let air past one way
|/ = one-way flap valve, lets higher-pressure air exit to tire

Cheers,

Carl Fogel

 

[IK]

[email protected] wrote in
news:[email protected]:

> Dear John,
>
> On a typical pump, the air enters the barrel at the top of the
> housing, either through tiny inlet holes or just through the clearance
> between the top of the housing and the pump shaft.
>
> Once inside the housing, the air goes past the cup-shaped valve on the
> bottom of the pump shaft as it's drawn upward. The cup-shape seals on
> the down-stroke.
>
> So either you have plugged inlet holes at the top and no air can get
> into the barrel . . .
>
> Or you have no inlet holes and just a pump shaft covered with grease
> that's clogging the clearance at the top of the pump and no air can
> get into the barrel . . .
>
> Or something like grease is still sealing the cup when you pull up and
> air in the barrel can't get past the cup . . .
>
> Or you've got a pump that was re-assembled with the cup pointing the
> wrong way, which won't let much air in, but can push a little air out
> (not much comes out, but enough to fool you).
>
> | a-------------------
> |====X========( |/ ============***
> | a-------------------
>
> X = where shaft enters barrel, clearance around shaft for air inlet
> a = separate air inlet holes on many pumps
> ( = cup at bottom of shaft, must let air past one way
> |/ = one-way flap valve, lets higher-pressure air exit to tire
>
> Cheers,
>
> Carl Fogel
>

Dear Carl,

Excellent review!

The only possibility you missed was the flap valve is malfunctioning and
it thus not "flapping" at all - it stays open both during down- and
upstroke.

John may want to look into this.

Later,

 

[[email protected]]

On Sat, 05 Jan 2008 04:30:29 GMT, IK <[email protected]> wrote:

>[email protected] wrote in
>news:[email protected]:
>
>> Dear John,
>>
>> On a typical pump, the air enters the barrel at the top of the
>> housing, either through tiny inlet holes or just through the clearance
>> between the top of the housing and the pump shaft.
>>
>> Once inside the housing, the air goes past the cup-shaped valve on the
>> bottom of the pump shaft as it's drawn upward. The cup-shape seals on
>> the down-stroke.
>>
>> So either you have plugged inlet holes at the top and no air can get
>> into the barrel . . .
>>
>> Or you have no inlet holes and just a pump shaft covered with grease
>> that's clogging the clearance at the top of the pump and no air can
>> get into the barrel . . .
>>
>> Or something like grease is still sealing the cup when you pull up and
>> air in the barrel can't get past the cup . . .
>>
>> Or you've got a pump that was re-assembled with the cup pointing the
>> wrong way, which won't let much air in, but can push a little air out
>> (not much comes out, but enough to fool you).
>>
>> | a-------------------
>> |====X========( |/ ============***
>> | a-------------------
>>
>> X = where shaft enters barrel, clearance around shaft for air inlet
>> a = separate air inlet holes on many pumps
>> ( = cup at bottom of shaft, must let air past one way
>> |/ = one-way flap valve, lets higher-pressure air exit to tire
>>
>> Cheers,
>>
>> Carl Fogel
>>
>
>Dear Carl,
>
>Excellent review!
>
>The only possibility you missed was the flap valve is malfunctioning and
>it thus not "flapping" at all - it stays open both during down- and
>upstroke.
>
>John may want to look into this.
>
>Later,

Dear IK,

A stuck valve at the base of the pump shouldn't cause the "suction"
that John describes when he tries to pull the pump handle up.

That valve is normally shut and has nothing to do with letting fresh
air into the barrel.

If the valve is stuck open, the air pumped into the tire will just
blow back out and push the pump handle up.

Either way, there would be no reluctance for the pump handle to come
up. The base valve just can't make the upstroke harder.

If the pump handle refuses to come up easily, then either air isn't
getting into the top of the barrel (plugged inlet) or else the air
can't get past the cup (a cup installed upside down, a cup swollen out
of shape, or lots of grease, oil, or crud).

Given that the pump handle refuses to pull up, but kinda-sorta works
the other way, putting out air, my guess is that the inlet on the top
of the housing is plugged.

Cheers,

Carl Fogel

 

[John Forrest Tomlinson]

On Fri, 04 Jan 2008 18:35:55 -0700, [email protected] wrote:


>On a typical pump, the air enters the barrel at the top of the
>housing, either through tiny inlet holes or just through the clearance
>between the top of the housing and the pump shaft.
>
>Once inside the housing, the air goes past the cup-shaped valve on the
>bottom of the pump shaft as it's drawn upward. The cup-shape seals on
>the down-stroke.
>
>So either you have plugged inlet holes at the top and no air can get
>into the barrel . . .
>
>Or you have no inlet holes and just a pump shaft covered with grease
>that's clogging the clearance at the top of the pump and no air can
>get into the barrel . . .
>
>Or something like grease is still sealing the cup when you pull up and
>air in the barrel can't get past the cup . . .
>
>Or you've got a pump that was re-assembled with the cup pointing the
>wrong way, which won't let much air in, but can push a little air out
>(not much comes out, but enough to fool you).
>
> | a-------------------
> |====X========( |/ ============***
> | a-------------------
>
> X = where shaft enters barrel, clearance around shaft for air inlet
> a = separate air inlet holes on many pumps
> ( = cup at bottom of shaft, must let air past one way
> |/ = one-way flap valve, lets higher-pressure air exit to tire

Thanks

 

[John Forrest Tomlinson]

On Sat, 05 Jan 2008 04:30:29 GMT, IK <[email protected]> wrote:


>
>The only possibility you missed was the flap valve is malfunctioning and
>it thus not "flapping" at all - it stays open both during down- and
>upstroke.
>
>John may want to look into this.
>

Where is the flap valve?

 

[Ryan Cousineau]

In article <[email protected]>,
John Forrest Tomlinson <[email protected]> wrote:

> On Fri, 4 Jan 2008 09:45:40 -0800 (PST), bfd <[email protected]> wrote:
>
> >On Jan 4, 8:21 am, ScreamRealLoud <[email protected]> wrote:
> >> On Jan 4, 5:21 am, John Forrest Tomlinson <[email protected]>
> >> wrote:
> >>
> >> > I've got a Topeak frame pump and have a problem with it.  It's hard to
> >> > pull the handle back - seems to be some sort of suction between the
> >> > plunger and the head of the pump.  Any thoughts on how to fix this?
> >>
> >> If you can unscrew one end you should be able to simply pull it apart.
> >> Some of the pumps are repairable though, so, be forwarned. If you can
> >> tear your pump apart I'd apply just a very light coating of a thick
> >> lube (I've used Phil's for this stuff). I'd avoid grease since its too
> >> thick, but a chain lube of the thicker variety should be alright.
> >
> >This is correct. I have the Topeak Master Blaster full frame pump. An
> >excellent pump. If you need small parts, Topeak has GREAT service and
> >is excellent about providing small parts.. Go to their website, they
> >have an 800 number and call them. They will send you new replacement
> >parts. Good Luck!
>
> But I don't know what part is broken, if any. I can unscrew the pump
> head, and when do that the the shaft moves freely.

Could be the cup seal or the pump head, then. Can't be just the air
intake, because if that was the only thing causing problems, there would
still be a pressure area behind the cup seal when you tried to draw the
pump back.

> When I put the head back in the suction problem returns. Air makes it
> out of the pump when I pump it one way, but there is suction when I
> pull the other way.

--
Ryan Cousineau [email protected] http://www.wiredcola.com/
"My scenarios may give the impression I could be an excellent crook.
Not true - I am a talented lawyer." - Sandy in rec.bicycles.racing

 

[[email protected]]

On Sat, 05 Jan 2008 06:38:17 -0500, John Forrest Tomlinson
<[email protected]> wrote:

>On Sat, 05 Jan 2008 04:30:29 GMT, IK <[email protected]> wrote:
>
>
>>
>>The only possibility you missed was the flap valve is malfunctioning and
>>it thus not "flapping" at all - it stays open both during down- and
>>upstroke.
>>
>>John may want to look into this.
>>
>
>Where is the flap valve?

Dear John,

It's the valve in the base of the pump that prevents the high-pressure
air in the tire from simply blowing right back out of the tire.

If you're having trouble pulling the pump handle up, then that valve
is not your problem.

When the base valve is closed and working properly, the pump handle
pulls up normally--fresh air gets into the barrel from the top, not
the bottom.

If the base valve is stuck open, the pump handle still rises
normally--that side of things has nothing to do with getting fresh air
into the pump barrel.

Cheers,

Carl Fogel

 

[Ben C]

On 2008-01-05, [email protected] <[email protected]> wrote:
> On Sat, 05 Jan 2008 06:38:17 -0500, John Forrest Tomlinson
><[email protected]> wrote:
>
>>On Sat, 05 Jan 2008 04:30:29 GMT, IK <[email protected]> wrote:
>>
>>
>>>
>>>The only possibility you missed was the flap valve is malfunctioning and
>>>it thus not "flapping" at all - it stays open both during down- and
>>>upstroke.
>>>
>>>John may want to look into this.
>>>
>>
>>Where is the flap valve?
>
> Dear John,
>
> It's the valve in the base of the pump that prevents the high-pressure
> air in the tire from simply blowing right back out of the tire.
>
> If you're having trouble pulling the pump handle up, then that valve
> is not your problem.
>
> When the base valve is closed and working properly, the pump handle
> pulls up normally--fresh air gets into the barrel from the top, not
> the bottom.
>
> If the base valve is stuck open, the pump handle still rises
> normally--that side of things has nothing to do with getting fresh air
> into the pump barrel.

If the base valve is stuck open the symptom is presumably that the pump
handle shoots back out again after you push it in. I have had pumps that
did that sometimes. But shouldn't the tyre's valve stop that happening?

 

[[email protected]]

On Sat, 05 Jan 2008 17:13:38 -0600, Ben C <[email protected]> wrote:

>On 2008-01-05, [email protected] <[email protected]> wrote:
>> On Sat, 05 Jan 2008 06:38:17 -0500, John Forrest Tomlinson
>><[email protected]> wrote:
>>
>>>On Sat, 05 Jan 2008 04:30:29 GMT, IK <[email protected]> wrote:
>>>
>>>
>>>>
>>>>The only possibility you missed was the flap valve is malfunctioning and
>>>>it thus not "flapping" at all - it stays open both during down- and
>>>>upstroke.
>>>>
>>>>John may want to look into this.
>>>>
>>>
>>>Where is the flap valve?
>>
>> Dear John,
>>
>> It's the valve in the base of the pump that prevents the high-pressure
>> air in the tire from simply blowing right back out of the tire.
>>
>> If you're having trouble pulling the pump handle up, then that valve
>> is not your problem.
>>
>> When the base valve is closed and working properly, the pump handle
>> pulls up normally--fresh air gets into the barrel from the top, not
>> the bottom.
>>
>> If the base valve is stuck open, the pump handle still rises
>> normally--that side of things has nothing to do with getting fresh air
>> into the pump barrel.
>
>If the base valve is stuck open the symptom is presumably that the pump
>handle shoots back out again after you push it in. I have had pumps that
>did that sometimes. But shouldn't the tyre's valve stop that happening?

Dear Ben,

With a leaky, slightly stuck-open tire valve, you can get very low
back pressure from an inflated tire that's not quite enough to shut
the base valve.

When that happens, the pump handle rises eerily as air from the tire
slowly leaks back out into the pump barrel. I get that sometimes with
my floor pump and Presta valves slightly sticky from Slime.

The Presta valve's tiny nut can also drag against the inside some pump
heads and stay open.

But again, the typical simple pump is just a pair of one-way valves.

Air enters the barrle through the top. As the handle is pulled upward,
the air easily passes the one-way valve of the cup and is trapped on
the other side.

When you push down, the descending cup traps and compresses the air
until the pressure on the pump side of the one-way base valve is
greater than the pressure at the pump head--whoosh, a little air is
forced into the tire.

When you yank the pump head off the tire valve, you usually hear a
whoosh as the air trapped in the tube between the pump head and the
base valve escapes--it's at the same pressure as the tire, but
couldn't escape back into the barrel because the base valve is one
way.

Slightly more complicated pumps inflate on both the push and pull
strokes, a matter of arranging a few more valves and inlets.

Cheers,

Carl Fogel

 

[Ben C]

On 2008-01-05, [email protected] <[email protected]> wrote:
> On Sat, 05 Jan 2008 17:13:38 -0600, Ben C <[email protected]> wrote:
[...]
>>If the base valve is stuck open the symptom is presumably that the pump
>>handle shoots back out again after you push it in. I have had pumps that
>>did that sometimes. But shouldn't the tyre's valve stop that happening?
>
> Dear Ben,
>
> With a leaky, slightly stuck-open tire valve, you can get very low
> back pressure from an inflated tire that's not quite enough to shut
> the base valve.

I think the tyre on which I experienced that may have had a Schrader
valve. The pump handle didn't creep but pinged back with quite a bit of
force.

I think it is possible to inflate a tyre with a Schrader valve using
pressure in the pump alone to overcome the spring holding the valve
shut. But some pumps push a little plunger in against the valve's
spring-loaded pin, relying on the seal between the grommet in the pump
head and the valve stem to keep the air in. This possibly makes
inflation easier since you don't have to push against the spring on each
stroke to open the valve.

If the pin is held pushed in then the valve stays open and the air will
rush out of the tyre into the pump, forcing the handle back up if the
valve has failed. I think that may have been what was happening.

[...]
> The Presta valve's tiny nut can also drag against the inside some pump
> heads and stay open.
>
> But again, the typical simple pump is just a pair of one-way valves.
>
> Air enters the barrle through the top. As the handle is pulled upward,
> the air easily passes the one-way valve of the cup and is trapped on
> the other side.
>
> When you push down, the descending cup traps and compresses the air
> until the pressure on the pump side of the one-way base valve is
> greater than the pressure at the pump head--whoosh, a little air is
> forced into the tire.

It is only a little air, but it is all the air you sucked in on that
stroke. It doesn't go anywhere else.

> When you yank the pump head off the tire valve, you usually hear a
> whoosh as the air trapped in the tube between the pump head and the
> base valve escapes--it's at the same pressure as the tire, but
> couldn't escape back into the barrel because the base valve is one
> way.

Yes, I get that (on my decent pump that works

Removing a pump head from a Shrader valve on the other hand I think can
let out some of the air you just put into the tyre if the seal between
the grommet and valve stem is broken before the plunger has disengaged
the valve poppet.

 

[[email protected]]

On Sun, 06 Jan 2008 15:58:16 -0600, Ben C <[email protected]> wrote:

>On 2008-01-05, [email protected] <[email protected]> wrote:
>> On Sat, 05 Jan 2008 17:13:38 -0600, Ben C <[email protected]> wrote:

>> When you push down, the descending cup traps and compresses the air
>> until the pressure on the pump side of the one-way base valve is
>> greater than the pressure at the pump head--whoosh, a little air is
>> forced into the tire.
>
>It is only a little air, but it is all the air you sucked in on that
>stroke. It doesn't go anywhere else.

Dear Ben,

Technically, all the air that enters the barrel does not wind up in
the tire.

On the first stroke, a surprising amount of the compressed air is left
in the hose leading to the tire at the same pressure as the air in the
tire.

The more you pump, the more compressed air is trapped in the hose
leading to the tire. Depending on the tube length, its inside
diameter, and the size of the barrel, it can end up being as much as a
full pump.

That's the whoosh that you hear when you pull the pump head off the
tire valve--a tube full of 110 psi air escaping.

My favorite story about such easily overlooked details is about the
NASCAR racer who noticed that the rules carefully limited the size of
the gas tank, but neglected to specify the diameter of the fuel line
from gas tank to carburetor.

So he replaced his standard fuel line with something as thick as a
garden hose, correctly calculating that twelve feet of one-inch
diameter fuel line would hold enough extra gas (effectively enlarging
his fuel tank roughly 100 cubic inches) to let him skip one pit stop
in a long race.

Sadly, NASCAR caught onto his trick right away and added a rule about
fuel line diameter.

Cheers,

Carl Fogel