Removable valve core failures
09-20-19 | 08:32 AM
#26
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The reason that chucks have either a different hole or a different configuration is because of the nature of the valve. Yes, the pump has it's own check valve but that check valve allows for a small amount of pressure change in the hose. Since the Schrader valve is held open, that doesn't matter for that valve. But for a Presta valve, the change causes the valve to close. Pressure introduced when the piston in the pump is pushed down causes it to open again. It goes through a cycle of opening and closing.
I'm not saying that the pump doesn't have a check valve. I'm saying that the Presta valve closes at a very low pressure differential. Most all hoses leak some air around the valve stem. This can be because valve stems have threads or because of a poor fit but nearly all of them leak some air. For a Schrader valve, that leak is coming out of the tube. For a Presta, the valve closes until the pressure outside the tire is higher (by a very small amount) than inside.
The chucks have to be different because of the way that the valve has to be used.
I'm not saying that the pump doesn't have a check valve. I'm saying that the Presta valve closes at a very low pressure differential. Most all hoses leak some air around the valve stem. This can be because valve stems have threads or because of a poor fit but nearly all of them leak some air. For a Schrader valve, that leak is coming out of the tube. For a Presta, the valve closes until the pressure outside the tire is higher (by a very small amount) than inside.
The chucks have to be different because of the way that the valve has to be used.
09-20-19 | 08:48 AM
#27
climber has-been
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Here's my personal "do it once and learn your lesson" valve core failure, Presta edition.
While topping off tire pressure in the garage before a ride:
While topping off tire pressure in the garage before a ride:
- Attempt to unscrew the valve nut.
- Unscrew the valve core instead.
- Valve core becomes projectile that ricochets through the garage.
- Try to find where valve core landed, but fail.
- Have no spare valve cores.
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Last edited by terrymorse; 09-20-19 at 09:57 AM. Reason: grammar
09-20-19 | 09:25 AM
#28
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A tube valve is absolutely required to put pressure into the tube. More importantly, it is necessary to keep the pressure in the valve. Prestas have to be forced to open and they close easily. Any "in and out" of the air in the tube is due to the valve not operating properly or because it is damaged. If the core is loose, it could leak around the bottom of the core. If the stem is damaged...pulled out of the tube...it will also leak. Given the description, my money is on the stem being damaged and 44.5mph just didn't notice it.
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Dreamin' of Bemidji Down the Mississippi (in part)
Plan Epsilon Around Lake Michigan in the era of Covid
Gold Fever Three days of dirt in Colorado
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Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Stuart Black
Dreamin' of Bemidji Down the Mississippi (in part)
Plan Epsilon Around Lake Michigan in the era of Covid
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
09-20-19 | 09:49 AM
#29
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It is relevant. 44.5mph already ruled out the pump...
A tube valve is absolutely required to put pressure into the tube. More importantly, it is necessary to keep the pressure in the valve. Prestas have to be forced to open and they close easily. Any "in and out" of the air in the tube is due to the valve not operating properly or because it is damaged. If the core is loose, it could leak around the bottom of the core. If the stem is damaged...pulled out of the tube...it will also leak. Given the description, my money is on the stem being damaged and 44.5mph just didn't notice it.
A tube valve is absolutely required to put pressure into the tube. More importantly, it is necessary to keep the pressure in the valve. Prestas have to be forced to open and they close easily. Any "in and out" of the air in the tube is due to the valve not operating properly or because it is damaged. If the core is loose, it could leak around the bottom of the core. If the stem is damaged...pulled out of the tube...it will also leak. Given the description, my money is on the stem being damaged and 44.5mph just didn't notice it.
Here is a link to a hack/bodge segment of a GCN video I saw yesterday.
Edit: If the video starts from the beginning, go to 24:24 to see what I am talking about.
09-20-19 | 09:58 AM
#30
Senior Member
Joined: Apr 2012
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From: Nor Cal
it is relevant. 44.5mph already ruled out the pump...
a tube valve core is absolutely not required to put pressure into the tube. More importantly, it is necessary to keep the pressure in the valve. Prestas have to be forced to open and they close easily. Any "in and out" of the air in the tube is due to the valve not operating properly or because it is damaged. If the core is loose, it could leak around the bottom of the core. If the stem is damaged...pulled out of the tube...it will also leak. Given the description, my money is on the stem being damaged and 44.5mph just didn't notice it.
a tube valve core is absolutely not required to put pressure into the tube. More importantly, it is necessary to keep the pressure in the valve. Prestas have to be forced to open and they close easily. Any "in and out" of the air in the tube is due to the valve not operating properly or because it is damaged. If the core is loose, it could leak around the bottom of the core. If the stem is damaged...pulled out of the tube...it will also leak. Given the description, my money is on the stem being damaged and 44.5mph just didn't notice it.
09-20-19 | 10:16 AM
#31
Senior Member
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From: Alpharetta, GA
Bikes: Nashbar Road
I still think that OP's problem might be - likely is - the removable valve stem not being tight. I've had the same thing happen, unfortunately recently enough that I should have known better.
It's getting dark, in a hurry to get home, unscrew the valve nut exactly like always and waste a CO2 cartridge in an instant. Likely I unscrewed the valve core when I though it was the nut turning. With a pump, same thing. After I got that situated, air in the tube, I couldn't get the screw-on pump nozzle off without removing the valve core. If I hadn't also had a Presta adapter to just leave on the stem and using the Schrader pump nozzle I'd have been SOL. So I know it can happen that way, and I suspect that's what happened to OP.
Just tightening it down later with pliers wasn't enough BTW.
It's getting dark, in a hurry to get home, unscrew the valve nut exactly like always and waste a CO2 cartridge in an instant. Likely I unscrewed the valve core when I though it was the nut turning. With a pump, same thing. After I got that situated, air in the tube, I couldn't get the screw-on pump nozzle off without removing the valve core. If I hadn't also had a Presta adapter to just leave on the stem and using the Schrader pump nozzle I'd have been SOL. So I know it can happen that way, and I suspect that's what happened to OP.
Just tightening it down later with pliers wasn't enough BTW.
09-20-19 | 10:25 AM
#32
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It's getting dark, in a hurry to get home, unscrew the valve nut exactly like always and waste a CO2 cartridge in an instant. Likely I unscrewed the valve core when I though it was the nut turning. With a pump, same thing. After I got that situated, air in the tube, I couldn't get the screw-on pump nozzle off without removing the valve core.
09-20-19 | 11:53 AM
#33
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From: CA
Either Locktite the core, or remember to let it warm up and thaw before unscrewing the chuck.
09-20-19 | 03:01 PM
#34
Mad bike riding scientist
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From: Denver, CO
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44.5 did try another pump, but this was likely operator error or some other problem. Pumps have check valves so the valve is not necessary to act as a check valve - it might make pumping less efficient for presta valves, but you can still get air in to a tube without the valve functioning... it will all escape as soon as you take the pump off, but it goes in in the first place.
If the valve doesn't open, you can't get air in the tube. Point one for why you need the valve. And if the valve doesn't function properly or is missing, you can't keep air in the tube. The point is to put air in the tube and to keep it there.
Malfunctioning valve that would let the pressure out when the pump was removed, so the pump was left in place for the ride home., essentially relying on the check valve in the pump to put the air in and keep it there.
Edit: If the video starts from the beginning, go to 24:24 to see what I am talking about.
Edit: If the video starts from the beginning, go to 24:24 to see what I am talking about.
It didn't need fixing. See above.
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Stuart Black
Dreamin' of Bemidji Down the Mississippi (in part)
Plan Epsilon Around Lake Michigan in the era of Covid
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Stuart Black
Dreamin' of Bemidji Down the Mississippi (in part)
Plan Epsilon Around Lake Michigan in the era of Covid
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
09-20-19 | 03:26 PM
#35
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How many angels fit on a pin head?
If the valve doesn't open, you can't get air in the tube. Point one for why you need the valve. And if the valve doesn't function properly or is missing, you can't keep air in the tube. The point is to put air in the tube and to keep it there.
That trick will only work if you have the right kind of pump. Most pumps are going to have thumb locks and those won't seal as well.
If the valve doesn't open, you can't get air in the tube. Point one for why you need the valve. And if the valve doesn't function properly or is missing, you can't keep air in the tube. The point is to put air in the tube and to keep it there.
That trick will only work if you have the right kind of pump. Most pumps are going to have thumb locks and those won't seal as well.
As for the video, it is not a recommendation on how to pump properly and skip the pesky step of tightening the nut on the presta valve, but a demonstration that OP's understanding of the pump-tube interface was flawed.
09-20-19 | 04:34 PM
#36
Generally bewildered
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From: Eastern PA, USA
Bikes: 2014 Trek Domane 6.9, 1999 LeMond Zurich, 1978 Schwinn Superior
Also, I've seen (in my cores) where the rubber gasket in the core that seals things actually rolls out of it the groove its supposed to be in. Pretty sure this had to do with sealant, but if not, there's a justification: you can fix the valve by replacing the core without removing the tube and tire.
09-20-19 | 04:50 PM
#37
Mad bike riding scientist
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From: Denver, CO
Bikes: Some silver ones, a red one, a black and orange one, and a few titanium ones
If you re-read the OP's description of the problem, he was not able to get the air in the tube (pump rebounded after pushing air in) and suspected it was because of a faulty removable valve core letting the air back into the pump. My point was not that valves are not necessary on tubes, which is absurd, but that OP's problem was not one of a leaky valve or valve that fails to close, because that's not how pumps work. As I have said many times in this thread, pumps have a check valve, and air will not push back in to a properly functioning pump because the valve on the tube is faulty - there would be other problems caused by a malfunctioning valve, but OP's problem is not one of them.
It has become a rubber lung: pump air in, exhale air out, pump air in, exhale air out while your pump pressure gauge keeps returning to 0.
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Stuart Black
Dreamin' of Bemidji Down the Mississippi (in part)
Plan Epsilon Around Lake Michigan in the era of Covid
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Stuart Black
Dreamin' of Bemidji Down the Mississippi (in part)
Plan Epsilon Around Lake Michigan in the era of Covid
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
09-20-19 | 04:53 PM
#38
Mad bike riding scientist
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From: Denver, CO
Bikes: Some silver ones, a red one, a black and orange one, and a few titanium ones
Maybe for tubes, but for tubeless, it's pretty easy to gunk up a valve core.
Also, I've seen (in my cores) where the rubber gasket in the core that seals things actually rolls out of it the groove its supposed to be in. Pretty sure this had to do with sealant, but if not, there's a justification: you can fix the valve by replacing the core without removing the tube and tire.
Also, I've seen (in my cores) where the rubber gasket in the core that seals things actually rolls out of it the groove its supposed to be in. Pretty sure this had to do with sealant, but if not, there's a justification: you can fix the valve by replacing the core without removing the tube and tire.
__________________
Stuart Black
Dreamin' of Bemidji Down the Mississippi (in part)
Plan Epsilon Around Lake Michigan in the era of Covid
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Stuart Black
Dreamin' of Bemidji Down the Mississippi (in part)
Plan Epsilon Around Lake Michigan in the era of Covid
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
09-20-19 | 05:14 PM
#39
Senior Member
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It is relevant. 44.5mph already ruled out the pump...
A tube valve is absolutely required to put pressure into the tube. More importantly, it is necessary to keep the pressure in the valve. Prestas have to be forced to open and they close easily. Any "in and out" of the air in the tube is due to the valve not operating properly or because it is damaged. If the core is loose, it could leak around the bottom of the core. If the stem is damaged...pulled out of the tube...it will also leak. Given the description, my money is on the stem being damaged and 44.5mph just didn't notice it.
A tube valve is absolutely required to put pressure into the tube. More importantly, it is necessary to keep the pressure in the valve. Prestas have to be forced to open and they close easily. Any "in and out" of the air in the tube is due to the valve not operating properly or because it is damaged. If the core is loose, it could leak around the bottom of the core. If the stem is damaged...pulled out of the tube...it will also leak. Given the description, my money is on the stem being damaged and 44.5mph just didn't notice it.
09-20-19 | 09:15 PM
#40
Generally bewildered
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From: Eastern PA, USA
Bikes: 2014 Trek Domane 6.9, 1999 LeMond Zurich, 1978 Schwinn Superior
What kind of reactors do you deal with?
09-21-19 | 09:09 AM
#41
Mad bike riding scientist
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From: Denver, CO
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I'm a chemical engineer, cycco. Pretty familiar with a lot of different reactors (including nuclear). Interesting: PTFE (of which Teflon(R) is one brand) doesn't do well with gamma radiation. Lots of stories about trace components destroying seals in chemical reactors as well.
What kind of reactors do you deal with?
What kind of reactors do you deal with?
__________________
Stuart Black
Dreamin' of Bemidji Down the Mississippi (in part)
Plan Epsilon Around Lake Michigan in the era of Covid
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Stuart Black
Dreamin' of Bemidji Down the Mississippi (in part)
Plan Epsilon Around Lake Michigan in the era of Covid
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
09-21-19 | 09:18 AM
#42
Mad bike riding scientist
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From: Denver, CO
Bikes: Some silver ones, a red one, a black and orange one, and a few titanium ones
If the floor pump doesnt have a check valve or if the check valve is defective, a Presta valve has a better chance of being able to be pumped up than a Schrader. The Presta will close on the back stroke of the pump and act as a check valve like the pumps own check valve. A Schrader valve will just flow back into the pump and push the handle up. If you can get air back into the shaft...which could be a big if...you could get air into the Presta and make it stay there. The same can be said for the Schrader.
__________________
Stuart Black
Dreamin' of Bemidji Down the Mississippi (in part)
Plan Epsilon Around Lake Michigan in the era of Covid
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Stuart Black
Dreamin' of Bemidji Down the Mississippi (in part)
Plan Epsilon Around Lake Michigan in the era of Covid
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
08-09-21 | 02:05 PM
#43
Thread Starter
Too slow
Joined: Feb 2008
Posts: 109
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From: Russellville, Ar
Just pumped up another tire with a removalbe presta valve. When pressure reached 100psi, all the air came back thru the valve and pressure was lost. Tried using 2 other pumps and got the lung effect. 5 psi, 0, 5 psi , 0.
So then I turned on my air compressor and screwed on a presta to schrader adaptor. The top of the presta stem free floated in the adaptor. Used the chuck to air up the tire. As soon as the chuck was removed, the tire deflated.
Problem = PRESTA VALVE, not the pumps or compressor.
Removed the tight valve using a wrench. Cleaned the inside of the stem with a pipe cleaner & screwed in a new valve stem. Same results. Now this tube had been patched several times and inflated at least weekly over its life.
My opinion: Tubes with removable presta valve cores have a limited life.
Imagine some poor soul with this problem on the road and tries to inflate the tire using $4 Co2 cartridges. Kiss those goodbye.
Anyway, I have a new tube with a smooth OD valve stem to install.
So then I turned on my air compressor and screwed on a presta to schrader adaptor. The top of the presta stem free floated in the adaptor. Used the chuck to air up the tire. As soon as the chuck was removed, the tire deflated.
Problem = PRESTA VALVE, not the pumps or compressor.
Removed the tight valve using a wrench. Cleaned the inside of the stem with a pipe cleaner & screwed in a new valve stem. Same results. Now this tube had been patched several times and inflated at least weekly over its life.
My opinion: Tubes with removable presta valve cores have a limited life.
Imagine some poor soul with this problem on the road and tries to inflate the tire using $4 Co2 cartridges. Kiss those goodbye.
Anyway, I have a new tube with a smooth OD valve stem to install.
08-09-21 | 02:33 PM
#45
Senior Member
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From: San Diego, CA
I have the same routine except my tires get pumped up at least twice a week. My tubes seem to last around several years or more and 10+ patches and it's been a couple decades since I've had a failed removable presta core. I think you have very bad luck or doing something wrong.
08-10-21 | 01:32 AM
#47
Droid on a mission
Joined: May 2018
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From: Palm Coast, FL
Bikes: Diamondback Wildwood Classic
Here's my personal "do it once and learn your lesson" valve core failure, Presta edition.
While topping off tire pressure in the garage before a ride:
While topping off tire pressure in the garage before a ride:
- Attempt to unscrew the valve nut.
- Unscrew the valve core instead.
- Valve core becomes projectile that ricochets through the garage.
- Try to find where valve core landed, but fail.
- Have no spare valve cores.
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