GlennR

So i've been having a problem with my 5 year old Bontrager track pump. I have 2 bikes, one with tubes and one tubeless.

Last year I found the head was popping off the stem and it seemed like the sealant was acting as a lubricant causing the head to pop off the smooth stem when I pumped up my 25mm tires to 90psi. I replaced the "gasket" and it worked for a few months and started to happen again. I contracted Bontrager (Trek) and they sent me a new head of a different design (separate presta and schrader openings). This worked all year but today I had a different problem. When I pumped up the tubeless (32mm) the handle of the pump with, by itself, would extend all the way up. Like the air I just pushed in was coming back out. I decided to replace the presta core but that didn't help. I then tried the pump on a wheel with a tube and same problem.

I guess there is a one way valve, in the head, which prevents the air you just pushed in from just coming out and it's stuck open from the sealant.

I sprayed some Simple Green into the head and let it sit for a bit. Then used the pump to blow it out. I then tried the pump and it "seems" OK for now.

So....

Is the sealant getting blown into the pump head and gumming it up? And if so how do I prevent it or do I need to periodically need to clean the head?

I can't be the only one that experienced this.

WhyFi

I haven't experienced this. I don't understand how you are getting this much sealant past the stem valve and in to the pump head.

Do you use a *lot* of sealant and pump up with the stem at the 6-o'clock position?

GlennR

The bike is stored hanging from a hook.

I usually have the stem at 12:00 when i pump. I haven't added any sealant in 10 months.

DaveSSS 

Only pump with the valve around 6 o'clock. I never use a pump head that pushes down and breaks the presta seal. Tap the lock
nut to let a little air out, then use a head like a hirame or push on silca.

WhyFi

Dunno, then - I'm at a loss. If you're not submersing the valve stem in the sealant, the stem valve should be keeping the sealant spray in check (a little misty blow-out is normal in my experience, but that's *after* removing the head), so I'm not sure how you're accomplishing this.

What kind of shape was the valve in when you removed it?

FWIW, I also have a Bontrager floor pump and have been using it with tubeless tires for 5+ years.

JohnJ80

Lennard Zinn to the rescue - store your bike with the valve stem down. That way any sealant drains out. You're not going to get a lot of sealant in the valve by rolling the tire around since the centrifugal force wants to pull it out of the stem. The problem, at least how I see it, is that if you don't store your tires with the stem down, then some of the sealant can start to congeal if there is a slow leak. When that happens, it creates the potential to trap more sealant in the stem and makes it easier to get in the pump. This has really worked well for me. I used to have problems like this all the time but not any more.

The other issue, of which I am guilty, is that I tend to be pretty aggressive at adding sealant. If you get too much in the tire, it gets really easy for it to pool in the bottom and for it to get into the stem. Too little is no good and so is too much.

I typically pump mine up with the stem at 12 like you do and I don't have a problem. I have Silca pumps and they don't open the presta valve until I start pumping unless I push them on too far. But, if that happens - and it does on occasionally (generally a long time between) - then I just clean out the pump head. Fortunately, on Silca pumps, that's pretty easy. I have had problems with other pumps where if I got sealant in them, the head was essentially damaged.

FWIW, if you haven't added sealant in 10 months, it's probably pretty thick already. Being think means it won't run out of the stem either once you get some in there. You might want to take the tire off and take a look, clean it up and put in fresh sealant.

bruce19

I have the same pump about the same age. I hang my bikes like you do. I've never had anything like the issue you cite. Also at a total loss to explain.

jaxgtr

I had this issue sort of, but I started ensuring my valves are at 6 o clock when I put the bike in my bike racks and it has not been an issue since.

JohnJ80

Yes. This eliminated probably 90+% of the issues I had with tubeless and the issues of sealant leakage when inflating and valves clogging.

GlennR

I can say that after I unscrew the locking tip I do make sure the pin is free by pressing on it before I put the pump head on. There are times that the locking tip needs more grip to unscrew.

When I removed the original core, it looked fine but when ahead and replaced it anyway.

Maybe I just need to clean the head once every few months. It could be it's getting a bit of blowback which is causing to to stick.

I might contract Bontrager and see if they're send me a replacement head.

JohnJ80

Ive been riding tubeless now on all bikes since about 2009. Before tubeless clinchers were out, I was riding Tufo Tubulars which are tubeless. All the same problems etc... with sealant were there too. It's no different than road tubeless today.

So, with that in mind, the three things I do with tubeless are:

1. keep a supply of presta cores around. A presta core, in my experience, gets plugged up with the sealant working it's way up alongside of the shaft inside the main tube. It's almost impossible to dig the hardened latex out of there, and for what a valve costs, easy to replace.
2. It is ssential to have a pump head that is easy to disassemble and clean. It's bad if the design of the head is such that you have to replace the entire head, and I wouldn't recommend a pump where you had to do that. I finally gave a high end Lezyne pump to a friend that didn't have tubeless wheels for that reason alone.
3. Store your bike with the valves between 4 and 8 but preferably at 6 o'clock. This has done more for me than anything else. Doing this, I rarely have problems with #1 or #2.

All that aside, the hassle factor with tubeless has been easily an order of magnitude less for me than with tubed tires. I'd never go back .

jaxgtr

I also found that some sealants are worse about clogging the cores than others, so I would assume that some of that could carry into the pump head if you were pumping from 12 o clock. I found the Bontrager sealant would clog my cores up really fast no matter where I positioned my valves. I tried Orange Seal and it has been much more friendly with my valve cores.

rsbob 

Had the same issue with a sprayer tank, the handle would pop up and pressure. I took it apart and found there is a rubber seal/valve that was not correctly seating in the plunger due to a piece of who knows what - in your case probably a lump of sealant. See if you can completely disassemble the pump and fine that seal/valve. I bet that is your issue.

canklecat

Last time my pump chuck clogged with sealant I used an ammonia cleaner followed by plain water. Worked fine. Most liquid "rubber" or latex products use ammonia type solvents/carriers to stay in suspension. Ditto India ink and calligraphy inks, so ammonia will clean up those old nibs and clogged fountain pens.

WhyFi

Will ammonia clean up $$$ bibs that have been sprayed with sealant? Asking for a friend.

Racing Dan

The handle popping up is a sign the check valve, in the pump, is not closing reliably. The CV is not in the head. Its somewhere between the piston and the manometer. Often there is a ball in the pump head as well. Its there to "auto detect" if you use the the presta or schrader outlet. If the ball is stuck you may experience air rushing out the wrong outlet and no pressure in the one you need.

Some pumps does not have a check valve. If that is the case and the handle pops put from back pressure, its a sign the valve in the wheel is not closing between each pump stroke. Sometimes an issue if the wheel valve sticks with sealant or is just defective and you are using an ordinary frame pump.

eduskator

I'd say that these also better clog punctures, which is a good thing!

OP: As we all know, tubeless setups generally requires more TLC than tubes. I've had a few clogged valve cores in the past that resulted in slow leaks and in sealant entering inside my pump's head (my pump pushes the stem down when I connect it), and I have learned from it. I store the bike with the valves @ 6 o'clock and inflate tires at this position (more or less) as well. I check the valve cores every once in a while to make sure that there's no dried sealant close to the seal. If so, it's a sign that the pump needs to be inspected/cleaned. You may need to do this more often, only time will tell. To me, I does not seem like your pump is faulty.

canklecat

Ammonia type cleaners are less effective on latex or rubber that's cured or become clumpy like boogers. Same with masking fluid used by watercolor painters -- once that latex masking fluid is no longer fluid, ammonia won't restore it to a thick fluid that can be brushed on with some accuracy.

I've used very dilute ammonia type cleanser sprays to clean up my old school steel road bike's white rubber hoods. Works great, but leaves the hoods feeling a bit soft and tacky. I suspect that with repeated use it would eventually degrade the hoods. I use it maybe once or twice a year and wipe with plain water after cleanup.