MSR Trailshot Woes - fixed?

Talk about anything.

Moderators: Bearbonesnorm, Taylor, Chew

Post Reply
User avatar
whitestone
Posts: 7847
Joined: Thu Dec 04, 2014 10:20 am
Location: Skipton(ish)
Contact:

MSR Trailshot Woes - fixed?

Post by whitestone »

I've had a Trailshot for some time but I've never really had good throughput. Cath got herself one last year and the difference between the two was night and day - whereas the claimed 1 litre per minute throughput was probably achievable with hers, mine was more like 100ml per min.

Summat's up :sad:

Now there's not many bits to the Trailshot, eleven to be precise, so there's not much to go wrong. So this is a sort of a work through in locating the problem.

Was it the filter cartridge? Well I hoped not since that would be almost the price of a whole new Trailshot. A full clean, several times, and things were a little better. I also did MSR's integrity test (Google this, it's an easy test to perform) and everything seemed OK.

Going through how the Trailshot works and also having a known working unit to compare to, I noticed that the priming of the unit was different. You squeeze the bulb about ten times to fill its reservoir - at this point you should get full flow. My unit would only fill to about 20% so when I subsequently squeezed the bulb to get water rather than force the incompressible water through the cartridge I was compressing air hence sod all flow.

No water was escaping from the bulb so it wasn't damaged. I checked the pre-filter and check-valve (a sort of one-way valve) and everything was clear so water could get in. Taking the cap assembly off I happened to try squeezing the bulb and it began filling, a few more squeezes and it filled completely! So the cap was somehow preventing the bulb from working properly, curious. I tried various levels of tightening the cap down with occasionally explosively wet results :lol: I also swapped parts back and forth between the working unit and mine but with no real difference in its behaviour.

All this while my attention had been on the bulb, after all that's where "the problem" lay. Then during one attempt at priming I happened to notice air bubbles escaping from between the male and female parts of the check valve housing. Try the working unit - no bubbles. Hmm. Now I'm beginning to better understand how all the parts work together ...

At either end of the system is a one way valve, the check valve at the input and the umbrella valve in the output cap, both are aligned so that flow occurs from the dirty to the clean side. During priming when you squeeze the bulb air is expelled through the umbrella valve, when you release the bulb the partial vacuum seals the umbrella valve whilst at the same time allowing water to enter via the check valve. Repeat until bulb is full at which point you get full output flow.

In my case the leak at the input end meant that I wasn't creating enough pressure to create the partial vacuum so a check and clean of the housings and a tighten with pliers and I'm now able to fill the bulb and get good flow. It must just be a case of manufacturing tolerances but I think a washer at that point would make sense rather than rely on two pieces of fairly hard plastic to accurately mate and make a seal.

Edit:

I went back and tried to prime a second time and no luck :sad: A bit of searching about Trailshot priming problems and it seems the above paragraph isn't quite right in that priming doesn't rely on the check valve to work. One suggestion was to remove the input filter and check valve altogether to prime the unit. This works! In fact it only takes three squeezes of the bulb to fully prime it but you do need the input above the output, i.e point the unit down by about 45deg. Taking the end of the tube out of the water to replace the input filter only introduces a little air back into the system. Two potential problems:

1. You might drop the input filter and/or the check valve :shock:
2. The initial priming could be using cloudy water with particulates so will clog the filter quicker.

Not an ideal solution but it does mean my unit will work. I thought it might have been my check valve but swapping it for the other one and there's still no improvement so it's possible that there's multiple faults with mine all combining to prevent correct priming.
Last edited by whitestone on Fri Sep 06, 2019 5:04 pm, edited 2 times in total.
Better weight than wisdom, a traveller cannot carry
User avatar
sean_iow
Posts: 4269
Joined: Tue Sep 30, 2014 12:08 pm
Location: Isle of Wight

Re: MSR Trailshot Woes - fixed?

Post by sean_iow »

This could explain why some users (myself) think the Trailshot is much faster than a sawyer (which I also have) and others think the sawyer is better. Without two Trailshots side by side to compare you wouldn't know if there was an issue or if that was just how they work.
Adventure without risk is Disneyland - Bikemonger
User avatar
PaulB2
Posts: 1952
Joined: Fri Mar 10, 2017 8:32 pm
Location: Stafford

Re: MSR Trailshot Woes - fixed?

Post by PaulB2 »

That might explain the issues with my trailshot. I'll have to take it apart and have a look.
User avatar
whitestone
Posts: 7847
Joined: Thu Dec 04, 2014 10:20 am
Location: Skipton(ish)
Contact:

Re: MSR Trailshot Woes - fixed?

Post by whitestone »

One other thing I came across was an update from an MSR rep about the cleaning regimen.
It's unfortunate that whoever sent you this filter failed to make it very clear that every time you use this filter it should be shaken, very vigorously, for a minimum of 30 seconds. If you do this, you will not see much diminishing of flow rate. All filters will slow down over time. If not I'd be worried. Their job is to take out stuff from water including microbes so small as to require a 0.2 micron absolute filter size (this is extremely and mind-boggingly small). Cleaning these filters by shaking is extremely effective, again, especially if you do it every time you filter. To do so, simply remove the hose (it pops off easily), cover both the outlet and inlet holes with your finger and thumb, and then VIGOROUSLY shake (put your back into it!). Once you're done shaking, simply give the TrailShot a squeeze which will squirt out the bad water (it's surprising how dirty this water is, even when filtering seemingly clean water). I'd also recommend draining the rest of the water out of the hose by turning it upside down (the prefilter has a one-way valve that doesn't allow the water to exit). Finally replace the hose, fold it up against the body of the filter, replace the rubber band, and store.
Doesn't help that the manual still says 20 seconds shaking every eight litres!
Better weight than wisdom, a traveller cannot carry
User avatar
sean_iow
Posts: 4269
Joined: Tue Sep 30, 2014 12:08 pm
Location: Isle of Wight

Re: MSR Trailshot Woes - fixed?

Post by sean_iow »

I shake mine every use and then pull the hose off to empty, it keeps the filter clean and the emptying reduces the weight :wink:
Adventure without risk is Disneyland - Bikemonger
slarge
Posts: 2641
Joined: Mon Aug 22, 2011 4:49 pm
Location: MTB mecca (Warwickshire)

Re: MSR Trailshot Woes - fixed?

Post by slarge »

There's a much easier fix Bob

Simply write in permanent marker "Cath" on the faulty one, and "Bob" on the working one, and you'll have a filter that works really well. :-bd
RobLyon
Posts: 134
Joined: Thu Jun 16, 2016 5:43 pm
Location: East Yorkshire

Re: MSR Trailshot Woes - fixed?

Post by RobLyon »

I've noticed with mine it doesn't like the filter clamp nut done too tight. If I back it off a little it works fine but back it off to far and the filter pops out. So slightly loose with a gentle squeeze to pump works best.
lune ranger
Posts: 2380
Joined: Thu Dec 15, 2016 7:52 pm
Location: Peoples Republic of Devon

Re: MSR Trailshot Woes - fixed?

Post by lune ranger »

Sold mine as I never really got on with it.
Flow was never that good and I found the squeeze pumping action quite hard work when doing long ITTs
I replaced mine with a Sawyer Micro squeeze which is great. Very easy to filter with as long as there is a decent amount of water to fill the bag from. Did the Braunton 150 with it in hot weather at mid summer. I only used a single 700ml bottle so had to refill many times and was never a bother even when I was hanging after 24hrs.
If you are going through hell, keep going.
WSC
Post Reply