Deflating Tyres with compressor

[Keithyv]

More chance of losing the valve core I suppose if you take it out.
Also a valve body is not really designed for the core to be screwed in and out too many times I suppose.
Plus the more you mess with it the more likely it is to leak.

They are my thoughts..

[Merts]

Most times I use one of the ARB type tyre deflators (mine's from Supacentre) which removes the valve. Many others in our 4WD club use them too. I've never seen or even heard of someone losing a valve (it's not really possible using one of these deflators) or cross threading, or valves starting to leak because they've been removed and replaced.

Sometimes I just use the pin on the back of my digital tyre gauge to depress the valve. Whilst the air doesn't escape as quickly, you save time not having to screw the deflator on, screw the valve out, then back in, then remove the deflator. One of these days I should time the two processes to get an accurate idea of which is quicker and by how much. I have a trip planned in a couple of weeks. I reckon I will do it then.

[Kingbrown]

On a related topic, I remember as a young bloke being castigated by my tyre dealer at the time for having el-cheapo plastic valve caps.

Unlile the metal valve caps, plastic valve caps do not have an integral seal as a backup in case the valve leaks.

Worse still is to have no valve caps at all, especially in typical 4WD environments where mud and dust can clog the valve &/or compromise the sealing of the valve seat.

Finally, take care with the gear that you are using with your valves. Air chucks, airlines and couplings, deflators, gauges etc should be kept free of dust and dirt and stored appropriately.

[old Jack]

On a related topic, I remember as a young bloke being castigated by my tyre dealer at the time for having el-cheapo plastic valve caps.

Unlile the metal valve caps, plastic valve caps do not have an integral seal as a backup in case the valve leaks.

Worse still is to have no valve caps at all, especially in typical 4WD environments where mud and dust can clog the valve &/or compromise the sealing of the valve seat.

Finally, take care with the gear that you are using with your valves. Air chucks, airlines and couplings, deflators, gauges etc should be kept free of dust and dirt and stored appropriately.

Need to be really careful using metal valve caps unless the cap is brass as aluminum or steel caps can easily and quickly corrode on tight an you do not have to do a lot of beach driving for this to happen !

Corrosion is galvanic and caused by dissimilar metals of the valve stem and the cap combined with moisture.

There are 2 sorts of plastic caps, the soft type that do not have and internal seal and these should not be used. The hard plastic valve stem caps that have an internal seal are the best and these are what comes standard with new valve stems which should always be changed when fitting new tyres.


OJ.

[Kingbrown]

Good points there OJ.

I've removed a bit of the silvery coating on one of a handful of identical metal caps and the substrate has a brassy colour. There's nil attraction to a rare earth magnet so they're definitely non-ferrous. Weight of each item suggests that they're not aluminium.

Inside my unused hard plastic caps there is a flat landing/seat that is part of the moulding and it looks to be fairly uneven. These caps would need to be twisted on tightly to achieve a good seal.

[sharkcaver]

More chance of losing the valve core I suppose if you take it out.
Also a valve body is not really designed for the core to be screwed in and out too many times I suppose.
Plus the more you mess with it the more likely it is to leak.

They are my thoughts..

Thanks Keith, this is exactly my point . Lots of supposition and not a single real world example.

The valve removal deflator keeps the valve captive, there is zero chance of losing it.
How many times is a valve stem designed to have a core removed/inserted?


Although I do agree, the more you play with something you run the risk of an unintended outcome. Real world practice in regards the deflator however provides evidence to the contrary.

People have a fear of sharks, spiders, why some even have a fear of people and public places. Like valve core deflators, the fear is real in the affected persons mind, but it is not so in the real world for most of us.

[Merts]

Lots of supposition and not a single real world example.

I gave a real world example of how those deflators don't lose valves or damage threads etc Shane.

I reckon I've used mine at least 20 times on the current set of tyres (so over 80 individual uses) and I've not had a single issue. On most trips there are several other people using them too, so my experience is several hundred deflations with zero negative outcomes.

PS. Just spoke to a mate and he has had one experience where the valve didn't screw back in properly (either cross threaded or something foreign in the thread) and it wouldn't seal 100%. He ultimately had to replace the whole valve stem assembly.
So, based on that, it is rare for things to go wrong but it can happen.

[nj swb]

After my frustration with inconsistent results from the Stauns I bought an ARB deflator for my NT. When dropping pressure a long way, it's not too bad, but the process makes smaller adjustments a moot point:

• Screw on the deflator
• Unscrew the valve core
• Deflate / check etc.
• Screw in the valve core
• Unscrew the deflator.

You can release a lot of air the old-fashioned way while all that screwing and unscrewing is going on.

I did once forget to screw the valve core back in, which was easily noticed when it flew past on removal of the deflator. I was fortunate enough to be able to find it again, and it still holds pressure OK. I also witnessed somebody else make the same mistake, so I'm pleased to know I'm not the only one who has done it. But I do have spare cores, so I'm not too concerned about the risk of it happening again.

Is the valve designed to be screwed in and out so many times? Who knows? Metal machined thread on metal machined thread shouldn't wear out too quickly, particularly given the low level of load on the thread.

Cross-threaded? How? Look at the design of the core, the location of the thread and the long length of body that will align the core inside the valve stem. Anybody clumsy enough to cross-thread that shouldn't be allowed unsupervised use of anything resembling a tool.



I believe the biggest risk would be foreign material entering the thread, but how will that happen without the operator first dropping the deflator in sand / dirt / mud? If they're going to allow foreign material to enter the thread while using the deflator they are just as likely to blow foreign material into the valve from the end of their compressor hose.

Are they the ultimate solution for deflating tyres? Not at all. Would I advise people against them? Not at all. I still carry my Stauns, and might follow OJ's lead of setting them to a slightly higher pressure, and using them as an alternative where the situation warrants.

[NJV6]

I guess the beauty about the stauns is you can put them on and by the time you get to your destination they should nearly be down to pressure.

[GHendo]

… Just spoke to a mate and he has had one experience where the valve didn't screw back in properly (either cross threaded or something foreign in the thread) and it wouldn't seal 100%. He ultimately had to replace the whole valve stem assembly.
So, based on that, it is rare for things to go wrong but it can happen.

As I said in my previous post, this is the only negative aspect I was considering. I think the deflators I have are ARB and I’ve used them a few times without any problems – however, there is always the opportunity to cross-thread the valve. I seem to run into “Murphy” quite a bit and I wouldn’t like that to happen when I was far from home. Will I continue to use them, hell “yes” – I’ll just be doubly careful when screwing the valve back – and carry a few spares.

Cheers

Geoff

[old Jack]

If you stuff a valve core up it is easy to replace but stuff a valve stem up and you need to break the bead on one side of the tyre to pull the new valve stem trough the rim.
The old fashion "T" design Schrader valve tools are a must to carry as the have 3 different tools, valve core removal, valve core thread cleaner for inside the valve stem and an external valve stem thread cleaner which is also used when pulling a replacement valve stem through the rim.

OJ.

[RUGGA]

I did once forget to screw the valve core back in, which was easily noticed when it flew past on removal of the deflator. I was fortunate enough to be able to find it again, :

+1