Identifying And Fixing A Leaking Tyre Valve Core

By NYC 10 hours ago

What happens when you can’t locate the source of a tyre puncture? Is someone playing a practical joke on you? Or is there really a problem? Learn about how you can spot the hidden leak and mend it easily.

Let’s say you have a particular tyre that occasionally needs to be pumped up every 3 or 4 weeks. You suspect it’s a puncture and send it over to your regular tyre shop. But unfortunately upon inspection, no puncture point is found and even submerging the whole wheel in water yields not a bubble. The tyre guy suggests someone might be playing a sick April Fools’ joke, refits the inflated tire then send you off, before the same symptom returns the following week.

Sounds odd but that’s exactly what I experienced for a few months until I removed that wheel for a proper cleanup after the CV-joint boot expired and spewed grease behind the rim. The culprit turned up to be a faulty tyre valve core which was easily fixed. Here’s how to identify and replace a tire valve core.

A valve core and stem from a motorcycle

Tools

• New tyre valve (I had a spare unit from my motorcycle)
• Valve core tool (valve caps with the similar end are just as good)
• Bicycle/foot pump (or you can just fill it at the nearest petrol station)
• Soap solution

Left: A proper valve core tool; Right: An almost equally functional cap

Identifying

Soap solution test

1. Remove the valve cap, then apply a layer of soap solution over the valve opening and stem.
2. A leaking valve would create bubbles and this is a sign for replacement

* The ‘traditional’ tyre shop method of using saliva as a replacement should also work

Solution Method

1.  Jack up the vehicle and make sure that the wheel is fully raised from the ground. This will help minimize the pressure applied to the wheel, thus less air escaping when the valve core is removed.

Never face straight at the valve opening when removing the core

2.  Never face straight into the valve core in the stem while unscrewing the core. It is possible for trapped foreign particles or worst the core itself to blow straight into your face.

Unscrew the core as quickly as possible minimize air leakage

3.  Quickly but carefully unscrew the valve core using the valve core tool (or sampled valve cap above). Be prepared to catch the core when it pops out due to air rushing out of the opening

4.  Quickly screw in the replacement core until it’s nice and tight.

5.  Apply some soap solution again and make sure it’s no longer leaking.

6.  Pump up the tyre to required specifications before lowering the vehicle back onto level ground.

Air pump Soap solution Valve Valve core Valve core tool valve stem