Flexlite GX 403W Parts FAQs
Spares for a water-cooled MIG torch: what to check on the cooling side, the neck and the front end, and how to choose and fit parts.
What extra checks does a water-cooled MIG torch need compared with an air-cooled one?
On top of the usual tip, nozzle and liner checks, look after the cooling circuit. Check the coolant level regularly, look at the colour of the coolant (discolouration suggests contamination), and inspect hoses and connections for chafing, kinks and small leaks.
Let coolant reach the front of the torch before you start welding, and make sure the lines are not kinked or pinched. Weak flow, a blocked filter or low coolant can overheat internal parts quickly, so follow the machine and torch maker's instructions for flow.
What coolant should I use in a water-cooled torch?
Use the coolant the torch and cooler maker specify. It is generally a low-conductivity coolant made for welding, not plain tap water, because dissolved minerals make it conductive and can cause corrosion and blockages.
Coolant ages, so many makers advise testing or replacing it on a regular schedule, and the interval and limits depend on the equipment. Do not mix coolant types, and do not use automotive antifreeze unless the maker says it is suitable. Check the manual for the correct type and change interval.
How do I spot and fix a coolant leak at the neck?
Look for dampness around the neck connection, drips under the torch, or coolant at the rear connection. A common cause is a dried, cracked or flattened O-ring, which can appear after many heat cycles or when the neck has been changed several times.
Switch off and let the torch cool, then check the O-rings, lubricate them lightly and replace any that are dry or cracked. A coolant leak can also cause arcing inside the torch and spoil the weld, so stop welding and fix it before carrying on. Follow the manual for the correct O-ring type.
Why do my contact tips overheat or discolour on a water-cooled torch?
Common causes are a tip that is only hand-tight, which creates resistance and heat; a tip bore that is too large for the wire, which causes micro-arcing; and a front end that is loose or dirty. Blue or purple threads on a removed tip suggest it was running hot because it was not tight enough.
Tighten the tip with the correct tool to the maker's guidance, check the diffuser and tip holder bores are free of spatter, and make sure coolant is flowing properly. Do not file the bore.