Masterparts stocks high-quality welch plugs, suitable for almost all automotive makes and models.
These plugs are also sometimes called core plugs or freeze plugs.
Welch plugs are thin discs made from brass or galvanised steel. They seal the sand casting holes in the engine block, and prevent coolant or water from leaking out of the coolant cavities.
When there’s insufficient antifreeze in the cooling system and the coolant freezes and expands, welch plugs are designed to pop out.
Structural damage to the engine can be prevented in this way.
The primary function of a welch plug is to block the holes used in the engine’s sand-casting process.
Plugs are pressure-fitted into the casting holes with the blow of a hammer. The force of the blow causes the convex side of the plug to collapse, expand and seal the hole.
Welch plugs are susceptible to corrosion. Poor fitment and failure to properly maintain a vehicle’s cooling system can both hasten the corrosive process. This can cause the plugs to leak.
The main sign of a damaged welch plug is coolant or water leaking from the side of the engine, or between the engine and transmission.
Replacing welch plugs is a task best left to an experienced mechanic. This is partly because a leak could have many other sources and partly because the plugs may be difficult to access.
In some vehicles, welch plugs are fairly easy to get to. In others, various engine parts – or even the entire transmission – may have to be removed to access them.
Once it’s accessible, removing a welch plug involves using a hammer and screwdriver to tap the plug so it pops out of place and then prying it out. It’s important not to damage the surface of the hole where the plug sits, to prevent subsequent leaks.
The hole should then be sanded clean, to remove corrosion and old sealant.
A new welch plug, with some sealant, can then be carefully hammered into place using a suitable tool.
The following resources offer some guidance on how to replace welch plugs:
Masterparts offers welch plugs ranging from 14 mm to 56 mm (or ¾ to 2¼ inches).
We offer door-to-door delivery. Alternatively, visit any of our branches across South Africa or in Windhoek, Namibia.
Welch plugs in and around Cape Town:
Welch plugs in KwaZulu-Natal:
Welch plugs in Namibia:
Masterparts stocks welch plugs, along with a huge range of other automotive parts and spares, for most vehicles on our roads. Contact us if there’s a part you need and we’ll do our best to help.