Replacing disc type core plugs "Freeze plugs"
Volvo 140, 164, 121, P1800, PV, 200, 300, 700, 900
22.12.2021We show the renewal of a disc type core plug "freeze plug" with simple tools. The repair has been done on a Volvo B20 engine block. Please note that these instructions can only be used for disc type frost plugs. In the case of cylindric plugs, it must be noted that the core hole has no inner edge where the frost plug rests. Therefore, the plug may accidentally fall into the engine block during the procedure shown here.
Water leakage caused by a broken plug.
Drain the engine block.
The older Volvo petrol engines have a drain tap next to the oil filter. This is simply opened with an open-end wrench. Place a hose on the tap to channel the cooling water into a collection container.
Hammer a chissel or a durable screwdriver through the broken plug. A short and heavy hammer is a good choice. Caution: Do not hammer in too far!
Lever out the broken plug.
Clean the sealing surface at the engine block.
Apply some sealing compound to the sealing surface. Put in the core plug with curvature outwards.
The disc core plug is spread by deformation / "flattening" of the curvature and thus clamps itself. Use a short and heavy hammer and a pressure piece which has approximately half the diameter of the core plug. We used a short, solid brass rod. Put the pressure piece straight on and try to flat the curvature with one single blow if possible.
- All notes serve only as an example and do not replace the workshop instructions of the automobile manufacturers! All information is supplied without guarantee!