Cylinder Block

Servicing Sand Holes or Porous Engine Castings

Porosity or sand hole(s), which will cause oil seepage or leakage, can occur with modern casting processes. A complete inspection of engine and transmission should be made. If the leak is attributed to the porous condition of the cylinder block or sand hole(s), service can be made with an epoxy sealer meeting specification M3D35-A(E) or equivalent. Do not service cracks with this material. Service with this metallic plastic must be confined to those cast iron engine component surfaces where the inner wall surface is not exposed to engine coolant pressure or oil pressure. For example:

1. Cylinder block surfaces extending along the length of the block, upward from the oil pan rail to the cylinder water jacket, but not including machined areas.
2. Lower rear face of the cylinder block.
3. Intake manifold casting. Service is not recommended to the intake manifold exhaust crossover section, since temperatures can exceed the recommended temperature limit of 260°C (500° F).
4. Cylinder front cover on engines using cast iron material.
5. Cylinder head, along the valve rocker arm cover gasket surface.

The following procedure should be used to service porous areas or sand holes in cast iron.

1. Clean surface to be serviced by grinding or rotary filing to a clean bright metal surface. Chamfer or undercut hole or porosity to a greater depth than rest of cleaned surface. Solid metal must surround hole. Openings larger than 6.35mm (1/4 inch) should not be serviced using metallic plastic. Openings in excess of 6.35mm (1/4 inch) can be drilled, tapped and plugged using common tools. Clean service area thoroughly. Metallic plastic will not stick to a dirty or oily surface.

2. Mix metallic plastic base and hardener as directed on container. Stir thoroughly until uniform.

3. Apply service mixture with a suitable clean tool (putty knife, wood spoon, etc.) forcing epoxy into hole or porosity.

4. Allow service mixture to harden. This can be accomplished by two methods. Heat cure with a 250-watt lamp placed 254mm (10 inches) from serviced surface, or air-dry for 10-12 hours at temperatures above 10°C (50°F).

5. Sand or grind serviced area to blend with general contour of surrounding surface.

6. Paint the surface to match the rest of the block.