Improper Engine Gasket Cleaning Methods Using Surface Conditioning Discs

When cleaning engine gasket sealing surfaces or cleaning parts from an engine that are to be reused, it’s critical to not use surface conditioning discs, such as abrasive pads or bristles. These discs can cause damage to the sealing surface or generate debris that will cause damage to bearing surfaces in cast iron and aluminum engine blocks.

 

TIP: Dealerships that use improper gasket cleaning methods that result in engine failure will be debited the cost of the replacement and repair.

 

Abrasives Cause Engine Damage

 

Abrasive pad or bristle devices (Fig. 8) — typically made of woven fiber or molded bristles — should not be used because:

  • Abrasive pads will produce fine grit that the oil filter will not be able to remove from the oil. This grit is abrasive and may cause internal engine damage. Abrasive pads can easily remove enough material to round cylinder head surfaces, which can affect the gasket’s ability to seal, especially in the narrow seal areas between the combustion chambers and coolant jackets.
  • Abrasive pads, wire, and rubber finger wheels can remove enough metal to affect cylinder head, block, oil pan rail, and intake manifold runner flatness, which can cause coolant and oil leaks and air leaks. It takes about 15 seconds to remove 0.203mm (0.008 in.) of metal with an abrasive pad.
  • Abrasive pads, rubber finger wheels and wire wheels with high-speed grinders produce air-borne debris that can travel throughout the shop and contaminate other work being performed outside of the immediate work area.

 

Fig. 8

 

When using surface conditioning discs that contain abrasives, aluminum oxide (a common component of sandpaper) is dislodged from the disc along with metal particles from the engine component. Even the finger-type discs, which don’t appear to have any type of abrasive material, contain aluminum oxide. The presence of aluminum oxide in engine oil has been shown to cause premature engine bearing failure, in some cases, in as little as 1,367 miles (2,200 km) or less after the repair has been made.

 

Surface conditioning discs also may grind the component material and imbed it into the disc when more aggressive grinding of the gasket surface takes place.

 

Any debris from these surface conditioning discs cannot be properly cleaned from the oil passages with shop air or solvents.

 

Recommended Cleaning Procedures

 

GM recommends the use of a razor blade or plastic gasket scraper to clean the gasket surface on engine components that are to be reused. When using a razor blade-type gasket scraper, use a new razor blade for each cylinder head and corresponding block surface. Hold the blade as parallel as possible to the gasket surface to ensure that the razor blade does not gouge or scratch the gasket surfaces. Do not gouge or scrape the combustion chamber surfaces or any engine-sealing surface during the cleaning process.

 

To properly clean the sealing surface prior to reassembly, GM Low VOC Cleaner, part number 19287401 (in Canada, part number 88901247), should be sprayed on the mating surface. Avoid getting solvent in any area other than the mating surface to be cleaned. Allow it to soak in for several minutes to loosen old RTV sealer/gasket material.

 

TIP: GM recommends using a plastic razor blade or non-metallic scraper to remove all loose sealer/gasket material.

 

When cleaning engine components, the feel of the sealing surface is critical, not the appearance. After all the gasket material is removed, there will be indentations from the gasket left in the cylinder head. The new gasket will fill these small indentations when it is installed.

 

For additional information, refer to GM Bulletin #00-06-01-012F.

 

– Thanks to Tracy Lucas

 

 

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