Countertalk: Knowledge Building: Removing Gaskets

There are few areas of the engine business that will cause more grief than having a newly installed cylinder head leak like a sieve around the gasket.

Invariably, it is the machine shop or the gasket that takes the blame, but the reality is that often it’s the surface finish on the engine block, which never made it to the machine shop, that is to blame.

Certainly, in cases of extreme engine failure, the entire engine should have made its way to the rebuilder, but in cases where the technician judges the failure to be cylinder-head-specific, or when other components such as an intake manifold are involved, it is often up to the technician to prepare the mating surface.

Years ago this was simply a matter of spraying with various chemicals and putting some good old elbow grease to work with a raft of scrapers.

This was no easy task. The combination of heat, pressure, and engine fluids can cause gaskets to bond so tightly to steel or cast aluminum that they are very difficult to remove. This problem can occur whether the gasket in question is made of cork, paper, or form-in-place material.

The search for better methods of removal eventually led to various methods aimed at reducing the frustration factor.

Impatience with the task can potentially lead to unintended damage. This became increasingly important in recent years with the use of lighter aluminum alloys. So when a technician is faced with a gasket removal challenge, the best tool for the job should be used.

There are four primary gasket removal tool options:

1. Surface conditioning disc

2. Plastic bristle disc

3. Gasket removal disc

4. Hand scraper

Regardless of the method selected, gasket removal will generate particles that can drop inside a manifold or other component and seriously damage moving parts when the engine is put back in service. Before you start, be sure to plug openings to prevent this from happening.

Surface Conditioning

This is the quickest, most effective and most commonly used means for getting rid of pesky gasket residue. It consists of an abrasive-coated non-woven material.

An abrasive surface conditioning disc may be operated at up to 25,000 RPM, and poses the risk of rounding or otherwise distorting mating surfaces and thus spoiling the seal. Overly aggressive abrasives can also threaten thin metal components such as the gasket seat on a valve cover. When using a surface conditioning disc to clean away gasket residue one should take it slow, and be careful to remove only the gasket and not the underlying surface.

Bristle Disc Removal

A bristle disc is a tough plastic brush with an abrasive imbedded in the bristles or fingers, designed to be used with a rotary tool at approximately 20,000 RPM. The plastic fingers wear as they clean to continually expose fresh abrasive. This cleaning method replaces scrapers and wire wheels, and eliminates the danger of broken and flying wires. It takes more time to remove gasket residue with this method than with a surface conditioning disc, but there is less chance of wearing away metal surfaces. It is important to plug openings and clean away any residue generated with this process.

Gasket Removal Disc

Like the surface conditioning disc, gasket removal discs are made with a non-woven material. This is the least aggressive and thus the slowest of the automated gasket removal methods, but it can be used without concern for damage to metal surfaces.

Hand Scraping

The oldest method to remove an old gasket is to manually scrape away stuck segments with a putty knife or scraper. It can be a slow, frustrating process, depending on how tight the bond is between gasket and metal, and there is danger of gouging the metal (or yourself) in the process. A chemical solvent can be used to help loosen the gasket, which can make the job easier.

Regardless of the method of choice, it is important that the surface finish not be damaged. Smoothed edges, wavy surfaces, and major gouges will all compromise the integrity of the seal.

The key to success is a patient approach and a firm understanding of how important this deceptively simple labour-intensive job really is.

Special thanks to 3M Automotive Trades for information and photos used in this article.