Gaskets play a vital role in engine operations. They create a physical barrier between two parts. The gasket prevents things like dust and dirt, fluids, gases and electrostatic discharges from prohibiting your engine from running at peak efficiency.
The best gasket in the world is useless unless properly installed and sealed. Incorrect gasket application can ruin an otherwise perfect engine build or reassembly.
By avoiding these common gasket application mistakes, you can eliminate the risk of poor engine performance and potentially acute damage.
Indications of Gasket Failure
Your first sign of a failing gasket is when, despite the absence of a visible leak, you begin to lose coolant. Your Check Engine light will activate on your dashboard. Your engine may heat up, or the cylinders could misfire.
When this happens, the cylinder head can squeeze the gasket further, causing it to fail. This failure may lead to further cracks in the surfaces, permitting coolant, gasses or other materials to harm the engine.
What Causes Gasket Failure
Gasket failure rarely happens due to the gasket design itself. Blown gaskets occur due to poor installation, or the fasteners, torque procedure or block designs preventing the gasket from doing its job. In NASCAR, for example, ignition issues often cause a gasket to blow. Torque wrenches improperly calibrated, wrong types of fasteners or something else that causes uneven clamping may result in a leak.
Manufacturers construct gaskets from a variety of materials, depending on the industry and the need. They usually come in the shape of a ring or sheet. Creating a compression seal, the intention of a gasket is to resist temperature, electric or electrostatic changes, along with undesirable liquid and gas leakage.
Hence, using and applying the right sealant will make the difference between a 100% reliable gasket and one that will most likely fail.
Most materials used for gaskets are either soft metals or elastomers. However, some have metal coatings for strength and durability. Aluminum, copper, graphite, cork, rubber, polyurethane and silicone are among some of the common types of substances that manufacturers found to make the best gaskets. You want the material to be malleable and conform to the shape of the two surfaces that it protects from contamination.
Gaskets have many uses in many industries. One of the primary applications of a gasket is to keep liquids out of certain parts of a system. Some gaskets offer better resistance to chemicals, and therefore may be used in the food industry. Manufacturers design other gaskets to seal out oils, lubricants and solvents, but most are seen in car engines.
Environmental seals are gaskets designed to seal out dust or other particulate matter. Electrical enclosures use these sorts of gaskets, as do laboratories, hospitals and other places where you need to strictly control the environment.
Some gaskets have anti-vibration features for use in machinery mountings or structural bearings.
One of the key characteristics required of a gasket is its ability to tolerate compressive loads. Manufacturers use a hot compression test to determine the specific weights and temperatures that a gasket can endure.
The tests include stressing the gasket beyond the normal limits to see the high-end of the design’s tolerance. Temperatures are increased gradually over a set period. Decreases in the gasket material’s thickness are carefully measured.
Manufacturers must use many distinctive designs to meet the exact requirements of usage. You can find spiral, double-jacket, octagonal, rectangular and more. The specifications vary considerably. For example:
Inexpensive solid gaskets have high-pressure and thermal-resistance ratings. However, the effectiveness of these gaskets lessens considerably if the surfaces against which they form a seal are harder than the metal coating.
The spiral wound gaskets combine soft plastics or rubber with some kind of metal. Often, these types have layers of material, which increases their strength. Spiral wound gaskets have exceptional stress and thermal resistance characteristics but are also flexible and, with the right adhesive, seal well. Companies use these gaskets in pumps and heat exchange systems.
Jacketed gaskets come in singles or doubles. A single jacket only has a metal coating on one side, while the double jacket types have metal coatings on both sides. The inner material is either rubber or plastic. Jacketed gaskets have a variety of styles available, too, depending on use.
One of the best types of gaskets for extreme temperatures is the silicone gasket. In addition to temperature resistance up to 480 degrees Fahrenheit, they also resist ultraviolet light. This makes them ideal for outdoor use. Made of foam or sponge, the electronics and transit industries often employ them.
There are many more types of gaskets, so consult the manufacturer’s guidelines before deciding which one is best for your needs.
Incomplete Surface Preparation
For any gasket application, you must carefully clean and prepare both surfaces between which you will place the gasket. Remove any pieces of the old gasket and any old glue or adhesive.
Never use a razor blade or anything that could scratch the surface. Any scratches may provide a channel or means for fluids or gasses to leak through. Use a brush or scrapper made of plastic or nylon, although it is probably best to use a chemical cleaner.
Applying the Wrong Amount of Sealant or Gasket-Creator
Using too much sealant is as bad as using too little. Too much may clog other areas of the engine, while too little may mean an inefficient seal.
Applying gasket-creating material and sealants takes experience. However, for most purposes, start by using a bead thickness of around 1/8″. Apply the sealant evenly in a continuous bead to each surface.
Make sure you use the right type of sealant or lubricate, like Vibratite, so you don’t have a catastrophic failure due to leakage.
Using the Wrong Type of Gasket Maker
Each application requires very specific types of gasket makers. Do your research. Liquid gasket makers have very specific designs, depending on the use. Some, for example, have higher temperature resistance, while others may be better suited for sealing out gases under certain operating conditions.
Using Aerobic Gasket Makers for Gasoline-Powered Machines
Many mechanics forget that gasoline breaks down aerobic sealants quickly. These sealants should never come in contact with gasoline, whether during assembly or operation.
For cars, trucks, gas-powered tools and the like, always use a solvent-based gasket maker.
Insufficient Curing Time for Solvent Based Gasket Makers
Never scrimp on the curing or drying times when you apply a solvent-based gasket maker or flange sealant. If you do, the integrity of the seal is often compromised.
When you use a standard silicone sealant, the curing time can be anywhere from two hours to a full day. If the job calls for anaerobic sealant, the curing time typically takes about an hour.
Certain types of silicone sealants cure quicker, so make sure you read the instructions before beginning work.
Using Gasket Maker as a Sealant or Means of Holding a Standard Gasket in Place
Gasket maker or silicone sealant should never be used as a glue or means of keeping a gasket in position when you reassemble your engine. Mechanics often do this believing, erroneously, that a gasket maker will not only hold the gasket in place, but it will add to the seal.
Gasket makers use a very thick formula that is unsuitable for this sort of application. Using these runs the risk of ruining the seal, creating gaps and requiring you to re-install the gaskets.
Using Less-Expensive Head Gaskets Than Recommended
It is not a good idea to try and save money and use a less-expensive version of the manufacturer’s recommended head gasket. Attempting to apply, for example, a non-MLS (multi-layered steel) head gasket when the equipment calls for an MLS head gasket will significantly reduce the longevity, given the required tolerances in the engine.
OEM MLS Head Gaskets Are Not Necessarily the Best Replacement Gaskets
If industry publications and authority websites indicate that the manufacturer’s original gasket has some weaknesses, then an aftermarket MLS gasket may provide you with a better, longer-lasting replacement.
Original equipment gaskets often require a mirror-smooth surface for the head and block of an engine. Plus, aftermarket gaskets have thicker surface coatings that will seal better against the imperfections that develop after miles of wear and corrosion.
Using Anaerobic Gasket Makers to Fill Gaps
Anaerobic gasket makers are not made to fill large gaps. Generally, if the gap is between 15-20 thousandths of an inch, you can use an anaerobic gasket maker or flange sealant.
Use a silicone or RTV gasket maker for larger gaps. These will seal tighter, without any air pockets.
Letting Non-Solvent Gasket Makers Partially Dry Before Assembly
Unless you must use a solvent-based gasket maker, do not allow the solvent to partially dry (a common misconception among mechanics). If you use an anaerobic gasket maker or sealant, assemble the parts immediately while it is still wet.
The curing process for these types of gasket makers, you need to cure them without oxygen.
Reusing Toque-to-Yield (TTY) Head Bolts With MLS Head Gaskets
Many times, mechanics will reuse the TTY head blots that you must disassemble when replacing an MLS head gasket. It is an easy mistake to make or something that a lazy mechanic might do since the MLS head gaskets do not come with new bolts. You must buy them separately.
The weakened condition and reassemble stress risks breakage if you do not replace them.
Replacing Only One Gasket
Backyard mechanics often make the mistake of only replacing one gasket, rather than the complete set. It is better to apply new gaskets for the entire assembly at one time. That way, you have less chance of an additional failure in the near future.
Using a Sealer Improperly
Some new gaskets may contain special chemical sealants that will break down if the sealants come in contact with other types of sealants. Pay careful attention to the type of gasket application that you choose to install.
For example, coated gaskets, which do not require sealants, can quickly deteriorate if you also use silicone sealant. The silicone may not bond and can leak into the combustion chamber or cooling jackets.
Mechanics and car dealerships often want to help their customers as much as possible. This means getting your vehicle back in service as quickly as possible.
With gasket applications, you risk a disaster and another trip sooner, rather than later, back to the garage. Paying attention to all the steps required when replacing a gasket, including types, curing times and manufacturer’s recommendations, may add time to the work, but it will save time, frustration and money in the future.
Wrong Gasket Material
Even when paying attention to the manufacturer’s parameters regarding gaskets and gasket application, you have a choice of materials.
For example, you can use composite for a stock engine. Use a single-layer embossed steel shim if you want to increase your compression ratio and power. A performance engine with aluminum cylinder heads works best with a composite with a copper wire ring.
Use multi-layered steel for a race car or high-horsepower street vehicle that has a forced induction engine.
Poorly Organized Work Shop
Nothing provides you with more opportunities to make mistakes when working on engines and gaskets than a poorly organized garage or workshop. Keep your garage clean and organized. During disassembly, organize the parts by what you will dispose of and what you plan on reusing.
Clean all parts before gasket application and organize your cleaning materials accordingly.
If you do not maintain a clean and orderly work environment, you risk disaster.
Taking your time and avoiding the mistakes listed here will save you time, money and lots of frustration. Applying the correct methods and doing your research ahead of time will ensure a quality installation every time.