Adhesives - Tapes - Sealants - Gasket Makers

Marine Adhesives, Marine Tapes, Marine Sealants, and Marine Gasket Makers - Resources & Information

Gaskets, marine tapes, sealants, and adhesives are necessary for performing periodic service for your outboard engine and boat. From water infiltration to exposed electrical connections, PartsVu offers a complete selection of these essential products from top boating product suppliers to help you boat safely. 

Need help servicing your outboard engine? PartsVu regularly publishes helpful how-to guides and other valuable maintenance information to help boaters to service their outboard engines. Browse our outboard maintenance blog for a wide range of relevant topics and see the FAQ section below, covering everything you need to know about maintaining your boat in confidence. 

Adhesives, Tapes, Sealants, and Gasket Makers FAQ

What should I know about Adhesives, Tapes, Sealants, and Gasket Makers?

Here’s some info you need to know about Adhesives, Tapes, Sealants, and Gasket Makers:

• Never mix/match marine sealants and adhesives. While these products may serve the intended purpose in a pinch, long-term usage can spell disaster when an adhesive needs to be removed and can’t be (or a sealant unexpectedly fails during operation). For example, a hydraulic sealant is meant to withstand the high pressure needed for operation of your trim and tilt motor, but can clog internal passageways if you use it as a water pump sealant.
• Is sealant adhesive? This is a common question among new boaters, and the answer is that it depends. Sealants are generally used to prevent loss of fluids/air and block infiltration of contaminants, while adhesives are used to permanently/semi-permanently bond two surfaces together. 
• RTV tape and rtv sealants arevery useful in marine applications for electronics, fuel systems, and more. First, RTV stands for room temperature vulcanizing, which means that it begins to cure immediately upon being exposed to air. RTV tape is also water-repellent, adhesive and holds its shape, which means that you can use it to prevent small leaks (like rtv sealant for gasoline) or seal electronics when heakshrink tubing and other products are not available.
• When deciding to choose a gasket maker vs gasket, original gaskets are always the better option. Remember, most outboard engines are designed with particular tolerances, which the manufacturer created a gasket material to accommodate. While gasket makers are useful when you don’t have a gasket on hand, choose an OEM gasket when you have the option.
• Should i use gasket sealer with a gasket? To answer this question, refer to your owner’s manual and product description. In most cases, a gasket sealer is not necessary to form a seal when using a gasket - or it may even infiltrate your engine and cause damage. Plus, when it comes time to service your outboard, removing both a worn gasket and unnecessary gasket sealer is extra work. 
• Is gasket maker an adhesive? No, most gasket makers are made from silicone-based products. While there are some adhesive properties when the silicone is first applied, gasket maker acts more like a removable gasket than a permanent adhesive. 
• When in doubt, always replace marine hardware with new parts instead of adding sealants and adhesives to fix loose, leaking, corroding, or failing components. While adhesives and sealants can stop leaks, there may be deeper problems that may need to be addressed like internal corrosion or mechanical failure that even the best sealants for boats can’t fix. 

What is an outboard motor gasket?

Your outboard head gasket is a very important component in the performance and lifespan of your engine. Located between the cylinder head (where your spark plug are screwed in) and the cylinder block, a head gasket is responsible for sealing these components together to withstand the compression from the engine and enable cooling water to flow between the block and the head.

What outboard engine tools should I have onboard?

Even if you don’t do your own maintenance, all boaters need some basic boat tools in their marine tool kits to help them out of a jam. Of course, if you plan to do your own maintenance or a portion of your own maintenance, you’ll need to be a bit better equipped.

So which boat tools should you have onboard? The following are our recommendations and the reasons behind them. Of course, the tools you should have onboard are significantly dictated by the type of boating you do. As a practical matter, a near-shore, freshwater boater needs fewer tools than an off-shore boater. While a problem close to the shore can be an annoyance, a problem off-shore might be a whole different matter.

• Fuel filter wrench—good idea to have on board if you get enough water or debris in your fuel system that a fuel filter change becomes necessary.
• Adjustable band filter wrench—you may need to change your fuel/water separating filter if you have water in your system or if you got some bad gas at the marina. US marinas nearly always sell high-quality filtered gasoline, but marinas in the Bahamas are notorious for selling contaminated gasoline.
• Prop nut wrench—carrying this wrench only makes sense if you carry a spare prop. Many boaters carry a spare inexpensive aluminum prop in case they spin a hub or bend a blade so severely that it wobbles.
• Deck fill key/deck plate key/spanner wrench—these universal tools are designed to open all types and sizes of deck fill lids and shackles. Many of these tools also include bonus tools like bottle openers. Perfect for a cold one after fishing.
• Toolkit—if you have room on your boat, all-purpose toolkits can come in handy. 
• Pliers—channel lock, standard, and needle nose
• Leatherman–a very helpful all-purpose tool.
• Rigging knife
• Serrated knife—for cutting rope, your all-purpose tool might include a serrated blade.
• Flashlight
• Emergency plug set—in case a leak manifests while you are out on the water.
• Battery booster pack
• Battery terminal cleaner
• Zip ties—because we all know that you can fix almost everything with zip ties and duct tape.
• Duct tape

Does my outboard head gasket need to be repaired?

To ensure your outboard performs its best and to extend its lifespan, preventative maintenance should always be a top priority. recommends a number of regular maintenance intervals for your outboard based on its usage – 20 hours for a new engine, every 100 hours or annually, and enhanced service at 300 hours and 500 hours.

However, one common benchmark for outboard head gasket replacement many boaters miss is replacing it every four (4) years. Depending on your usage, this timeframe may be shortened but four years is generally regarded as a “must” to change your head gasket before other problems develop.

There may be no visible signs of head gasket damage by this time, but this repair will give you peace of mind – plus, when you’re changing the head gasket, you can perform other inspections and replacements (such as anodes, engine bores, salt/sand buildup, spark plugs).

Another common sign that your  outboard head gasket is in need of repair is low pressure in the cylinders. This requires a simple compression test on each cylinder, which involves removing each spark plug, plugging in a compression gauge, and cranking your engine without giving it throttle.

What you’ll be looking for as you test each cylinder is near-identical readings between cylinders. If there’s more than 10% variance between each cylinder, it’s likely that the head gasket is the culprit.

If you notice black specks, a blackish crud, or a grey slime in the cylinder, it’s more than likely that a leaking head gasket is to blame. The reason for these substances is that combustion byproducts build up in the combustion chamber during combustion. These byproducts then either flake off (specks), build up inside the cylinder (crud), or mix with water from the adjacent cooling chamber (slime).

When idling, especially at low RPMs, you may notice that your engine runs too slow – almost to the point of completely dying. Or, it may provide a rough idle that’s not consistent, causing a jarring motion.

The reason for these events is that the spark plugs cannot create a consistent spark due to water leakage on the spark plugs. If you remove the spark plugs and notice corrosion, then water is leaking in and diluting the fuel due to a faulty head gasket.

Can you replace a head gasket yourself?

Yes, a head gasket repair is an easy job that only requires a few tools. Unlike a vehicle, where getting to the head gasket requires the removal of the engine and other components, an outboard is smaller and easy to access.

How much does it cost to replace a head gasket on a boat?

If you choose to replace your outboard head gasket yourself, you can only be on the hook for parts ($50 or less for many engine models) and tools (many of which you may already have in your toolbox).

Taking your outboard to a mechanic will include the cost of parts, but also labor. Considering labor generally costs between $70 – $120 (or more!), the total cost of just a head gasket replacement can be a few hundred dollars. Of course, the advantage of a head gasket replacement by a mechanic is that they can make other replacements, trim the heads if they’re warped, and diagnose any other developing issues that may be plaguing your outboard.

Is a head gasket worth fixing?

Yes, a head gasket is a worthwhile investment that can prolong the life of your entire outboard motor. Better yet, you can learn an essential maintenance skill and expand your knowledge base, both of which will pay you dividends in the future.

What is an outboard leak down test?

An outboard leakdown test is a simple diagnostic checkup for your outboard – and it can even be incorporated into your regular maintenance intervals for peace of mind. 

During the test, you’ll be able to determine if there’s any loss in air pressure around your engine’s internal seals and passages. Even a pinhole leak can drastically alter your outboard’s performance, so performing a leak down test is important to determine whether the piston seals and other components are in good shape. 

Fortunately, a leak down test only requires a few common tools and some basic knowledge about your outboard. Even boaters with minimal experience can diagnose developing issues that affect the overall performance and lifespan of your boat’s engine(s). Best of all, performing this test will save you money and headaches down the road.

A outboard leak down test indicates the condition of each of the engine’s cylinders and the overall condition of the motor. Similar to a compression test, it involves spraying compressed air into each cylinder and using a pressure gauge to measure a percentage of pressure that’s lost after a short period.

Also, part of doing a leakdown test on a motor is to listen for any signs of leakage. By listening closely to each cylinder and the areas around them, you’ll better understand where leaks may be present.

The goal of a pressure test is to confirm whether the motor has any air leaks. The presence or absence of air in engines often leads to leaking of fuel-air mixtures and leakage of fuel during operation. 

Additionally, these leaks may become infiltration points for water and moisture from the aquatic environment, resulting in internal corrosion, sub-optimal performance (i.e., at idle, low RPMs, and high RPMs), and other issues.