Mercury Corrosion Inhibitors and Mercury Grease FAQs
Note that fittings can be contaminated by salt – especially the ones near the steering tube – so replace them if they are too corroded to accept grease. Watch as you pump fresh grease into the fitting and see if old, dirty grease or water or both push out from the corresponding space. Ideally, these cavities are filled with clean grease all the time. A light coating of grease on the tip of the trim rams will reduce friction there as well. If your engine is equipped with stainless balls on the tips of the trim rams, work the balls to get the grease inside their cup.
If your prop was not removed for the gear lube change, remove the cotter pin or lock washer from the propeller and loosen the prop nut. Exercise extreme caution as prop blades can be very sharp. With the nut loosened, remove the propeller and associated prop hardware to inspect the propeller shaft.
Look for fishing line that may be behind the prop and near the prop shaft oil seals. Remove any line and if the seals are intact, apply a fresh coating of Mercury 2-4-C grease to the propeller shaft before reinstalling the prop. Tighten and use a new cotter pin to complete the installation if applicable.
Be aware that your boat’s propeller functions like your vehicle’s tires. Wear on the edges of the propeller can reduce traction, causing speed and fuel efficiency loss. Propeller reconditioning or replacement should be considered if you note wear, rounded edges, thin blades, or cracking. You should also inspect, and replace as needed, the hub inside the propeller. Cracking or wobbling can indicate a worn or damaged hub.
This is also a great time to inspect your external engine anodes. Anodes worn beyond 50 percent should be replaced. Be sure to select the correct sacrificial alloy. The proper sacrificial alloy will depend on whether you boat in salt or freshwater. Spend an extra couple of minutes to check fitment because different propeller selections will not work with all anodes.
On the powerhead itself, corrosion inhibitor can be liberally applied to the metal surfaces, taking some care to avoid the air intake itself. We recommend Boeshield’s T-9 brand, but any high-quality marine corrosion inhibitor will help. If any salt residue exists on the engine, rinse with a light stream of fresh water before applying T-9. This product also works well on battery connections, fuel/water separator bases, and trailer parts.
If you have exposed metal surfaces on your lower unit, trim assembly, steering tiller arm, or trim motor itself, consider purchasing a can of Mercury’s Corrosion Guard to supplement paint on these surfaces.
Note that fittings can be contaminated by salt – especially the ones near the steering tube – so replace them if they are too corroded to accept grease. Watch as you pump fresh grease into the fitting and see if old, dirty grease or water or both push out from the corresponding space. Ideally, these cavities are filled with clean grease all the time. A light coating of grease on the tip of the trim rams will reduce friction there as well. If your engine is equipped with stainless balls on the tips of the trim rams, work the balls to get the grease inside their cup.
If your prop was not removed for the gear lube change, remove the cotter pin or lock washer from the propeller and loosen the prop nut. Exercise extreme caution as prop blades can be very sharp. With the nut loosened, remove the propeller and associated prop hardware to inspect the propeller shaft.
Look for fishing line that may be behind the prop and near the prop shaft oil seals. Remove any line and if the seals are intact, apply a fresh coating of Mercury 2-4-C grease to the propeller shaft before reinstalling the prop. Tighten and use a new cotter pin to complete the installation if applicable.
Be aware that your boat’s propeller functions like your vehicle’s tires. Wear on the edges of the propeller can reduce traction, causing speed and fuel efficiency loss. Propeller reconditioning or replacement should be considered if you note wear, rounded edges, thin blades, or cracking. You should also inspect, and replace as needed, the hub inside the propeller. Cracking or wobbling can indicate a worn or damaged hub.
This is also a great time to inspect your external engine anodes. Anodes worn beyond 50 percent should be replaced. Be sure to select the correct sacrificial alloy. The proper sacrificial alloy will depend on whether you boat in salt or freshwater. Spend an extra couple of minutes to check fitment because different propeller selections will not work with all anodes.
On the powerhead itself, corrosion inhibitor can be liberally applied to the metal surfaces, taking some care to avoid the air intake itself. We recommend Boeshield’s T-9 brand, but any high-quality marine corrosion inhibitor will help. If any salt residue exists on the engine, rinse with a light stream of fresh water before applying T-9. This product also works well on battery connections, fuel/water separator bases, and trailer parts.
If you have exposed metal surfaces on your lower unit, trim assembly, steering tiller arm, or trim motor itself, consider purchasing a can of Mercury’s Corrosion Guard to supplement paint on these surfaces.
Use a filter wrench to loosen the existing filter element and use caution when removing it as it will be filled with gasoline. A clear plastic or glass container is helpful to dump the filter and examine the contents. A small amount of debris is common, as is a small amount of water after the fuel has had a moment to settle. More significant amounts of water would warrant further investigation.
Move back to the engine and locate the filter element(s) on the engine. The scope of this service will only include the low-pressure fuel filter and fuel water separator if applicable by model. Mercury recommends that owners do not service their high-pressure fuel filters. Depending on your engine model, the water separator filter (or castle filter) may be removed by using a wrench, standard tools, and a little caution. Unplug the water-in-fuel sensor if applicable and spin the cap off of the housing. Replace the filter element with a fresh one, lube the o-ring with grease or oil, and carefully reinstall the cap.
Locate your Mercury engine’s primer bulb if applicable and use the primer to pump up the fuel system. You should feel and hear gasoline entering and filling the filter cup. Check for leaks and prime until the bulb becomes firm.
If you are not already regularly running Mercury Quickare and/or Quickleen through your Mercury fuel system, the 100-hour service interval is an excellent time for a “shock treatment.” Quickare is a fuel system cleaner and top-lube that will help to clean deposits from the tank, lines, carburetors, injectors, and pumps. It breaks up fuel system varnish and will help to prevent gumming.
Quickleen is a fuel system conditioner that also helps to remove carbon deposits. The standard dose is one ounce per ten gallons, but if you are not running the product regularly, you can double that ratio for more cleaning power. Pour the products into the fuel tank fill and run the boat. No additional work is needed. It is a great idea to inspect your fuel tank fill’s o-ring for damage when you add fuel or additives as a damaged o-ring can allow water from rain or boat washing into your fuel system.
Where can I learn more about Mercury Outboard Engine Parts?
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Read up on the latest developments in boating, as well as search for everything you need to know about Mercury boat engine maintenance.
To get you off to a good start, these are some of the most important articles on Mercury Corrosion Inhibitors & Grease, how to grease a MerCruiser engine, choosing from the best outboard maintenance products on the market, and more:
What is Mercury Precision Care?
Mercury Precision Care is a program offered by Mercury Marine that provides extended service coverage for new and used Mercury outboard engines. Mercury Precison Care offers a range of service plans that provide coverage for a variety of repairs and maintenance needs, including repairs for engine components, electrical systems, fuel systems, and more. The program is designed to provide peace of mind to Mercury outboard owners by helping to protect their investment and ensure that their engine is running smoothly for years to come.
Shop PartsVu for Mercury Precision Lubricants | Corrosion Guard
How do I use Mercury Corrosion Guard?
Mercury Corrosion Guard is a protective spray that helps to prevent rust and corrosion on metal surfaces, including those found on your Mercury outboard. Here are the general steps to use it:
- Clean the Surface: Before applying the Corrosion Guard, clean the surface you wish to protect using soap and water. Remove any dirt, grime, or other debris that may be present.
- Dry the Surface: Once the surface is clean, dry it thoroughly using a clean, dry cloth. Make sure the surface is completely dry before applying the Corrosion Guard.
- Apply the Corrosion Guard: Hold the can of Corrosion Guard about 6 to 8 inches away from the surface and spray a thin, even layer over the metal. Avoid over-applying the product as this can cause the surface to become sticky or attract dirt and debris.
- Let it Dry: Allow the Corrosion Guard to dry completely before using or storing your equipment. This typically takes around 30 minutes, but can vary depending on the temperature and humidity of your environment.
- Reapply as Needed: Reapply the Corrosion Guard every few months or as needed to maintain the protection of the metal surface.
It's important to note that Corrosion Guard should only be applied to external metal surfaces and should not be used on internal engine components or electrical connections. If you are unsure about where to apply the product or have any other questions, consult the manufacturer's instructions or contact a professional mechanic.
What does the "2 4 C" stand for in Mercury Marine 2-4-C Grease?
The "2 4 C" in Mercury 2 4 C Grease stands for "2 and 4 cycle" engines. This type of Mercury Marine Grease is specifically designed to meet the unique lubrication needs of both two-stroke and four-stroke outboard engines. The formulation of the grease is optimized for the harsh marine environment, and it provides excellent resistance to water washout, corrosion, and extreme temperatures. It is commonly used to lubricate a variety of components on Mercury outboard engines, including steering systems, throttle and shift cables, and pivot points.
How long does Mercury anti corrosion grease last before I need to reapply it?
The longevity of Mercury anti-corrosion grease can vary depending on a number of factors, including the specific product used, the application method, and the conditions in which the boat is used. Generally speaking, however, Mercury anti-corrosion grease is designed to provide long-lasting protection against corrosion in harsh marine environments. In many cases, a single application of the grease can provide protection for the entire boating season.
That being said, it's always a good idea to periodically inspect the components that have been treated with anti-corrosion grease to ensure that the grease is still providing adequate protection. If you notice any signs of corrosion or if the grease appears to be wearing thin, you may need to reapply the grease to maintain protection. It's also important to follow the manufacturer's recommendations for application frequency and method, as this can help ensure optimal performance and longevity of the grease.
How often should I be checking and cleaning Mercury battery corrosion?
Regular battery maintenance is an important aspect of keeping your Mercury outboard engine in good condition. Battery corrosion can occur when acidic vapor from the battery reacts with the metal components surrounding the battery. If left unchecked, battery corrosion can cause damage to the battery terminals and surrounding components, and it can even impact the performance of the engine.
To prevent battery corrosion, it's a good idea to perform periodic checks and cleanings of the battery terminals and surrounding components. The frequency of these checks and cleanings will depend on a number of factors, including the age and condition of your battery, how often you use your boat, and the conditions in which you operate your boat.
As a general rule, it's a good idea to check your battery at least once a month, especially during the boating season. You can check for signs of corrosion by inspecting the battery terminals and cables for any buildup of white or greenish residue. If you notice any corrosion, you should clean the affected areas using a mixture of baking soda and water, and then rinse the area thoroughly with clean water. You can also apply a corrosion inhibitor or a battery terminal protector to help prevent future corrosion.
Is it possible that Mercury antifouling paints can cause galvanic corrosion?
Mercury antifouling paints are designed to help prevent the growth of marine organisms on the hulls of boats and other watercraft. While these paints are generally safe and effective for use in marine environments, it is possible for them to cause galvanic corrosion in certain circumstances.
Galvanic corrosion occurs when two dissimilar metals come into contact with each other in the presence of an electrolyte, such as saltwater. When this happens, an electrochemical reaction can occur, which can cause one of the metals to corrode more quickly than it would otherwise.
In the case of antifouling paints, it is possible for the copper and other metallic compounds in the paint to react with other metals on the boat, such as stainless steel, aluminum, or bronze, and cause galvanic corrosion. To prevent this from happening, it's important to take steps to isolate the metals from each other by using insulating materials, such as rubber or plastic washers, and by maintaining good electrical bonding and grounding between different metal components on the boat.
Can I use automotive grease if I don't have Mercury 2-4-c grease on hand?
While Mercury 2-4-C marine grease is specifically formulated for use in marine environments, it is possible to use automotive grease as a substitute if you don't have access to 2-4-C grease. However, there are some important factors to consider before doing so.
Automotive greases are not designed specifically for use in marine environments, and they may not provide the same level of protection against corrosion and water intrusion as 2-4-C grease. In addition, some automotive greases may not be compatible with the materials used in marine equipment, and they may cause damage or premature wear.
If you must use automotive grease as a substitute, it's important to choose a high-quality grease that is recommended for use in high-stress applications, such as wheel bearings and universal joints. You should also choose a grease that is formulated for use with the type of equipment you are working on, and that is compatible with the materials used in that equipment.
Keep in mind that using a substitute grease may void your warranty or cause other issues down the line, so it's always best to use the manufacturer-recommended grease whenever possible. If you are unsure about which type of grease to use, consult with a marine mechanic or the manufacturer of your equipment for guidance.
Can I use Yamalube grease in place of Mercury grease?
While Mercury 2-4-C marine grease is specifically formulated for use in Mercury outboards and other marine equipment, it is possible to use Yamalube grease as a substitute if you don't have access to Mercury grease.
Yamalube is a high-quality marine grease that is manufactured by Yamaha, and it is formulated to provide excellent protection against water intrusion, corrosion, and wear in marine environments. While it is not designed specifically for use in Mercury outboards, it is generally compatible with the materials used in most marine equipment and should work well as a substitute for Mercury grease.
I found corrosion in water jacket of 20 hp Mercury outboard - what repairs do I need to make?
If you have found corrosion in water jacket of 20 hp Mercury outboatd, it is recommended to take your outboard motor to a certified Mercury dealer or mechanic for inspection and repair. They can assess the extent of the damage and determine the necessary repairs. Depending on the severity of the corrosion, the repair may range from a simple cleaning and repainting to a complete overhaul of the engine. It is important to address this issue as soon as possible to prevent further damage and potential engine failure.
How long do corrosion inhibitors form a water resistant barrier on all metal surfaces?
The duration for which corrosion inhibitors form a water-resistant barrier on all metal surfaces depends on various factors, such as the type of inhibitor, the severity of the environment, and the application method. Generally, corrosion inhibitors can provide protection for weeks to several months, but may need to be reapplied periodically to maintain optimal protection. It is best to refer to the product instructions or consult with a professional for specific guidance on how long a particular corrosion inhibitor will last in your specific application.
Do "Mercury aluminium corrosion" and "Mercury aluminum corrosion" refer to the same thing?
Yes, "Mercury aluminium corrosion" and "Mercury aluminum corrosion" refer to the same thing. It is just a difference in spelling between American English, which uses "aluminum," and British English, which uses "aluminium."
