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Sierra
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Tune Up Kit Thunderbolt HEI V6 | Sierra 18-5274
Keep your Mercruiser V6 running at peak performance with this essential tune-up kit. Featuring a premium cap and rotor assembly, it's engineered specifically for Thunderbolt distributors to ensure reliable ignition and smooth operation. A must-have maintenance item for any serious boater looking to avoid costly downtime.
Maintaining your marine engine is essential for a smooth boating season. Therefore, investing in a high-quality ignition service is a smart choice. The Tune Up Kit Thunderbolt HEI V6 | Sierra 18-5274 offers a professional-grade solution for your vessel. Since this kit is specifically engineered for Mercury Thunderbolt HEI V-6 engines, it ensures a perfect fit every time.
This comprehensive kit includes the vital parts needed to refresh your ignition system. For instance, it features the 18-5396 distributor cap and the 18-5432 rotor assembly. Additionally, a durable gasket is included to create a secure, weather-tight seal. Because marine environments are harsh, these components use premium materials to resist corrosion. Consequently, your engine will start more reliably even in damp conditions.
Sierra is a trusted name in the boating industry for over fifty years. Furthermore, their parts are designed to meet or exceed original equipment manufacturer (OEM) specifications. This means you get the same performance as factory parts but often at a better value. Meanwhile, the high-conductivity terminals within the cap ensure a strong spark. As a result, you will notice improved fuel efficiency and smoother idling during your trips.
Many boaters prefer to handle their own maintenance to save time and money. Fortunately, the Sierra 18-5274 kit is designed for a straightforward installation process. Since the parts are direct replacements, you do not need to perform any complex modifications. However, you should always double-check your engine serial number before starting the job. Once installed, the new components will provide peace of mind for the entire season.
Finding the right part can sometimes be confusing for boat owners. Nevertheless, the 18-5274 kit is highly versatile across several major brands. For example, it is interchangeable with GLM 71790 and Mallory 9-29317. It also replaces Mercury Marine part numbers 815407Q5 and 815407T6. Because it covers such a wide range of V6 applications, it is a staple for marine technicians.
Regular maintenance prevents costly breakdowns when you are far from the shore. In addition, a fresh distributor cap and rotor prevent engine misfires and power loss. If your boat has been sitting for the winter, moisture may have affected your old ignition parts. Therefore, replacing them with a new Sierra kit is the best way to prepare for spring. Ultimately, this small investment protects the longevity of your Mercruiser engine.

Would have been 5 stars but, I did not receive a promotional sticker with my $2000 drive unit. Just kidding, everything was great!
Great company to work with!
Ordered a Piranha Propellers Complete A-Series 4 Blade Propeller from Macomb Marine Parts and even though we’re international, it arrived in just over a week — fast and reliable service. The propeller itself is a real lifesaver. We had the same model before, and after hitting a rock that damaged two blades, we were able to swap them right on the water and make it back to the marina without issue — something you simply can’t do with a regular aluminum prop. For peace of mind we decided to buy a complete new set (hub and blades) since an impact like that could cause hidden damage, but the system really proved its worth.
3 in. Exhaust Elbow | Pleasurecraft R029001
Excellent part.
I couldn’t find a Piranha propeller dealer near me in Canada but found Macomb Marine Parts who could deliver to me. The order process was smooth and I was even contacted via email for clarification regarding blade shape and they were very helpful in choosing the best shape for my purposes.
I can’t comment on the prop’s performance yet as we haven’t had the boat in the water yet.
Perfect replacement. thank you
Perfect replacement
Perfect match to the original Chris Craft blue. Competitive price and delivery was quick
Great Product, easy to install, work well
Obtaining magnesium anodes to install on the OMC Cobra (SX-C) sterndrive, for fresh water use. Received the anode within a week of ordering the part, which is not going to be installed until Spring.
Black Liquid Electrical Tape - 4 oz. | Star Brite 084104B
As described
Very Happy!! Just what I needed!!
Outdrive spent 4 months docked in salt water with no visible rust on the stainless steel braided hoses
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Would have been 5 stars but, I did not receive a promotional sticker with my $2000 drive unit. Just kidding, everything was great!
Great company to work with!
Ordered a Piranha Propellers Complete A-Series 4 Blade Propeller from Macomb Marine Parts and even though we’re international, it arrived in just over a week — fast and reliable service. The propeller itself is a real lifesaver. We had the same model before, and after hitting a rock that damaged two blades, we were able to swap them right on the water and make it back to the marina without issue — something you simply can’t do with a regular aluminum prop. For peace of mind we decided to buy a complete new set (hub and blades) since an impact like that could cause hidden damage, but the system really proved its worth.