Boating Spark Plug DIY

Checking your plugs in your spring maintenance routine.

Getting the boat ready for springtime commissioning often includes checking and/or replacing sparkplugs. DIY types who own inboards or stern-drives are familiar with hard to reach parts, especially in twin engine applications. Sometimes we would like nothing better than to string up the person responsible for making things difficult to work on because of obstructions, poor design, and awkward access for servicing.

SnapOn S9724RHS Low-Profile Spark Plug Socket

For those in the boat and motor business, encounters in tight quarters, rusted parts, and hot engine compartments are everyday occurrences. Any tool that makes a job easier and quicker is something to be appreciated. Snap-on Tools, famous for their professional grade mechanics tools, makes a “shorty” sparkplug socket that is a lifesaver on those V-6 and V-8 engines with 5/8” hex sparkplugs hidden under water-cooled exhaust manifolds.

Limited access to the plugs previously required ingenious methods of modifying sockets or wrenches to fit over the hard-to-reach sparkplugs. The Snap-on #S9724RHS "shorty" socket, only 1-1/16" long, easily slides over the ceramic portion and the tapered hex grips the metal sparkplug shell securely. A 5/8" open-end, box, or ratcheting wrench on the low-profile socket can then loosen or tighten the sparkplug effortlessly. This sparkplug socket is just the thing for those Ford V-8 stern-drives with their knuckle-busting limited-access exhaust manifolds.

Not only can the Snap-on socket be used on boats, but it is invaluable on cars with custom exhaust headers, late model Harley-Davidsons, and for other engines that use 5/8" ( 16mm ) hex sparkplugs in confined spaces. Priced at $31.25, it is not inexpensive but pays for itself with fewer broken sparkplugs, less blood lost, and in reduced aggravation when working in a tight areas.

You can order one through a Snap-on Tool Representative, online at, or by calling 877-762-7664. If you have a few friends with similar engines, split the cost of the sparkplug socket and share. That can minimize your investment for a special tool that you may only need once or twice a year.