Sterndrive Engineering (SEI) offers a complete line of trim cylinders and other hydraulic parts that are compatible with MerCruiser’s® cylinders for the Alpha One® and Gen II stern drives and outdrives.

SEI’s stern drive trim cylinders undergo an extensive testing process. Each trim cylinder is tested before shipment to ensure that there are no leaks, that it has full range of motion, and can withstand pressure. The design and operation of a MerCruiser® trim cylinder is actually rather complex. The cylinder must be able to expand outward very quickly in the event of impact on the drive. This is achieved with a pressure relief valve built into the piston of the trim cylinder. The relief valve consists of three ball bearings sitting on individual holes with one spring exerting equal pressure on all three balls. The balls must seal on the holes or the piston will leak hydraulic fluid from the high pressure side of the trim cylinder to the low pressure side. The piston also has a smaller reverse direction one-way relief valve that allows the trim cylinder to reset after such an incident. These functions are 100% tested in every trim cylinder produced by SEI that fits/replaces MerCruiser® trim cylinders.

The MerCruiser® outdrive is very common in 17 to 25 ft runabout boats. In fact, MerCruiser’s® market share through most of the '70s, '80s, and '90s was estimated by experts to be over 80 percent. SEI trim cylinders are designed as an economical replacement for MerCruiser’s® trim cylinders. In our opinion, it makes no sense for the owner of an older boat worth only several thousand dollars to spend top dollar for new MerCruiser® cylinders. Many of SEI's customers are actively seeking for economical solutions for older boats.

SEI has been in the outdrive business since 2003. The company was founded by Greg Pickren. Mr. Pickren also is the owner and founder of the company Short Block Technologies, Inc. (SBT), which is the largest supplier of Persoanl Water Craft engines in the world. Justin Webb is the General Manager of SEI and was previously employed by Konrad Marine and GLM. Mr. Webb is an expert on MerCruiser® cylinders with many years of experience with MerCruiser® hydraulic parts.

Sterndrive Engineering is the largest supplier of replacement stern drives in the world. SEI’s stern drives come with an industry leading three-year, fault-free warranty and are assembled at its factory in Clearwater, Florida. Thank you for your interest in the company and its transom repair products.