The part number 1144-6691A 1 (often listed as 1144-6691A1 or with related base 1144-6690) is a Mercury Quicksilver OEM lower end cap assembly (or lower crankshaft/end cap) used in the crankcase/cylinder block assembly of certain 3-cylinder 2-stroke Mercury outboard engines.

It is specifically associated with 50 HP and 60 HP (3-cylinder) models, as well as some related 65 HP or 650 variants in older nomenclature (though primarily documented for 50-60 HP ranges).

Compatible Horsepower

• Primarily 50 HP (inline 3-cylinder 2-stroke)
• Also 60 HP (inline 3-cylinder 2-stroke)
• Occasionally cross-referenced in parts diagrams for 65 HP or 650 (3-cylinder) models from the late 1970s to early 1990s era.

These are carbureted 2-stroke engines, not the later EFI or 4-stroke versions.

Years/Models

This part appears in parts catalogs and breakdowns for Mercury 3-cylinder engines from roughly the late 1980s through the early/mid-1990s (and possibly into the early 2000s for some carryover models). Specific examples from parts listings and diagrams include:

• Mercury 50 HP (3 cyl.) models with serial ranges like 0A110315 and up (early 1990s+)
• Mercury/Mariner 50-60 HP (3 cyl.) in various international/Belgium-built versions
• Older references tie it to models around serial prefixes in the 4xxx, 5xxx, 6xxx, up to 0A ranges (late 1970s–1990s production for these 3-cyl designs)
• It shows up in cylinder block/crankcase diagrams for engines like the 650 (3 cyl.) from serials around 9020074–9135824 (late 1980s–early 1990s)

Mercury transitioned these 3-cylinder 50/60 HP designs over time, with some parts like this end cap used across multiple serial year ranges until superseded or phased out (it's now often listed as "NLA" or no longer available new from Mercury).