Mercury MerCruiser Engine Mount Jam Nut 3/4-16 49252

Mercury MerCruiser 49252 is a genuine OEM nut used in engine mounting assemblies on a wide range of MerCruiser gasoline and diesel applications. Current Mercury dealer references show 49252 superseded to 859126, and current OEM-style engine-mounting diagrams identify the replacement as a 3/4-16 jam nut used with the mount base, tab washer, and lockwasher hardware stack.

Key Features

• Genuine Mercury Marine OEM part number 49252.
• Current replacement part number is 859126.
• Current engine-mounting diagrams identify the replacement as a 3/4-16 jam nut.
• Used in the engine mounting hardware stack with the mount base, tab washer, and lockwasher.
• Current dealer shipping specs for 49252 are approximately 0.06 lb, 1.25 in. x 1.25 in. x 1.00 in.

Engine Compatibility

Current Mercury dealer references connect 49252 to a broad range of MerCruiser applications, including 200/230/260/350 MAG/5.0L/5.7L/454 MAG/502 MAG/7.4L/7.4LX gasoline packages, plus diesel coverage such as 7.3L Bravo & MIE diesel and D7.3L D-Tronic. Current OEM-style diagrams also place the superseding 859126 in engine mounting layouts for applications such as 5.7L EFI/TBI, 7.4LX Bravo, 454 EFI / 502 EFI Gen V, and 496 MAG families.

Serial Number Fitment Notice

Verify fitment by exact engine serial number and the correct engine mounting parts diagram before ordering. This nut appears across multiple MerCruiser engine families, so serial-based confirmation is the safest way to match the correct mounting hardware and replacement number.

When This Part Needs Replacement

Replace this nut when the original is damaged, rounded, corroded, distorted, or removed during engine-mount service and no longer suitable for reuse. Because current diagrams place it in the engine-mount hardware stack, correct fit and thread condition matter for secure mount adjustment and retention. This is a practical service inference based on its documented engine-mounting role.

Installation Notes

Install this part only after confirming the correct MerCruiser engine-mounting diagram for the engine being serviced. Current diagrams show the superseding 859126 used with the base assembly 814263A1, tab washer 12657, and lockwasher 68102, so it should be matched to the exact mount arrangement during reassembly.

Alternate/Superseded Part Numbers

Current Mercury references show 859126 as the superseding replacement for 49252.

Parts Desk Insight

With engine-mount hardware like this, the important match is the mounting diagram and thread size, not just the word nut. Checking the serial-number-based engine-mount breakdown first is the easiest way to avoid getting the wrong hardware for the mount stack.

Shipping: Ships same or next day for fast Canada wide shipping.