Mercury MerCruiser Engine Mount Jam Nut 3/4-16 49252
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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 Current Mercury dealer references show 49252 superseded to 859126, and current OEM-style engine-mounting diagrams identify the replacement as a 3/4-16 jam nut used with the mount base, tab washer, and lockwasher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Alternate/Superseded Part Numbers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. ⚓
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
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For return authorization, please contact our support team before shipping anything back.