Mercury Quicksilver 16756A6 Crankshaft Center Main Bearing Kit — V6 Outboard & Jet Drive

Mercury Quicksilver 16756A6 — Crankshaft Center Main Bearing Kit, V6 Outboard & Jet Drive

Overview

The Mercury Quicksilver 16756A6 is a genuine OEM crankshaft center main bearing kit for selected Mercury V6 outboard and jet-drive powerheads. Mercury parts diagrams place this kit at the center main bearing positions within the crankshaft, piston, and connecting-rod assembly — where it supports the crankshaft and maintains correct running clearance within the powerhead. In six-cylinder crankshaft assemblies, up to two kits may be required; confirm quantity by diagram before ordering.

Important: Main bearing kits are not interchangeable by diameter alone. Bearing width, race design, crankshaft position, and running clearance all vary by application. Always confirm the correct part number using the exact Mercury model, serial number, and powerhead diagram before ordering.

Supersession

• Current part number: 16756A6 (service format: 31-16756A6)
• Supersedes: 16756A1 (31-16756A1)
• Supersedes: 16756A3 (31-16756A3)
• If your service records or parts diagram show 16756A1 or 16756A3, 16756A6 is the correct current OEM replacement.

Compatible Applications

• Mercury 175XR2 Jet Drive — center main bearing positions (confirm serial range)
• Mercury 200 DFI Jet Drive — center main bearing positions (confirm serial range)
• Mercury 200 DFI M2 Jet Drive — center main bearing positions (confirm serial range)
• Mercury 210 Carb Jet Drive — center main bearing positions (confirm serial range)
• Mercury 210 Carb M2 Jet Drive — center main bearing positions (confirm serial range)
• Mercury 240 EFI Jet Drive — center main bearing positions (confirm serial range)
• Mercury 240 EFI M2 Jet Drive — center main bearing positions (confirm serial range)
• Mercury V-115 DFI 2.5L outboard — center main bearing positions (confirm serial range)
• Mercury V-135 outboard — center main bearing positions (confirm serial range)
• Mercury Magnum III V6 outboard — center main bearing positions (confirm serial range)
• Other compatible Mercury V6 outboard crankshaft assemblies (confirm model and serial range)
• Always confirm by exact model, serial number, and crankshaft diagram — production ranges and required quantities can vary within the same engine family

When to Replace

• During crankshaft or powerhead overhaul — bearing inspection is standard practice whenever the crankshaft is removed
• Bearing shows scoring, pitting, surface roughness, or overheating damage (bluing)
• Crankshaft-to-bearing running clearance is out of specification
• Metal contamination found inside the powerhead during teardown
• Lubrication failure has occurred — even briefly running without adequate oil causes bearing damage that is not always visible on the surface
• Excessive crankshaft journal wear is found that requires re-bearing or crankshaft replacement

Installation Notes

• Confirm the correct quantity of bearing kits required for the specific crankshaft assembly before disassembly — up to two kits may be needed in a six-cylinder powerhead
• Inspect crankshaft journals, bearing seating surfaces, sealing rings, and lubrication passages before reassembly — a worn or damaged journal will destroy new bearings quickly
• Mercury diagrams place 16756A6 adjacent to the center-main crankshaft sealing and carrier components — inspect the full crankshaft assembly area during rebuild work
• Follow the Mercury service manual for the exact engine and serial range for bearing installation procedure, clearance specifications, and torque values
• Cleanliness is critical — any debris or contamination in the bearing area during assembly will cause premature failure

Technical FAQ

• Why can’t I use a bearing that looks the same diameter? Center main bearings are matched to the crankshaft journal dimensions, bearing width, and running-clearance specification for that specific powerhead. A bearing that fits physically but has the wrong clearance will cause crankshaft noise, reduced oil film, and early failure.
• How many kits do I need for a full crankshaft overhaul? In six-cylinder V6 powerheads, up to two 16756A6 kits may be required for the center main positions. Check the Mercury parts diagram for your exact engine and serial number to confirm the total quantity before ordering.
• Can I replace just the worn bearing without inspecting the crankshaft journal? No. If a main bearing has failed, the crankshaft journal must be measured for wear and damage before installing new bearings. A scored or out-of-spec journal will damage new bearings immediately and require another teardown.
• What causes center main bearing failure in Mercury V6 outboards? The most common causes are lubrication failure (oil injection system fault, oil starvation, or running on straight gasoline), internal contamination from cooling water intrusion, and detonation damage. Correct two-stroke oil ratio and a functioning oil injection system are critical to bearing longevity.
• Is this kit used in both conventional outboard and jet-drive versions of the same engine? Yes — Mercury parts diagrams show 16756A6 in both conventional V6 outboard powerheads and jet-drive powerhead configurations that share the same basic engine block. The center main bearing position is common to both. Confirm by your exact model and serial number.

Parts Desk Insights

Best Use Case: This kit is the right call during a proper Mercury V6 crankshaft or powerhead rebuild where the parts diagram specifically calls for 16756A6 at the center main bearing positions. It’s most commonly ordered during overhauls following lubrication failure, water intrusion, or when excessive crankshaft clearance is found during inspection. Because up to two kits can be needed in a six-cylinder assembly, always check the diagram for quantity before ordering — it’s worth confirming once rather than ordering again mid-teardown.

Common Issues: The most frequent mistake is ordering a single kit when the diagram requires two for a complete center main bearing service on a six-cylinder powerhead. The second common issue is installing new bearings on a crankshaft with worn or scored journals — new bearings on a worn journal fail quickly and require a second teardown. If the crankshaft has any visible scoring, measure the journals before ordering bearings.

Related Products

• Mercury Quicksilver 2-Stroke Outboard Oil Seal — 26-41953
• Mercury High Performance 2-Stroke Oil — 8M0078011