Mercury Quicksilver OEM M6 Stainless Steel Nut 400212 | 11-400212 | Throttle Cable Bracket Hardware

Mercury Quicksilver OEM M6 Stainless Steel Nut — Part 400212

• Part Number: 400212
• Full Catalog Number: 11-400212
• Brand: Mercury Marine / Quicksilver (Genuine OEM)
• Official Product Type: Hardware & Fasteners — M6 Stainless Steel Nut
• Thread Size: M6
• Material: Stainless steel
• Primary Verified Uses: Throttle cable attachment, throttle control linkage, steering handle / swivel bracket assemblies, and fuel tank / mounting bracket hardware
• GTIN / UPC: 745061078215
• Weight: approx. 0.01 kg

Match by part number and diagram position — not by thread size alone: Mercury uses several different M6 nuts in closely related outboard assemblies, including 401386 and 401366 in some of the same engine families. 400212 / 11-400212 is the specific OEM nut for the assembly positions where the Mercury parts diagram calls for this number. Do not substitute a different M6 nut based on thread size alone — locking style, material grade, and finish can differ.

What It Is

The 400212 / 11-400212 is the genuine OEM M6 stainless steel nut used across multiple Mercury and Mariner outboard assembly locations. Verified diagram applications include throttle cable attachment hardware, throttle control linkage assemblies, steering handle and swivel bracket assemblies, and fuel tank and mounting bracket hardware. On selected 15 HP two-stroke steering handle assemblies, Mercury specifically identifies 400212 as the M6 stainless steel throttle cable nut. On selected 6 HP FourStroke fuel tank assemblies, it serves as the M6 stainless mounting nut in the tank and bracket hardware. Mercury diagrams also show two 400212 nuts paired with M6 x 55 mm screws (40124) in certain throttle control and linkage assemblies.

Compatible Applications

400212 is a multi-location M6 nut used across several Mercury and Mariner outboard assembly positions. Confirm the exact parts diagram for the specific engine model, serial number, and assembly location before ordering — the same engine may use 400212 alongside other M6 nuts (401386, 401366) in adjacent positions.

• Mercury 15 HP two-stroke — steering handle assembly — throttle cable nut
• Mercury 6 HP FourStroke — fuel tank and mounting bracket assembly — M6 mounting nut
• Selected Mercury and Mariner outboard throttle cable attachment hardware — where the diagram specifies 400212
• Selected Mercury and Mariner throttle control linkage assemblies — paired with M6 x 55 mm screw 40124 (two nuts per assembly, typical)
• Selected Mercury and Mariner steering handle and swivel bracket assemblies
• Additional Mercury outboard locations where the parts diagram specifically calls for 400212

Not sure it fits? Send us your Mercury or Mariner outboard serial number and the assembly being serviced before ordering.

Related Hardware

Depending on the assembly, 400212 may be used with the following components. These are sold separately:

• 40124 — M6 x 55 mm screw (paired with two 400212 nuts in throttle control/linkage assemblies)
• 42942 — Cap
• 821113 — Bushing
• 42927 — Insert
• 8M0215006 — Swivel bushing
• 401386 — Alternate M6 nut used elsewhere in the same assemblies (confirm diagram position)
• 401366 — Alternate M6 stainless nut on selected configurations (confirm diagram position)

Part Numbers

• 400212 — Current Mercury Marine OEM part number
• 11-400212 — Full Mercury / Quicksilver catalog number

No superseding Mercury part number is confirmed in current OEM references for 400212.

When to Replace

Replace the nut when:

• Threads are stripped, damaged, or cross-threaded
• Corrosion is present on the nut body or threads
• The nut has rounded flats and can no longer be driven with a wrench
• The nut has seized to the mating screw or stud
• The original fastener is missing from the assembly
• Throttle, bracket, or fuel tank service requires replacement of the original hardware

When replacing 400212, inspect the mating M6 screw or stud at the same time — especially if the original nut was seized or cross-threaded, as the mating thread may also be damaged.

Service Interval

No fixed interval — inspect on condition. In saltwater and high-humidity environments, inspect all throttle cable, linkage, and bracket fasteners during annual service for corrosion, thread condition, and security. Stainless steel fasteners in marine environments can still gall or corrode at the thread interface over time, particularly where dissimilar metals are in contact. Replacing any fastener that shows thread damage or corrosion during service is the correct approach rather than reusing questionable hardware.

Installation Notes

• Confirm 400212 is the nut specified at the exact diagram position being serviced — not all M6 nuts in the same Mercury outboard assembly are the same part number
• Do not substitute 401386 or 401366 for 400212 without confirming from the parts diagram — locking style, profile, or material finish may differ
• In throttle control linkage assemblies where 400212 is paired with screw 40124, two nuts are typically used — confirm the quantity from the Mercury parts diagram before ordering
• Inspect the mating screw or stud for thread condition and corrosion before installing the replacement nut
• Apply anti-seize or corrosion inhibitor to the threads if specified by the applicable Mercury service manual for the assembly location
• Torque to the specification in the applicable Mercury outboard service manual for the specific assembly — do not assume a generic M6 torque value applies to all locations

Technical FAQ

Q: Is 400212 a standard M6 nut I can replace with any M6 nut?
No. While 400212 is an M6 thread, Mercury uses several different M6 nuts in closely related outboard assemblies, including 401386 and 401366. These may differ in locking style, profile, or finish and are not always interchangeable at the same diagram position. Order by the exact OEM part number shown in the Mercury parts diagram for the assembly being serviced.

Q: How many 400212 nuts do I need?
It depends on the assembly. In throttle control and linkage assemblies where 400212 is paired with M6 x 55 mm screw 40124, Mercury diagrams typically show two nuts per assembly. In single-point bracket or cable applications, one nut may be all that is required. Confirm the quantity from the parts diagram for the specific assembly before ordering.

Q: Can 400212 be used with any M6 screw?
400212 is a standard M6 thread and will engage any M6-threaded screw. However, the specific screw paired with 400212 in verified diagram applications is typically 40124 (M6 x 55 mm) in throttle linkage assemblies. Always confirm the correct screw and nut pairing from the Mercury parts diagram for the assembly being serviced rather than mixing fastener components.

Parts Desk Insights

The most important detail with 400212 is that it is not a generic M6 nut — Mercury uses several different M6 nuts in the same outboard families, and matching to the exact diagram position is the correct approach. The most common ordering confusion is customers asking for “the M6 nut” without specifying the assembly, which can result in ordering 401386 or 401366 when 400212 is the correct part, or vice versa. Throttle cable and linkage hardware on older Mercury outboards is also a common corrosion point — when a customer is doing throttle or bracket service, suggesting they replace all hardware in the assembly rather than just the damaged nut is worth mentioning.