Mercury Quicksilver OEM Stainless Steel Washer 4002317 | 12-4002317 | 8.90 x 17.0 x 1.9 mm | Gear Housing Driveshaft Jet Cowl

Mercury Quicksilver OEM Stainless Steel Washer — Part 4002317

• Part Number: 4002317
• Full Catalog Number: 12-4002317
• Brand: Mercury Marine / Quicksilver (Genuine OEM)
• Official Product Type: Hardware & Fasteners — Stainless Steel Flat Washer
• Material: Stainless steel
• Inside Diameter: 8.90 mm / 0.350 in.
• Outside Diameter: 17.0 mm / 0.669 in.
• Thickness: 1.9 mm / 0.075 in.
• Primary Verified Uses: Gear housing screw washers, driveshaft housing screw washers, jet unit assembly, starter assemblies, and top cowl mounting hardware
• Replaces: 805792 (earlier washer superseded by 4002317 in selected MerCruiser applications)
• Weight: approx. 0.005 kg

Multi-application washer — match by part number and diagram position: 4002317 is used in many unrelated Mercury outboard assemblies, from small-outboard gear housing and driveshaft housing fasteners to V12 top cowl hardware. The required quantity and mating fastener vary by assembly. Always confirm from the Mercury parts diagram for the specific engine model, serial number, and assembly location before ordering.

What It Is

The 4002317 / 12-4002317 is the genuine OEM stainless steel flat washer sized at 8.90 mm ID x 17.0 mm OD x 1.9 mm thick used across a wide range of Mercury and Mariner outboard assemblies. Mercury specifies this washer in gear housing screw stacks, driveshaft housing fasteners, jet unit assemblies, manual and electric starter mounting points, and top cowl latch hardware on engines ranging from small two-stroke singles to the 600 HP V12 FourStroke. It supersedes earlier Mercury washer 805792 in selected MerCruiser applications. Because 4002317 appears in so many different assemblies, the part number and diagram position are more reliable guides than the engine family or horsepower alone.

Compatible Applications

Confirm the correct quantity and mating hardware from the Mercury parts diagram for the specific engine model and serial number before ordering. Quantity per assembly varies significantly by application.

Driveshaft Housing — Screw Washer

• Mercury 25 HP two-cylinder outboards — driveshaft housing screw washer — 6 washers per assembly (typical)
• Mercury 25 Sea Pro — driveshaft housing screw washer — 6 washers per assembly (typical)
• Mercury Super 15 two-cylinder outboards — driveshaft housing screw washer — 6 washers per assembly (typical)

Gear Housing — Screw Washer

• Mercury 18 HP two-stroke outboards — gear housing screw washer — 4 washers per assembly (typical) — used with M8 x 25 mm screw 4000353

Jet Unit Assembly

• Mercury 60 HP EFI FourStroke Jet — jet unit assembly — 4 washers per assembly (typical)

Starter Assembly

• Mercury 9.9 HP FourStroke — manual starter assembly
• Selected Mercury outboards — starter motor mounting diagrams

Top Cowl Hardware

• Mercury 600 HP 7.6L V12 FourStroke — top cowl latching hardware — 2 washers per assembly — Mercury identifies dimensions as 8.90 x 17.0 x 1.9 mm stainless steel in this diagram

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

Related Hardware

Verified mating hardware for 4002317 by assembly. These are sold separately:

• 4000353 — M8 x 25 mm gear housing screw (paired with 4002317 in gear housing assemblies)
• 1993870 — M8 x 70 mm driveshaft housing screw (paired with 4002317 in driveshaft housing assemblies)
• 4000354 — Screw used with 4002317 in selected mounting assemblies
• 8M0178135 — M8 x 30 mm screw (used with 4002317 in V12 top cowl hardware)
• 805792 — Earlier washer superseded by 4002317 in selected MerCruiser applications

Part Numbers

• 4002317 — Current Mercury / Quicksilver OEM part number
• 12-4002317 — Full Mercury / Quicksilver catalog number
• 805792 — Earlier Mercury washer superseded by 4002317 in selected MerCruiser assembly applications

When to Replace

Replace the washer when:

• It is bent, cupped, or distorted from overtightening or impact
• Corrosion or surface pitting is present on the washer face or bore
• The mounting hole has elongated from movement or fretting
• The washer was lost during disassembly and cannot be recovered
• The mating bolt or screw has damaged the washer face during removal
• Gear housing, driveshaft housing, jet unit, or bracket hardware is being renewed during service

Service Interval

No fixed interval — inspect on condition. 4002317 is accessed during gear housing, driveshaft housing, jet unit, or starter assembly service. Because the washer is an inexpensive component relative to the fastener stacks it supports, replacing it whenever the assembly hardware is being renewed during a major gear housing or driveshaft service is a sound practice. Stainless steel washers in saltwater environments can develop surface corrosion or galling at the thread interface over time, particularly in gear housing applications where they are exposed to moisture.

Installation Notes

• Confirm 4002317 is the correct washer and quantity from the Mercury parts diagram for the specific engine model, serial number, and assembly position before ordering — quantity varies from 2 to 6 depending on the assembly
• Confirm the correct mating screw (4000353, 1993870, 4000354, or 8M0178135) from the parts diagram for the specific assembly
• Clean the mating surface and fastener bore before installing the replacement washer
• Inspect the mating screw or stud for thread condition and corrosion while the assembly is apart
• Use the torque specification for the exact screw and assembly from the applicable Mercury service manual — do not apply a single universal torque value across all applications
• Do not assume all M8 hardware positions in the same engine use the same washer — confirm 4002317 is called out in the specific diagram position

Technical FAQ

Q: How many 4002317 washers do I need?
It depends entirely on the assembly. Verified quantities include: 6 per driveshaft housing assembly (25 HP, 25 Sea Pro, Super 15), 4 per gear housing assembly (18 HP), 4 per jet unit assembly (60 HP EFI FourStroke Jet), and 2 per top cowl assembly (V12 600 HP). Confirm the correct quantity from the parts diagram for the specific engine and assembly before ordering.

Q: Is 4002317 a standard M8 flat washer I can get at a hardware store?
The dimensions (8.90 mm ID x 17.0 mm OD x 1.9 mm thick, stainless steel) are specific to Mercury OEM specifications. While a hardware-grade M8 flat washer may have similar dimensions, the OEM washer ensures correct material grade, finish, and dimensional tolerances for the marine environment. For gear housing and driveshaft housing applications in particular, using the OEM washer is the correct approach.

Q: What did 4002317 replace?
4002317 supersedes earlier Mercury washer 805792 in selected MerCruiser assembly applications. If your parts diagram shows 805792 or the Mercury parts system redirects 805792 to 4002317, order 4002317.

Q: Can I use 4002317 in a MerCruiser sterndrive assembly?
4002317 supersedes 805792 in selected MerCruiser applications where 805784 and 805782 screws are used, so yes, it is used in some MerCruiser assemblies. Confirm from the MerCruiser parts diagram that 4002317 is specified for the exact assembly and position being serviced.

Parts Desk Insights

The most useful thing to know about 4002317 is its exact size — 8.90 mm ID x 17.0 mm OD x 1.9 mm thick, stainless steel. Mercury uses it across a remarkably wide range of assemblies from small two-stroke outboards to the V12 600 HP FourStroke, which means the part number and diagram position matter far more than the engine horsepower. The most common ordering issue is customers not knowing the quantity they need — it varies from 2 to 6 depending on the assembly, so confirming the quantity from the diagram before placing the order prevents a second order. Customers searching for 805792 should be pointed to 4002317 as the current OEM replacement.