Mercury MerCruiser OEM Stainless Steel Screw M8 x 35 mm 40011151 | Shift Plate Thermostat Housing Outboard Mount

Mercury MerCruiser OEM Stainless Steel Screw M8 × 35 mm — Part 40011151

• Part Number: 40011151
• Full Catalog Number: 10-40011151
• Brand: Mercury Marine / MerCruiser (Genuine OEM)
• Official Product Type: Hardware & Fasteners — Stainless Steel Screw
• Thread Size: M8
• Length: 35 mm (approx. 1.38 in.)
• Material: Stainless steel
• System: Multi-application — used in MerCruiser shift plate, thermostat housing, and Mercury outboard mounting assemblies
• Weight: approx. 0.02 kg per screw

Multi-application fastener — match by part number and diagram position: 40011151 is used in several different Mercury and MerCruiser assemblies. Required quantity, head style, and surrounding hardware vary by assembly and location. An M8 × 35 mm dimension alone is not sufficient to confirm correct fitment — always confirm against the serial-number-specific Mercury or MerCruiser parts diagram for your assembly.

What It Is

The 40011151 is a genuine OEM stainless-steel M8 × 35 mm screw used across multiple Mercury Marine and MerCruiser assemblies. Verified applications include MerCruiser shift-plate hardware, thermostat housing assemblies, and selected Mercury outboard lower-mount and yoke configurations. Because this fastener appears in multiple assembly contexts with varying required quantities, the correct approach is always to confirm the part number from the serial-number-specific diagram for your exact assembly before ordering.

Verified Assembly Applications

Confirm the required part number and quantity from the serial-number-specific Mercury or MerCruiser diagram for your assembly before ordering.

MerCruiser Shift Plate / Shift Actuator Assembly

• One 40011151 screw shown in applicable shift-plate assembly diagrams
• Used alongside shift actuator 879194T46, shift plate bracket 865481 / 8629091 (application-dependent), shift cable retainer 864616, shift arm lever 8M2018371, shift arm spacer 863132, and stud 864361

MerCruiser Thermostat Housing Assembly

• Two 40011151 screws shown in applicable thermostat housing diagrams
• Used alongside thermostat housing assembly 864398T1, thermostat housing gasket 530451, 77°C / 170°F thermostat 864493, and thermostat housing cover 807075A1

Mercury Outboard Lower-Mount / Yoke Assembly

• Four 40011151 screws shown in applicable outboard lower-mount and bottom-yoke diagrams

Not sure this is the correct fastener? Send us your Mercury or MerCruiser serial number and assembly location before ordering.

Related Fasteners

• 40011155 — M8 × 55 mm stainless-steel screw used nearby in certain shift-plate assemblies — not interchangeable with 40011151 based on length alone

Part Numbers

• 40011151 — Mercury Marine OEM part number
• 10-40011151 — Full Mercury catalog number

No separate superseding Mercury part number is confirmed in current parts references. Order 40011151 / 10-40011151.

When to Replace

Replace the screw when:

• Threads are damaged, stretched, or corroded
• The fastener head is rounded or damaged from previous removal
• The screw has seized during removal and cannot be reused
• Significant corrosion is present on the screw body or threads
• The original fastener is missing
• The applicable Mercury service procedure specifies fastener replacement during assembly service

Inspect the mating female threads before installing a new screw, especially if the previous fastener was seized or cross-threaded. Damaged threads in the casting must be addressed before the new fastener is installed.

Service Interval

No fixed replacement interval — replace on condition. Inspect threaded fasteners in cooling-system and shift-linkage assemblies during each annual service or whenever the assembly is opened. Stainless-steel fasteners into aluminium castings (thermostat housing) should be inspected for galvanic corrosion at each service and replaced proactively if any binding or corrosion is found on removal — a seized stainless screw can damage the casting thread on extraction if left too long.

Installation Notes

• Confirm the Mercury or MerCruiser parts diagram for your assembly and serial number calls for 40011151 at the specific location being serviced — verify both part number and required quantity
• Verify the 35 mm length: do not substitute 40011155 (M8 × 55 mm) or another M8 fastener of a different length, as incorrect fastener length can result in incomplete thread engagement or contact with internal components
• Inspect female threads in the mating component for damage or corrosion before installation
• Confirm related washers, spacers, or brackets are installed in the correct order before threading the fastener
• Do not assume the same torque specification applies at every location where 40011151 is used — torque values differ between shift-plate, thermostat-housing, and outboard-mount assemblies
• Use thread treatment (locking compound, anti-seize) only where specified by the Mercury service procedure for the exact assembly — requirements vary by location

Technical FAQ

Q: Can I use any M8 × 35 mm stainless screw instead of 40011151?
Not recommended. While the thread size and length are M8 × 35 mm, Mercury specifies 40011151 for these assemblies based on head style, strength grade, and material grade. Using a non-OEM substitute may not meet the torque requirements or corrosion resistance needed for the specific marine assembly location. Always use the OEM part where specified by the diagram.

Q: How many 40011151 screws do I need?
It depends on the assembly. The shift-plate diagram typically uses one, the thermostat housing uses two, and outboard lower-mount assemblies use four. Confirm the required quantity from the parts diagram for your specific assembly and serial number.

Q: What is the difference between 40011151 and 40011155?
40011155 is an M8 × 55 mm stainless screw — the same thread diameter but 20 mm longer. It is used nearby in certain shift-plate assemblies. The two screws are not interchangeable based on length. Confirm the correct part number from the diagram for each fastener position.

Parts Desk Insights

The most important point about 40011151 is that it is a multi-application Mercury fastener, so the 35 mm length alone does not confirm fitment. The safest approach is always to confirm the OEM number from the serial-number-specific schematic for the exact assembly location. The most common issue in practice is ordering the wrong quantity — the number required varies from one to four depending on whether the assembly is a shift plate, thermostat housing, or outboard mount. When replacing thermostat housing screws specifically, inspect the aluminium threads in the housing carefully on removal: stainless screws in aluminium are prone to galvanic locking over time, and the housing thread is the damage-prone component if the screw has to be extracted forcefully.