The Mercury Oil Injection Pump Block-Off Kit, commonly searched as 43453T, 43453, 818304A1, and 8M0095447, is used when removing the factory oil injection system from many Mercury and Mariner 2.0L, 2.4L, and 2.5L V6 two-stroke outboards.
This conversion is popular with performance boat owners, racers, and experienced mechanics who prefer to premix two-stroke oil directly with gasoline instead of relying on the original crankshaft-driven oil pump.
On Mercury V6 two-stroke engines, the factory oil injection system uses a mechanical pump, oil tank, hoses, linkage, warning module, and drive components.
As these parts age, they can become a reliability concern, especially on older engines or high-RPM applications. Installing a proper block-off plug simplifies the lubrication system and gives the owner direct control over the fuel-to-oil ratio.
Choose Factory-Style Thermoplastic or Buckshot Racing Billet
Buckshot Racing #77 offers oil injection block-off options for different engine builds and customer preferences.
1) The factory-style thermoplastic block-off kit is a practical replacement for owners seeking an OEM-style solution similar to the original Mercury service configuration. It is lightweight, simple, and ideal for standard repairs, restorations, and recreational Mercury V6 premix conversions.
2) For performance builds, clean rigging projects, and Mercury Racing-style engine packages, the Buckshot Racing #77 billet aluminum oil injection block-off kit offers an upgraded appearance and added durability.
The billet version is a popular choice for custom Black Max, XR6, XRi, Pro Max, 2.5L performance, and Mercury Racing-style V6 outboards where strength, finish, and long-term reliability matter.
Both options are designed to seal the original oil pump mounting location after the factory oil injection pump is removed. The right choice depends on whether the customer prefers a factory-style service part or a more premium billet upgrade.
Mercury and Mariner Fitment
This kit is commonly used on many Mercury 135 HP, 150 HP, 175 HP, 200 HP, and 225 HP V6 two-stroke outboards, including Black Max, XR2, XR4, XR6, Magnum, XRi, EFI, carbureted V6, Pro Max 200, Pro Max 225, and other 2.0 Liter, 2.4 Liter, and 2.5 Liter Mercury and Mariner engines equipped with the factory oil injection pump.
It is often installed on bass boats, lake boats, performance hulls, and older Mercury Racing-style builds where the owner wants a simpler premix fuel system. Because Mercury used several oil injection layouts over many years, always confirm fitment by engine serial number, original oil pump design, and factory parts diagram.
OEM Part Numbers and Cross References
Common search and cross-reference numbers include 43453T, 43453, 818304A1, 8M0095447, 32509, 815698, 41429A2, 12726, and 193856.
The typical factory-style kit includes the block-off plug 43453, sealing O-ring 25-11379, and two mounting screws commonly referenced as 10-41506. These parts seal the original oil pump mounting location after the pump assembly is removed.
Why Convert to Premix?
The main reason for installing a Mercury V6 oil injection block-off kit is reliability. A premix system removes dependence on the oil pump, tank, hoses, linkage, drive gear, and warning hardware. With premix, every gallon of gasoline already contains oil, so lubrication no longer depends on the pump delivering oil correctly.
This conversion is especially common on older Mercury V6 outboards where original oil injection parts are aged, brittle, contaminated, or no longer trusted. It is also popular in performance use where owners want a consistent oil ratio and fewer moving parts.
While any drag reduction from removing the oil pump drive is small, the simplified system can reduce failure points and make future troubleshooting easier.
Installation Overview
Installation starts by removing the factory oil pump, linkage, and related oil injection parts from the pump mounting area. The surface should be cleaned carefully so the new block-off plug seats properly. The O-ring should be lightly lubricated, and many mechanics apply a thin layer of suitable marine-grade sealant only where needed to help prevent leakage.
The block-off plug is then aligned with the original oil pump opening and secured with the included screws. It should fit cleanly and should not be forced. Tighten the screws evenly without over-torquing the aluminum crankcase.
Before running the engine, the fuel system must be converted to premix and clearly marked so straight gasoline is never accidentally added. Use the correct fuel-oil mixture for the specific Mercury V6 engine and operating style.
Buckshot Racing #77 Tech Tip
Once oil injection is removed, the engine has no automatic oil supply. Every tank of fuel must be premixed correctly before startup. Buckshot Racing #77 recommends labeling the fuel fill, cowling, or dash with a clear PREMIX ONLY warning to help prevent accidental engine damage.
Also, remove or secure old oil lines, warning-module wiring, remote oil tank parts, and unused oil injection components. Leaving disconnected hoses or loose wiring under the cowling can cause confusion during future service.
Final Thoughts
The Mercury 43453T Oil Injection Block-Off Kit is a simple but important upgrade for many Mercury and Mariner 2.0L, 2.4L, and 2.5L V6 two-stroke outboards.
Whether you are maintaining a 150 Black Max, XR4, XR6, 175 EFI, 200 XRi, 200 Pro Max, or 225 Pro Max, removing the factory oil injection system and switching to premix can simplify the engine and improve confidence in older or performance-focused applications.
For standard repairs, choose the factory-style thermoplastic oil injection block-off kit. For performance builds and custom Mercury outboards, choose the Buckshot Racing #77 billet aluminum block-off kit. Either way, treat the conversion as a complete lubrication-system change, not just a plug installation.
For technical questions or to confirm compatibility, contact Mike Hill at mike@buckshotracing77.com or call (714) 697-1716.