Mercury MerCruiser Oil Adaptor Seal - 26-42077
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The Mercury MerCruiser Quicksilver 26-42077 is a genuine Mercury Marine OEM seal used in select MerCruiser oil-system and engine adapter assemblies where the factory parts diagram calls for 42077 / 26-42077. This small molded seal is commonly associated with oil filter adaptor, oil cooler line, and bypass-related sealing locations on GM-based MerCruiser marine engines. It helps seal the adaptor interface and prevent engine oil leakage at the mounting surface.
Key Features
- Genuine Mercury Marine factory OEM seal.
- Mercury/MerCruiser part number: 26-42077.
- Manufacturer part number: 42077.
- Official part label: SEAL.
- GTIN/UPC: 745061146426.
- Listed shipping weight: 0.02 lb.
- Listed shipping dimensions: 1.25 in. L x 1.25 in. W x 0.25 in. H.
- Used where the Mercury/MerCruiser parts diagram calls for this seal in oil-system or adaptor-related assemblies.
Engine Compatibility
This seal is used across a wide range of Mercury/MerCruiser applications by serial number and diagram location. Common application groups include select:
- 7.4L MIE Gen V GM 454 V-8 applications
- 7.4L MIE Gen VI GM 454 V-8 applications
- 7.4L MIE MPI Gen V / Gen VI GM 454 V-8 applications
- 454 Mag / 454 Mag MPI Bravo Gen V and Gen VI applications
- 454 Mag MPI Horizon Gen VI applications
- 8.2L MIE Gen V GM 502 V-8 applications
- 8.2L MIE MPI Gen VI GM 502 V-8 applications
- Select 496 Mag applications where the diagram calls for this seal
- Additional MerCruiser engine groups where the parts diagram specifies 26-42077 / 42077
Use this part only where the factory Mercury/MerCruiser diagram calls for 26-42077.
Serial Number Fitment Notice
Confirm fitment by engine serial number, engine family, and exact oil-system diagram before ordering. Similar MerCruiser oil adaptor, cooler, and bypass assemblies can use different seals depending on Gen V/Gen VI configuration, block style, remote oil filter setup, and serial range.
When This Part Needs Replacement
Replace this seal if oil is seeping at the oil filter adaptor, remote filter adaptor, cooler-line adaptor, or related block-mounted oil-system housing. It should also be replaced any time the adaptor housing is removed, resealed, or serviced. A flattened, hardened, cut, swollen, or oil-soaked seal can allow oil leakage and should not be reused.
Installation Notes
Clean the sealing groove and mating surfaces before installation. Do not substitute a generic plumbing O-ring or hardware-store seal, as the correct profile and fit are important for oil-system sealing. Inspect the adaptor housing, fasteners, cooler lines, and related gaskets while the assembly is apart. Follow the MerCruiser service manual for the correct installation sequence and torque procedure for the specific engine.
Alternate/Superseded Part Numbers
- 26-42077 — Mercury/MerCruiser formatted part number
- 42077 — Manufacturer part number
Parts Desk Insight
This seal is inexpensive compared with the labour involved in accessing the oil adaptor area, so it is best replaced whenever the adaptor assembly is removed. Matching the seal by Mercury part number and diagram location is important because similar-looking oil seals may not compress or seat correctly in the adaptor groove.
Shipping: Ships same or next day for fast Canada wide shipping. ⚓
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
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If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
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Item must be in new, unused condition
Product must be in its original packaging
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Important:
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