Gasket, Water Jacket Cover – Fits Mercury Outboards 75-85HP (Replaces Mercury Marine 27-73665)
Gasket, Water Jacket Cover – Fits Mercury Outboards 75-85HP (Replaces Mercury Marine 27-73665) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Gasket, Water Jacket Cover – Fits Mercury Outboards 75-85HP (Replac...
Product Details
This Gasket, Water Jacket Cover is an essential replacement component designed for Mercury Outboards, including 75HP (4-Cyl), 80HP (4-Cyl, 800), and 85HP (4-Cyl, 850) models. It ensures a proper seal to prevent coolant leaks and maintain engine temperature.
This part is a direct replacement for Mercury Marine 27-73665.
- Creates a secure seal for the water jacket cover
- Engineered to match OEM dimensions for a precise fit
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury Marine | 27-73665 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This gasket is compatible with a wide range of Mercury engines. Please verify your model and serial number range.
Fits various Mariner outboard models that utilize the OEM part number 27-73665.
| Brand | Model | Rated HP | Years | OEM Part No. |
|---|---|---|---|---|
| Mercury | 75 (4 CYL.) | 75 | 6432901 & Up | 27-73665 |
| Mercury | 75 (4 CYL.) | 75 | 7208573 & Up | 27-73665 |
| Mercury | 75 (4 CYL.) | 75 | 9393856 & Up | 27-73665 |
| Mercury | 80 | 80 | 4842729 THRU 5763340 | 27-73665 |
| Mercury | 80 | 80 | 5763341 THRU 6432900 | 27-73665 |
| Mercury | 80 | 80 | 7162528 THRU 7208572 | 27-73665 |
| Mercury | 80 | 80 | 8066915 AND UP | 27-73665 |
| Mercury | 800 (4 CYL.) | 80 | 5582562 THRU 6432900 | 27-73665 |
| Mercury | 800 (4 CYL.) | 80 | 7146213 THRU 7208572 | 27-73665 |
| Mercury | 800 (4 CYL.) | 80 | 8067015 & Up | 27-73665 |
| Mercury | 800 (4 CYL.) | 80 | 9256131 THRU 9393855 | 27-73665 |
| Mercury | 800 (4 CYL.) | 80 | 4831999 THRU 5582561 | 27-73665 |
| Mercury | 800 (4 CYL.) | 80 | 7110998 THRU 7146212 | 27-73665 |
| Mercury | 800 (4 CYL.) | 80 | 8050200 THRU 8067014 | 27-73665 |
| Mercury | 800 (4 CYL.) | 80 | 9177626 THRU 9256130 | 27-73665 |
| Mercury | 85 | 85 | 4731898 THRU 4842728 | 27-73665 |
| Mercury | 850 (4 CYL.) | 85 | 4366802 THRU 4831998 | 27-73665 |
| Mercury | 850 (4 CYL.) | 85 | 7071373 THRU 7110997 | 27-73665 |
| Mercury | 850 (4 CYL.) | 85 | 8043775 THRU 8050199 | 27-73665 |
| Mercury | 850 (4 CYL.) | 85 | 9110014 THRU 9177625 | 27-73665 |
| Mariner | 75 (4 CYL.) | 75 | 27-73665 | |
| Mariner | 80 | 80 | 27-73665 | |
| Mariner | 85 | 85 | 27-73665 |
Technical Specs
- Product Type
- Gasket, Water Jacket Cover
- Other Technical Attributes
- Water Jacket Cover Gasket
- Dimensions
- Length: 1.13 in, Width: 13.0 in, Height: 10.0 in
- Weight
- 0.027 kg (0.06 lb)
What’s in the Box
- 1 x Gasket (27-73665)
Installation Notes
- Disconnect the battery and ensure the engine is completely cool before starting.
- Drain the cooling system as required to access the water jacket cover.
- Carefully unbolt and remove the water jacket cover.
- Remove the old gasket and meticulously clean both the cover and engine block mating surfaces. Ensure no residue remains.
- Position the new gasket correctly onto the engine block, aligning it with the bolt holes.
- Reinstall the water jacket cover and tighten the bolts to the manufacturer's specified torque in the correct sequence.
- Refill the cooling system with the appropriate coolant.
- Reconnect the battery, start the engine, and carefully inspect for any leaks around the cover.
Troubleshooting & FAQ
How do I know if my water jacket cover gasket is failing?
Common signs include visible coolant leaks around the water jacket cover, engine overheating, or a milky appearance in the engine oil, which could indicate a coolant breach. A visual inspection for cracks or degradation on the exposed parts of the gasket can also signal a need for replacement.
Is this gasket compatible with both Mercury and Mariner 80HP models?
Yes, this gasket is designed to fit specific 80HP models from both Mercury and Mariner that use the OEM part number 27-73665. Please refer to the detailed compatibility table and verify your engine's serial number range to ensure a correct fit.
What is the most important step during installation?
The most critical step is ensuring both mating surfaces—the engine block and the water jacket cover—are perfectly clean and free of any old gasket material or debris before placing the new gasket. An uneven or dirty surface will prevent a proper seal and lead to leaks.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, it is batch-inspected for consistency and reliability.
Shipping speed & cost
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns
Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
Payment & Security
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