Mercury Marine 27-73645 Gasket – Fits Mercury/Mariner 75-85 HP 4-Cylinder Outboard Motors
Mercury Marine 27-73645 Gasket – Fits Mercury/Mariner 75-85 HP 4-Cylinder Outboard Motors is backordered and will ship as soon as it is back in stock.
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Worry-free returns
You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Mercury Marine 27-73645 Gasket – Fits Mercury/Mariner 75-85 HP 4-Cy...
Product Details
This genuine Mercury Marine 27-73645 Gasket is designed for a precise fit on Mercury/Mariner 75, 80 (800), and 85 (850) HP 4-cylinder outboard motors. It ensures a reliable seal for optimal engine performance and longevity.
This part is a direct interchange for Mercury part numbers 27-73645 and 73645.
- Installation occurs at an engine-specific location.
- Engineered as a genuine Mercury Marine OEM component.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury | 27-73645 |
| Mercury | 73645 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury/Mariner engines, compatibility is often determined by serial number range rather than model year. Please verify your engine's serial number falls within the specified range.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | 75 (4 CYL.) | 75 | 4-Stroke | 6432901 & Up | 27-73645 | |
| Mercury | 75 (4 CYL.) | 75 | 4-Stroke | 7208573 & Up | 27-73645 | |
| Mercury | 75 (4 CYL.) | 75 | 4-Stroke | 9393856 & Up | 27-73645 | |
| Mercury | 80 | 80 | 4-Stroke | 4842729–5763340 | 27-73645 | |
| Mercury | 80 | 80 | 4-Stroke | 5763341–6432900 | 27-73645 | |
| Mercury | 80 | 80 | 4-Stroke | 7162528–7208572 | 27-73645 | |
| Mercury | 80 | 80 | 4-Stroke | 8066915 & Up | 27-73645 | |
| Mercury | 800 (4 CYL.), 80 (4 CYL.) | 80 | 4-Stroke | 5582562–6432900 | 27-73645 | |
| Mercury | 800 (4 CYL.), 80 (4 CYL.) | 80 | 4-Stroke | 7146213–7208572 | 27-73645 | |
| Mercury | 800 (4 CYL.), 80 (4 CYL.) | 80 | 4-Stroke | 8067015 & Up | 27-73645 | |
| Mercury | 800 (4 CYL.), 80 (4 CYL.) | 80 | 4-Stroke | 9256131–9393855 | 27-73645 | |
| Mercury | 800 (4 CYL.), 80 (4 CYL.) | 80 | 4-Stroke | 4831999–5582561 | 27-73645 | |
| Mercury | 800 (4 CYL.), 80 (4 CYL.) | 80 | 4-Stroke | 7110998–7146212 | 27-73645 | |
| Mercury | 800 (4 CYL.), 80 (4 CYL.) | 80 | 4-Stroke | 8050200–8067014 | 27-73645 | |
| Mercury | 800 (4 CYL.), 80 (4 CYL.) | 80 | 4-Stroke | 9177626–9256130 | 27-73645 | |
| Mercury | 85 | 85 | 4-Stroke | 4731898–4842728 | 27-73645 | |
| Mercury | 850 (4 CYL.) | 85 | 4-Stroke | 4366802–4831998 | 27-73645 | |
| Mercury | 850 (4 CYL.) | 85 | 4-Stroke | 7071373–7110997 | 27-73645 | |
| Mercury | 850 (4 CYL.) | 85 | 4-Stroke | 8043775–8050199 | 27-73645 | |
| Mercury | 850 (4 CYL.) | 85 | 4-Stroke | 9110014–9177625 | 27-73645 |
Technical Specs
- Product Type
- Gasket
- Installation
- Engine-specific location
- Dimensions
- 14.0" x 7.0" x 1.13"
- Weight
- 0.06 lbs (0.027 kg)
- Other Technical Attributes
- Genuine Mercury Marine OEM part
What’s in the Box
- 2 x Gasket (27-73645)
Installation Notes
- Ensure the engine is completely cool and disconnect the battery for safety.
- Locate and access the component requiring the new gasket.
- Carefully remove the old gasket, taking care not to gouge the mating surfaces.
- Thoroughly clean both surfaces of any old gasket material or sealant residue.
- Position the new gasket correctly onto the clean surface.
- Reassemble the components and tighten all fasteners to the manufacturer's specified torque sequence.
- After reassembly, reconnect the battery, start the engine, and inspect for any leaks.
Troubleshooting & FAQ
How do I confirm this gasket fits my specific engine?
The most reliable method is to check your engine's serial number against the ranges listed in the compatibility table. If your serial number falls within one of the listed ranges for your model, the part should fit.
What are the signs of a failed gasket?
Common symptoms include fluid leaks (oil, coolant), overheating, loss of compression, or poor engine performance. A visual inspection may also reveal cracks, brittleness, or deterioration in the old gasket.
Is this listing for one gasket or a set?
This package includes a set of two gaskets, as confirmed by part number 27-73645 documentation.
Do I need to use a sealant with this gasket?
While this is a genuine OEM gasket designed for a dry fit, always consult your engine's specific service manual. Some applications may recommend a light coating of a specific sealant, while others require a clean, dry installation.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
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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