Thermostat Gasket – Fits Mercury/Mariner 40-60HP (Replaces 27-8128671)
Thermostat Gasket – Fits Mercury/Mariner 40-60HP (Replaces 27-8128671) 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
Thermostat Gasket – Fits Mercury/Mariner 40-60HP (Replaces 27-8128671)
Product Details
This is a high-quality aftermarket Thermostat Gasket – Fits Mercury/Mariner 40-60HP (Replaces 27-8128671), designed for a precise seal on various 2-stroke and 4-stroke engines. It covers models from 1986 through the present, including many Jet models, ensuring reliable cooling system performance.
It serves as a direct replacement for Mercury 27-812867-1/27-8128671, GLM 35011, Sierra 18-2729, and Quicksilver 27-8128671.
- Engineered for direct-fit installation.
- Creates a durable seal for the thermostat housing.
- Resists degradation from engine heat and coolant.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Notes |
|---|---|---|
| Mercury / Quicksilver | 27-8128671 | Supersedes 27-812867-1 |
| GLM | 35011 | |
| Sierra | 18-2729 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
Compatibility includes various Mercury and Mariner 2-stroke models. Please verify your specific model and serial number range from the list below.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | 40 JET | 40 | 2-Stroke | 1998–2004 | 27-8128671 | 0P094500 THRU 0P325499, 0T178500 THRU 0T979999 |
| Mercury | 40 JET | 40 | 2-Stroke | 2004+ | 27-8128671 | 0P325500 & Up, 0T980000 & Up |
| Mercury | 45 JET | 45 | 2-Stroke | 1996–1998 | 27-8128671 | 9683055 THRU 9885344 |
| Mercury | 45 JET | 45 | 2-Stroke | 1998–2001 | 27-8128671 | 0D000750 THRU 0G290584 |
| Mercury | 45 JET | 45 | 2-Stroke | 2001–2003 | 27-8128671 | 0P017000 THRU 0P094499 |
| Mercury | 45 JET | 45 | 2-Stroke | 2001+ | 27-8128671 | 0G760300 THRU 0T129554 |
| Mercury | 50 (3 CYL.) | 50 | 2-Stroke | 1996–1998 | 27-8128671 | 9683055 THRU 9885344 |
| Mercury | 50 (3 CYL.) | 50 | 2-Stroke | 1998–2001 | 27-8128671 | 0D000750 THRU 0G290584 |
| Mercury | 55 (3 CYL.) | 55 | 2-Stroke | 1997–1998 | 27-8128671 | 9741042 THRU 9885344 |
| Mercury | 55 (3 CYL.) | 55 | 2-Stroke | 1998–2001 | 27-8128671 | 0D000750 THRU 0G290584 |
| Mercury | 55 (3 CYL.) | 55 | 2-Stroke | 2001+ | 27-8128671 | 0P325500 & Up, 0T980000 & Up |
| Mercury | 55 (3 CYL.) | 55 | 2-Stroke | 2001–2003 | 27-8128671 | 0G760300 THRU 0T979999, 0P017000 THRU 0P325499 |
| Mercury | 60 (3 CYL.) | 60 | 2-Stroke | 1996–1998 | 27-8128671 | 9683055 THRU 9885344 |
| Mercury | 60 (3 CYL.) | 60 | 2-Stroke | 1998–2001 | 27-8128671 | 0D000750 THRU 0G290584 |
| Mercury | 60 (3 CYL.) | 60 | 2-Stroke | 2001+ | 27-8128671 | 0P325500 & Up, 0T980000 & Up |
| Mercury | 60 (3 CYL.) | 60 | 2-Stroke | 2001–2003 | 27-8128671 | 0G760300 THRU 0T979999, 0P017000 THRU 0P325499 |
| Mercury | 60 (3 CYL.) BIGFOOT | 60 | 2-Stroke | 2001–2003 | 27-8128671 | 0G760300 THRU 0T979999, 0P017000 THRU 0P325499 |
The gasket is also used in various systems across multiple engine models, including Electrical, Exhaust/Cooling, Fuel/Oil, and Trim/Tilt/Lift systems from 1986 to present.
Technical Specs
- Product Type
- Thermostat Cover Gasket
- Installation
- Direct Replacement
- Housing Material
- Gasket Material (Paper/Composite)
- Dimensions (L x W x H)
- 10.5 x 11.0 x 0.1 inches
- Weight
- 0.02 lbs (0.009 kg)
- Warranty
- Manufacturer dependent
- GTIN
- 745061306998
What’s in the Box
- 1 x GASKET (27-8128671)
Installation Notes
- Ensure the engine is completely cool and disconnect the negative battery terminal for safety.
- Locate the thermostat housing on the engine block. You may need to drain a small amount of coolant.
- Unscrew the bolts holding the thermostat housing cover in place.
- Carefully remove the cover and the old gasket. Take care not to drop any parts into the engine.
- Thoroughly clean both the housing cover and the engine block mating surfaces. All old gasket material and sealant must be removed for a proper seal.
- Place the new gasket into position on the clean housing surface.
- Reinstall the thermostat cover and tighten the bolts in a crossing pattern to the manufacturer's specified torque. Do not overtighten.
- If coolant was drained, refill the system. Reconnect the battery.
- Start the engine, let it warm up, and carefully inspect the housing for any signs of leaks.
Troubleshooting & FAQ
How do I know if my thermostat gasket is failing?
Common signs include visible coolant leaks around the thermostat housing, engine overheating or running unusually hot, and finding the old gasket is cracked, brittle, or compressed upon inspection.
Is this gasket compatible with my specific engine serial number?
This gasket fits a wide range of Mercury and Mariner models. Please consult the "Engine & Model Compatibility" table above and cross-reference your engine's model and serial number range to ensure an exact match.
Do I need to use a sealant with this gasket?
Typically, this type of gasket is designed to be installed dry on clean, flat surfaces. However, always consult your engine's official service manual for specific recommendations regarding the use of supplemental sealants.
What is the difference between this and the original OEM part?
This aftermarket gasket is designed to meet or exceed OEM specifications for fit, form, and function. It provides a reliable seal and durable performance as a cost-effective alternative to the original manufacturer's part.
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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