GASKET, POWERHEAD TO EXHAUST EXTENSION PLATE – Fits Mercury/Mariner 4 & 6 Cylinder Inline (Replaces 27-692381, 27-60479, 27-64173, 27-66101, 27-69238)
GASKET, POWERHEAD TO EXHAUST EXTENSION PLATE – Fits Mercury/Mariner 4 & 6 Cylinder Inline (Replaces 27-692381, 27-60479, 27-64173, 27-66101, 27-69238) 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
GASKET, POWERHEAD TO EXHAUST EXTENSION PLATE – Fits Mercury/Mariner...
Product Details
This is an aftermarket Gasket, Powerhead to Exhaust Extension Plate, designed for a wide range of Mercury and Mariner 4 & 6 Cylinder Inline engines, including models from 75 HP to 150 HP manufactured between 1973 and 1988. It serves as a crucial seal between the powerhead and the exhaust extension plate.
This part is a direct replacement for Mercury-Mercruiser part number 27-692381 and interchanges with WSM 510-27, WSM 18-2835, and Offshore Marine 121-14-381.
- Installs between the powerhead and exhaust extension plate.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket suppliers.
| Brand | Part Number | Notes |
|---|---|---|
| Mercury-Mercruiser | 27-692381 | Primary OEM reference. Also replaces 27-69238, 27-60479, 27-64173, and 27-66101. |
| WSM | 510-27 | Aftermarket Interchange |
| WSM | 18-2835 | Aftermarket Interchange |
| Offshore Marine | 121-14-381 | Aftermarket Interchange |
Engine & Model Compatibility
Confirm your engine model and year in the table below.
For Mercury and Mariner outboards, please verify your engine's specifications against this list to ensure proper fitment.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | 75 HP | 75 | 4-Cylinder | 1975–Up | 27-692381 | |
| Mercury | 80 HP | 80 | 4-Cylinder | 1978–1983 | 27-692381 | |
| Mercury | 85 HP | 85 | 4-Cylinder | 1973–1985 | 27-692381 | |
| Mercury | 90 HP | 90 | 6-Cylinder | 1975–1988 | 27-692381 | |
| Mercury | 115 HP | 115 | 6-Cylinder | 1975–1988 | 27-692381 | |
| Mercury | 140 HP | 140 | 6-Cylinder | 1978–1981 | 27-692381 | |
| Mercury | 150 HP | 150 | 6-Cylinder | 1973–1978 | 27-692381 |
Technical Specs
- Product Type
- Gasket, Powerhead Base
- Installation
- Powerhead to Exhaust Extension Plate
- Dimensions
- Length: 0.13 in | Width: 10.0 in | Height: 13.0 in
- Weight
- 0.009 kg (0.02 lbs)
What’s in the Box
- 1 x Gasket (Replaces 27-692381)
Installation Notes
- Ensure the engine is off, cool, and the battery is disconnected before starting.
- Remove the engine cowling to access the powerhead assembly.
- Carefully unbolt and remove the powerhead from the exhaust extension plate.
- Remove the old gasket and thoroughly clean any remaining gasket material from both mating surfaces. Ensure they are smooth and dry.
- Position the new gasket correctly, aligning it with the bolt holes.
- Re-install the powerhead and tighten the bolts in the sequence and to the torque values specified in your engine’s service manual.
- Reassemble all other components, reconnect the battery, and check for any exhaust or water leaks after starting the engine.
Troubleshooting & FAQ
How can I confirm this gasket fits my specific engine?
The best way is to match your engine's model, horsepower, and year to our compatibility table. You can also cross-reference your existing part number with our Part Number Matrix to confirm it is a listed equivalent.
What are the signs of a failing powerhead base gasket?
Common symptoms include engine overheating, loss of power or compression, water found in the cylinders (milky oil), or visible water and exhaust leaks from the seam between the powerhead and the lower unit.
Should I use sealant or adhesive with this gasket?
Most gaskets of this type are designed for dry installation. Applying sealants can sometimes interfere with proper sealing. Always refer to your engine’s official service manual for the manufacturer-recommended procedure.
How often should this gasket be replaced?
This gasket should be replaced any time the powerhead is removed for service or if a leak is diagnosed. It is not typically replaced as part of a routine maintenance schedule.
The compatibility table lists "Looper" engines. What does that mean?
A "Looper" or loop-charged engine is a type of two-stroke engine design. While our compatibility list may include models with this design, it is always most important to confirm fitment using your engine's specific model, year, and OEM part number.
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.
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