Gasket Powerhead Engine Base – Mercury/Mercruiser (Replaces 27-796501, 27-72496, 27-37725, 27-79650, 18-0103)
Gasket Powerhead Engine Base – Mercury/Mercruiser (Replaces 27-796501, 27-72496, 27-37725, 27-79650, 18-0103) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
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.).
You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).
If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.
Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Gasket Powerhead Engine Base – Mercury/Mercruiser (Replaces 27-7965...
Product Details
This is a high-quality aftermarket Gasket Powerhead Engine Base – Mercury/Mercruiser (Replaces 27-796501, 27-72496, 27-37725, 27-79650, 18-0103), engineered to seal the powerhead to the engine block. It is designed for a precise fit on Mercury and Mariner 30 Jet HP, 40 HP, and 45 HP inline 4-cylinder engines manufactured from 1989 through current models.
It serves as a direct replacement for several OEM and aftermarket part numbers, including Mercury Marine 27-796501, Quicksilver 27-796501, 27-72496, 27-37725, 27-79650, and Sierra 18-0103, ensuring broad compatibility.
- Installs at the powerhead engine base.
- Engineered to meet or exceed OEM specifications for a reliable seal.
- Maintains compression and prevents water or oil leaks between major engine components.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Notes |
|---|---|---|
| Mercury / Mariner | 27-796501 | Current OEM Reference |
| Quicksilver | 27-796501 | OEM Equivalent |
| Mercury Marine | 27-79650 | Superseded Part Number |
| Mercury Marine | 27-72496 | Superseded Part Number |
| Mercury Marine | 27-37725 | Superseded Part Number |
| Sierra | 18-0103 | Aftermarket Interchange |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This gasket is designed for specific Mercury and Mariner 4-cylinder outboards. Check your engine model and serial number against the chart to ensure a correct fit.
| Brand | Model | Rated HP | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|
| Mercury/Mariner | 30 Jet | 30 | 1989–Current | 27-796501 | s/n 9570790 and up; s/n 0C159200 Thru 0G589999 |
| Mercury/Mariner | 40 | 40 | 1989–Current | 27-796501 | 4-cyl, s/n 9570790 and up; s/n 0C159200 and up |
| Mercury/Mariner | 45 | 45 | 1989–Current | 27-796501 | 4-cyl, s/n 0A719281 & Up; s/n 0B110789 & Up; s/n 9466692 & Up |
Technical Specs
- Product Type
- Gasket
- Installation
- Powerhead Engine Base
- Housing Color
- Grey
- Dimensions
- 25.5 x 16.5 x 0.5 in
- Weight
- 0.05 lbs
What’s in the Box
- 1 x Gasket (27-79650-1)
Installation Notes
- Disconnect the battery and ensure the engine is completely cool before starting.
- Drain engine coolant and oil to prevent spillage during disassembly.
- Remove the engine cover and any components that block access to the powerhead.
- Carefully label and disconnect all fuel lines, electrical connectors, and mechanical linkages from the powerhead.
- Systematically unbolt and remove the powerhead from the midsection. This may require a lifting hoist.
- Remove the old powerhead base gasket. Thoroughly clean both mating surfaces, ensuring they are free of any old gasket material, sealant, oil, and corrosion.
- Position the new gasket on the engine base, carefully aligning it with all bolt holes and passages.
- Lower the powerhead back onto the gasket, taking care not to shift its position.
- Install and tighten the powerhead bolts in the sequence and to the torque values specified in your engine’s service manual.
- Reconnect all previously removed fuel lines, electrical wiring, and linkages.
- Refill the engine with the correct type and amount of oil and coolant.
- After reassembly, prime the fuel system, start the engine, and carefully inspect for any signs of leaks.
Troubleshooting & FAQ
How do I know if my powerhead base gasket is failing?
Common symptoms of a failed powerhead gasket include water in the cylinders, oil or water leaks between the powerhead and the drive shaft housing, engine overheating, poor performance, or a noticeable loss of compression.
Is any sealant required with this gasket?
Generally, this gasket is designed for a dry installation and does not require any additional sealant. However, always consult your engine’s official service manual, as it may specify the use of a sealant in certain areas.
What is the most common cause of powerhead gasket failure?
Engine overheating is the leading cause of powerhead gasket failure. Other factors include improper installation, re-using stretched bolts, incorrect bolt torque, or imperfections on the mating surfaces of the engine block and powerhead.
Can I reuse my existing powerhead bolts?
It is strongly recommended to use new powerhead bolts during installation. Old bolts can stretch and may not provide the correct, even clamping force required for a durable seal, which can lead to premature gasket failure.
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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