Gasket 27-33956 – Fits Mercury/Mercruiser, Volvo Penta, OMC (Replaces 27-33956, 3853342)
Gasket 27-33956 – Fits Mercury/Mercruiser, Volvo Penta, OMC (Replaces 27-33956, 3853342) 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 27-33956 – Fits Mercury/Mercruiser, Volvo Penta, OMC (Replac...
Product Details
This replacement Gasket 27-33956 is designed for the water pump assembly on various Mercury/Mercruiser, Volvo Penta, and OMC stern drive and inboard engines. Specifically, it fits many 4 and 6-cylinder Mercruiser models and serves as a direct cross-reference for Volvo Penta and OMC models that specify part number 3853342.
It provides a direct replacement for Mercury/Mercruiser 27-33956/27-879150138/FI5000200/FI5000219, OMC 3853342, Volvo Penta 3853342, Sierra 18-0327, GLM 31350, and Mallory 9-60067.
- Requires no modifications for a clean installation.
- Made from a durable paper/fiber composite for a reliable seal.
- Engineered for use in marine water pump sealing applications.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury/Mercruiser | 27-33956 |
| Mercury/Mercruiser | 27-879150138 |
| Mercury/Mercruiser | FI5000200 |
| Mercury/Mercruiser | FI5000219 |
| OMC | 3853342 |
| Volvo Penta | 3853342 |
| Sierra | 18-0327 |
| GLM | 31350 |
| Mallory | 9-60067 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
Fits various 4- and 6-cylinder stern drive and inboard engines.
Compatible with various models using interchange part number 3853342.
Fits various models using interchange part number 3853342.
| Brand | Model | Rated HP | Stroke | OEM Part No. | Notes |
|---|---|---|---|---|---|
| Mercury/Mercruiser | 4 & 6 Cylinder Stern Drive | Various | 4-Stroke | 27-33956/27-879150138 | Water pump gasket |
| Volvo Penta | Various Models | Various | 4-Stroke | 3853342 | Water pump gasket |
| OMC | Various Models | Various | 4-Stroke | 3853342 | Water pump gasket |
Technical Specs
- Product Type
- Water Pump Gasket
- Installation
- Direct replacement, no modifications required
- Material
- Paper/Fiber Composite
- Color
- Brown/Tan
- Dimensions
- 6.0" x 7.13" x 0.13"
- Application
- Marine water pump sealing
What’s in the Box
- 1 x Gasket (27-33956/3853342)
Installation Notes
- Ensure the engine is off, cool, and disconnected from the power source. Close the water intake seacock.
- Drain the cooling system sufficiently to prevent spillage when the pump is opened.
- Carefully remove the bolts securing the water pump cover or housing.
- Gently pry off the cover. Remove the old gasket and any remaining sealant or debris.
- Clean both mating surfaces meticulously. Ensure they are smooth, clean, and dry before proceeding.
- Position the new gasket correctly over the alignment pins or bolt holes. Do not use sealant unless specified by the engine manufacturer for your model.
- Reinstall the water pump cover, ensuring it is seated evenly.
- Tighten the bolts in a crisscross pattern to the manufacturer's recommended torque specifications.
- Re-open the seacock, refill the cooling system, and reconnect the power. Start the engine and carefully inspect for any leaks around the pump housing.
Troubleshooting & FAQ
How do I know if this gasket fits my specific engine model?
The best method is to match your existing part number to one of the numbers listed in our Part Number Matrix. This gasket fits a wide range of Mercury, Volvo Penta, and OMC engines, but visual confirmation and part number matching are critical.
What are the signs of a failing water pump gasket?
Common signs include visible water leaks or drips from the water pump housing, engine overheating, or a low coolant warning. You may also see rust or corrosion around the pump seam, indicating a slow leak.
Do I need to use sealant with this gasket?
Most modern gaskets, including this one, are designed to be installed dry on clean, flat surfaces. Using sealant can sometimes cause the gasket to slip or extrude. However, always follow the specific service manual recommendations for your engine model, as some older designs or pitted surfaces may require a thin layer of a non-hardening sealant.
How often should a water pump gasket be replaced?
It is recommended to replace the water pump gasket whenever the water pump impeller is serviced or the pump housing is removed for any reason. This prevents leaks from developing due to a compressed or aged gasket.
What is the difference between OEM and aftermarket parts?
This listing is for an aftermarket replacement, not an original equipment manufacturer (OEM) part. It is built to the same specifications using comparable materials and is manufactured in an ISO 9002 certified facility. All parts are batch-inspected for quality and consistency.
What are your shipping speed and cost?
We ship worldwide quickly, with a typical transit time of 5–15 days for most regions. Standard shipping is free. Expedited shipping options and exact costs will be displayed at checkout if available for your location.
What is your warranty and return policy?
This part is covered by a 1-year warranty against manufacturing defects under normal marine use. If you encounter an issue, please contact our support team with your order details. Returns are accepted within our standard window for unused parts in their original condition. See our policy page or reach out for instructions.
Safety & Important Info
- Verify images and specifications against 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 quality control.
Payment & Security
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