Gasket – Fits Mercury/Mercruiser V135–V200, 110/140/150 Jet, 200XS, 225X (Replaces 27-78690002, 27-78690, 27-67624, 78690, 67624, 657, 18-0936, 540-28)
Gasket – Fits Mercury/Mercruiser V135–V200, 110/140/150 Jet, 200XS, 225X (Replaces 27-78690002, 27-78690, 27-67624, 78690, 67624, 657, 18-0936, 540-28) 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
Gasket – Fits Mercury/Mercruiser V135–V200, 110/140/150 Jet, 200XS,...
Product Details
This high-quality aftermarket Gasket – Fits Mercury/Mercruiser V135–V200, 110/140/150 Jet, 200XS, 225X is designed for the relief valve cover and plate on a wide range of Mercury, Mercruiser, and Mariner V6 outboard engines. It ensures a precise seal for optimal engine performance and reliability.
It serves as a direct replacement for Mercury/Mercruiser part numbers 27-78690002, 27-78690, 27-67624, and Sierra 18-0936, among other equivalents.
- Installs on the relief valve cover and plate.
- Engineered to meet or exceed original equipment specifications.
- Constructed from durable materials for a long-lasting seal.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury / Mercruiser | 27-78690002 |
| Mercury / Mariner | 27-78690 |
| Mercury / Mariner | 27-67624 |
| Generic | 78690 |
| Generic | 67624 |
| Generic | 657 |
| Sierra | 18-0936 |
| Pro Marine | 540-28 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury and Mercruiser outboards, verify your model and serial number range to ensure an exact match.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | V-135 | 135 | 2-Stroke | 0G960500–0T178499 | 27-78690002 | |
| Mercury | V-135 DFI (2.5L) | 135 | 2-Stroke | 0T801000–1B226999 | 27-78690002 | |
| Mercury | V-135 DFI (2.5L) | 135 | 2-Stroke | 1B227000–1B417701 | 27-78690002 | |
| Mercury | V-135 DFI (2.5L) | 135 | 2-Stroke | 1B417702 & Up | 27-78690002 | |
| Mercury | V-140 (International) | 140 | 2-Stroke | 0T178500–1B226999 | 27-78690002 | |
| Mercury | V-150 | 150 | 2-Stroke | 0G960500–1B226999 | 27-78690002 | |
| Mercury | V-150 DFI (2.5L) | 150 | 2-Stroke | 0T801000–1B226999 | 27-78690002 | |
| Mercury | V-150 DFI (2.5L) | 150 | 2-Stroke | 1B227000–1B417701 | 27-78690002 | |
| Mercury | V-150 DFI (2.5L) | 150 | 2-Stroke | 1B417702 & Up | 27-78690002 | |
| Mercury | V-150 EFI (2.5L) | 150 | 2-Stroke | 0T801000–1B226999 | 27-78690002 | |
| Mercury | V-150 EFI (2.5L) | 150 | 2-Stroke | 1B227000 & Up | 27-78690002 | |
| Mercury | V-175 DFI (2.5L) | 175 | 2-Stroke | 0T801000–1B226999 | 27-78690002 | |
| Mercury | V-175 DFI (2.5L) | 175 | 2-Stroke | 1B227000–1B417701 | 27-78690002 | |
| Mercury | V-175 DFI (2.5L) | 175 | 2-Stroke | 1B417702 & Up | 27-78690002 | |
| Mercury | V-200 | 200 | 2-Stroke | 0G960500–1B226999 | 27-78690002 | |
| Mercury | V-200 EFI (2.5L) | 200 | 2-Stroke | 0T801000–1B226999 | 27-78690002 | |
| Mercury | V-200 EFI (2.5L) | 200 | 2-Stroke | 1B227000 & Up | 27-78690002 | |
| Mercury | XR-6 | N/A | 2-Stroke | 0G960500–1B226999 | 27-78690002 | |
| Mercury | 200XS DFI (2.5L) | 200 | 2-Stroke | 0T818181–1E000796 | 27-78690002 | |
| Mercury | 200XS DFI (2.5L) | 200 | 2-Stroke | 1E000797–1E002110 | 27-78690002 | |
| Mercury | 200XS DFI (2.5L) ROS | 200 | 2-Stroke | 1E050852 & Up | 27-78690002 | |
| Mercury | 200XS SST | 200 | 2-Stroke | 1E050629 & Up | 27-78690002 | |
| Mercury | 225X EFI PROMAX | 225 | 2-Stroke | 0T430254–0T819605 | 27-78690002 | |
| Mercury | 110 Jet (2.5L) | 110 | 2-Stroke | 1B690542 & Up | 27-78690002 | |
| Mercury | 140 Jet | 140 | 2-Stroke | 0G960500–0T178499 | 27-78690002 | |
| Mercury | 150 Pro XS (2.5L) | 150 | 2-Stroke | 1B690542 & Up | 27-78690002 | |
| Mercury | 175 PROXS (2.5L) | 175 | 2-Stroke | 1B516339 & Up | 27-78690002 | |
| Mercury | Magnum III | N/A | 2-Stroke | 0G960500–1B226999 | 27-78690002 | |
| Mariner | V6 2.0L | N/A | 2-Stroke | 27-78690002 | Also replaces 27-78690, 27-67624, 78690, 67624, 657, 18-0936, 540-28 | |
| Mariner | V6 2.4L | N/A | 2-Stroke | 27-78690002 | Also replaces 27-78690, 27-67624, 78690, 67624, 657, 18-0936, 540-28 | |
| Mariner | V6 2.5L | N/A | 2-Stroke | 27-78690002 | Also replaces 27-78690, 27-67624, 78690, 67624, 657, 18-0936, 540-28 |
Technical Specs
- Product Type
- Gasket
- Installation
- Relief Valve Cover and Plate
- Dimensions
- Length: 0.13 in | Width: 7.25 in | Height: 6.0 in
- Weight
- 0.009 kg (0.02 lb)
- Other Technical Attributes
- Meets OEM Specifications
What’s in the Box
- 1 x Gasket (27-78690002)
Installation Notes
- Ensure the engine is off, cool, and disconnected from the power source.
- Locate the relief valve cover on the engine block.
- Carefully remove the bolts securing the cover.
- Pry off the old cover and gasket, taking care not to gouge the mating surfaces.
- Thoroughly clean any old gasket material or sealant from both the engine block and the cover.
- Position the new gasket correctly on the engine block.
- Place the cover over the new gasket and align the bolt holes.
- Tighten the bolts in a crisscross pattern to the manufacturer's recommended torque specification.
- Reconnect the power, start the engine, and check for any leaks around the cover.
Troubleshooting & FAQ
How do I confirm this gasket fits my specific engine model?
The most reliable method is to check your engine's serial number against the ranges listed in the Engine & Model Compatibility table. If your model and serial number fall within the specified range, the part will fit.
What are the signs of a failing relief valve cover gasket?
Common symptoms include visible water leaks around the relief valve cover, engine overheating issues, or low water pressure readings. A visual inspection may reveal a cracked, brittle, or compressed old gasket.
Do I need to use sealant with this gasket?
This gasket is typically designed for a dry installation. However, always consult your engine's official service manual, as some specific models or repair situations might call for a light application of a particular sealant.
Can I reuse my old gasket after removing the cover?
No. Gaskets are single-use components that crush to create a unique seal. Once compressed and heat-cycled, they lose their ability to seal effectively and must be replaced whenever the component is removed.
What is the function of the relief valve this gasket seals?
The pressure relief valve (or poppet valve) helps regulate engine temperature at different RPMs by controlling water flow through the cooling system. A proper seal is critical for preventing leaks and maintaining correct engine operating temperature.
The compatibility table mentions serial numbers. Where can I find this on my engine?
The engine serial number is usually located on a metal plate or sticker on the transom mounting bracket. It can also be found on the engine block itself.
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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