Exhaust Riser Gasket – Fits MerCruiser 2.5L-3.0L & Various GM/Ford V-8 Engines (Replaces 27-99777, 27-997771, 27-997772)
Exhaust Riser Gasket – Fits MerCruiser 2.5L-3.0L & Various GM/Ford V-8 Engines (Replaces 27-99777, 27-997771, 27-997772) 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.).
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
Exhaust Riser Gasket – Fits MerCruiser 2.5L-3.0L & Various GM/F...
Product Details
This Exhaust Riser Gasket creates a secure seal between the exhaust manifold and the riser or elbow. It is designed for a wide range of engines, including MerCruiser GM 2.5L and 3.0L inline 4-cylinder models, GM V-8 small block engines (1982 and older), Ford V-8 engines, and specific Mercury Marine models like the MCM 120 (1983 and newer), 140/3.0L, 470, and 165 In-Line 6-Cylinder.
This part serves as a direct replacement and interchange for OEM part numbers 27-99777Q02, 27-99777, 27-997771, and 27-997772, ensuring a precise fit for compatible models.
- Installs between the exhaust manifold and the corresponding riser/elbow.
- Engineered to meet or exceed original equipment manufacturer specifications.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Superseded By |
|---|---|---|
| Mercury Marine / MerCruiser | 27-99777 | 27-99777Q02 |
| Mercury Marine / MerCruiser | 27-997771 | 27-99777Q02 |
| Mercury Marine / MerCruiser | 27-997772 | 27-99777Q02 |
| Mercury Marine / MerCruiser | 27-99777Q02 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For MerCruiser (Mercury Marine / Quicksilver) engines, this gasket fits a variety of inline, V-6, and V-8 models as detailed in the compatibility list.
| Brand | Model | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|
| MerCruiser | GM Inline 4 Petrol | 4-Stroke | 27-99777Q02 | Used on 2.5L and 3.0L engines | |
| MerCruiser | MCM 120 | 1983 and newer | 27-99777Q02 | ||
| MerCruiser | 140/3.0L | 27-99777Q02 | |||
| MerCruiser | 470 | 27-99777Q02 | |||
| MerCruiser | 165 In-Line | 27-99777Q02 | 6 Cyl engine | ||
| MerCruiser | GM V-8 Small Block | 1982 and older | 27-99777Q02 | ||
| MerCruiser | Ford V-8 Engines | 27-99777Q02 |
Technical Specs
- Product Type
- Exhaust Riser Gasket
- Installation Location
- Between exhaust manifold and riser/elbow
- Dimensions
- Height: 6.0 in; Width: 7.5 in; Length: 1.13 in
- Weight
- 0.08 lb (0.036 kg)
What’s in the Box
- 1x Exhaust Riser Gasket
Installation Notes
- Ensure the engine is completely cool and disconnect the battery for safety.
- Drain the cooling system as needed to access the exhaust components without spillage.
- Carefully unbolt and remove the exhaust riser/elbow from the exhaust manifold.
- Remove the old gasket and thoroughly clean both mating surfaces. Ensure they are free of any old gasket material, rust, or debris.
- Position the new gasket, verifying it aligns correctly with the ports.
- Reinstall the riser/elbow and tighten the bolts in a crossing pattern to the manufacturer's specified torque values.
- Reconnect the battery, refill the cooling system, and run the engine to check for any exhaust or water leaks.
Troubleshooting & FAQ
How can I confirm this gasket fits my specific engine?
Please review the "Engine & Model Compatibility" table on this page. Cross-reference your engine's brand, model, and year to ensure a correct match. Verifying the OEM part number is the most reliable method.
Do I need to use a sealant with this gasket?
Most modern exhaust gaskets of this type are designed to be installed dry. However, always consult your specific engine's service manual, as it provides the definitive recommendation on sealant use.
What are the signs of a failing exhaust riser gasket?
Common symptoms include visible water leaks from the joint between the manifold and riser, steam around the manifold area, engine overheating, and in severe cases, water intrusion into the cylinders, which can cause 'milky' engine oil.
How often should this gasket be replaced?
The gasket should be replaced any time the exhaust riser or manifold is removed. In saltwater environments, it is recommended to inspect these components annually for corrosion and replace gaskets as a preventive measure.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. The part is manufactured in an ISO 9002 facility and is batch-inspected for consistency.
Shipping speed & cost?
We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free; expedited options will appear at checkout where available.
Warranty & returns?
This product is covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact our support team with your order details. Returns are accepted within our standard window for items that are unused and in their 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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