Gasket – Fits Mercury Marine Outboard Motors (Replaces 27-991772, 27-991771)

$20.67 $33.00

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Product Details

This Gasket – Fits Mercury Marine Outboard Motors (Replaces 27-991772, 27-991771) provides a reliable seal for various Mercury Marine V-6 engines from 150-200 HP, covering models manufactured between 1978 and 1989. It is engineered to ensure optimal performance and prevent leaks between critical engine components.

The part directly supersedes and interchanges with Mercury OEM part numbers 27-991772, 27-991771, 27-99177, and 27-78068.

Installation Location: Mounts between the drive shaft housing plate and the exhaust plate.
Precise Dimensions: Engineered to 13.00 x 10.00 x 0.13 inches for an exact fit.
Ready to Install: Includes one high-quality gasket for a complete replacement.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket brands.

Brand	Part Number	Superseded By	Notes
Mercury	27-78068	27-99177
Mercury	27-99177	27-991771
Mercury	27-991771	27-991772
Mercury	27-991772		Current part number

Engine & Model Compatibility

Confirm your engine model and year in the table below to ensure compatibility.

For Mercury/Mariner Outboard Models, please verify your specific model, horsepower, and serial number range against the details listed.

Brand	Model	Rated HP	Years	OEM Part No.	Notes
Mercury	V-150	150	1978–1985	27-991772	Serials 4868998 through 0A904645
Mercury	V-150	150	1978–1985	27-991772	Serials 5600162 through 0A904645
Mercury	V-150 Magnum	150	1978–1985	27-991772	Serials 5600162 through 0A904645
Mercury	V-150 Marathon	150	1978–1985	27-991772	Serials 5600162 through 0A904645
Mercury	V-150 Work	150	1978–1985	27-991772	Serials 4868998 through 0A904645
Mercury	V-1500	150	1978–1985	27-991772	Serials 4868998 through 0A904645, Serials 5600162 through 0A904645
Mercury	V-150-XR-2	150	1978–1985	27-991772	Serials 4868998 through 0A904645
Mercury	V-175	175	1976–1988	27-991772	Serials 4301235 through 0C100860, Serials 8058870 & Up
Mercury	V-200	200	1978–1988	27-991772	Serials 0C100861 through 0C291519, Serials 5624878 through 0C100860

Technical Specs

Product Type: Gasket
Installation: Drive Shaft Housing Plate to Exhaust Plate
Dimensions: 13.00 x 10.00 x 0.13 inches (330.2 x 254.0 x 3.3 mm)
Weight: 0.19 lbs (0.086 kg)
OEM Part Number: 27-991772

What’s in the Box

1 x Gasket (Replaces 27-991772)

Installation Notes

Ensure the engine is completely cool and disconnect the battery before starting.
Access the drive shaft and exhaust plate assembly according to your engine's service manual.
Carefully remove the old gasket and thoroughly clean both mating surfaces. Any old material or debris can cause leaks.
Place the new gasket into position. Do not use sealant unless explicitly required by your service manual.
Reassemble the components, tightening all fasteners to the manufacturer's specified torque in the correct sequence.
After reassembly, reconnect the battery and check for water or exhaust leaks before operating the engine under load.

Troubleshooting & FAQ

How do I know if this gasket will fit my Mercury engine?

The surest way to confirm fitment is to check the Engine & Model Compatibility table. Locate your engine's model, horsepower, and year. Most importantly, verify that your engine's serial number falls within the specified range for that model.

What are common signs of a failed exhaust plate gasket?

Symptoms of a bad gasket include visible water leaks around the exhaust plate area (especially when running), engine overheating, loss of power, or an unusually loud or sputtering exhaust sound.

Is this gasket made from the same material as the original?

This part is designed to meet or exceed OEM specifications. It is made from comparable, high-quality materials selected for durability and to provide a reliable seal in a marine environment.

Should I use sealant when installing this gasket?

Generally, this type of gasket is designed to be installed dry on clean, flat surfaces. However, we always recommend consulting your engine's official service manual for model-specific instructions, as some applications may have unique requirements.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, it is batch-inspected for consistency and quality.

Shipping speed & cost

We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free; expedited options appear at checkout where available.

Warranty & returns

This product is covered by a 1-year warranty against manufacturing defects under normal use. If any issues arise, contact our support team with your order details. Returns are accepted within our standard window, provided the item is unused and in its original condition. Please 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

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