Cylinder Head Gasket – Fits Mercury/Mariner 175-200 HP XR6 (Replaces 27-822844T04, 27-822844T05)

$34.99 $55.00

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Cylinder Head Gasket – Fits Mercury/Mariner 175-200 HP XR6 (Replaces 27-822844T04, 27-822844T05) is backordered and will ship as soon as it is back in stock.

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Product Details

This aftermarket Cylinder Head Gasket is engineered for a precise fit on a range of Mercury/Mariner 150-200 HP V6 2.5L 2-Stroke outboards from 1992 to 2005, including XR6 and Magnum III models. It also fits Mercury Sport Jet 175 HP 2-Stroke engines from 1997–1999. It forms a critical seal between the cylinder head and the engine block, preventing combustion gas leaks and coolant or oil mixing.

This gasket is a direct replacement for multiple part numbers, including Mercury 27-822844T04, 27-822844T05, 27-822844-1, 27-184721, Sierra 18-3864, GLM 35870, and Mallory 9-63854.

Installs between the cylinder head and engine block.
Made from durable composite material to withstand engine pressures.
Designed for engines with a 3.501" piston diameter.

Part Number Matrix

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

Brand	Part Number	Superseded By
Mercury	27-822844T04	27-822844T05
Mercury	27-822844T05
Mercury	27-822844-1
Mercury	27-184721
Sierra	18-3864
GLM	35870
Mallory	9-63854

Engine & Model Compatibility

Confirm your engine model and year in the table below.

Mercury/Mariner Outboard:

Sport Jet:

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
Mercury/Mariner	V-140 Jet	140	2-Stroke	1996–1998	27-822844T04/T05	Serial Range: 0D082000-0G960499
Mercury/Mariner	V-150 (XR6/Magnum III)	150	2-Stroke	1992–1995	27-822844T04/T05	Serial Range: 0D082000-0G960499
Mercury/Mariner	V-150 EFI	150	2-Stroke	1993–1998	27-822844T04/T05	Serial Range: 0D082000-0G960499
Mercury/Mariner	V-150 EFI	150	2-Stroke	1996–1998	27-822844T04/T05	Serial Range: 0G960500-0T408999
Mercury/Mariner	V-175	175	2-Stroke	1992–2002	27-822844T04/T05	Serial Range: 0D082000-0G960499, C239553 & up
Mercury/Mariner	V-175 EFI	175	2-Stroke	1992–1995	27-822844T04/T05	Serial Range: 0D082000-0G960499
Mercury/Mariner	V-200	200	2-Stroke	1991	27-822844T04/T05	Serial Range: 0C291520-0D081999
Mercury/Mariner	V-200	200	2-Stroke	1992–2005	27-822844T04/T05	Serial Range: 0D082000 & up
Mercury/Mariner	V-200 EFI	200	2-Stroke	1991	27-822844T04/T05	Serial Range: 0C291520-0G960499
Mercury/Mariner	V-200 ProMax	200	2-Stroke	1992–1998	27-822844T04/T05	Serial Range: 0D935000-0G610079 & 0G857000 & up
Mercury/Mariner	XR6	150-175	2-Stroke	1992–2002	27-822844T04/T05	Serial Range: 0D082000 & up
Mercury	Sport Jet	175	2-Stroke	1997–1999	27-822844T04/T05

Technical Specs

Product Type: Cylinder Head Gasket
Installation: Between cylinder head and block
Fuel Type: Gasoline
Housing Material: Composite
Thickness: 1.2 mm
Product Dimensions: 16.5" L x 6.0" W x 0.13" H
Fitting Type: Direct replacement
Working Pressure: Engine compression rated
Other Technical Attributes: For 3.501" piston diameter

What’s in the Box

1 x Cylinder Head Gasket (Replaces 27-822844T04/27-822844T05)

Installation Notes

Disconnect the battery and drain the engine coolant completely.
Carefully remove the cylinder head cover and any interfering components.
Unbolt and remove the cylinder head, taking note of the bolt sequence.
Remove the old gasket and thoroughly clean both the engine block and cylinder head surfaces. Ensure they are free of any old material, oil, or debris.
Position the new gasket correctly on the engine block; do not use any sealant unless specified by the engine manufacturer.
Carefully reinstall the cylinder head and tighten the bolts in the specified sequence and to the correct torque values.
Reassemble all other components, refill the coolant, and reconnect the battery.
Start the engine and check for any leaks around the gasket area.

Troubleshooting & FAQ

How do I know if my cylinder head gasket is failing?

Common signs of a blown head gasket include engine overheating, white smoke from the exhaust (burning coolant), milky or frothy engine oil, unexplained coolant loss, or a loss of engine compression and power. A compression test is a reliable way to diagnose the issue.

Is this gasket reusable?

No. Cylinder head gaskets are designed for one-time use. They crush and conform to the surfaces to create a seal. Once torqued and heat-cycled, they must be replaced if the head is removed.

Will this fit my specific XR6 model?

This gasket fits Mercury/Mariner XR6 models with 150-175 HP made from 1992-2002 with serial numbers 0D082000 and up. Always verify your serial number against the compatibility table to ensure an exact match.

Do I need to use sealant with this gasket?

Generally, modern composite gaskets like this one are designed to be installed dry. Applying sealant can interfere with the seal and cause premature failure. Always follow your engine's service manual for specific instructions.

What is the difference between part 27-822844T04 and 27-822844T05?

Part number 27-822844T05 is the official supersession for 27-822844T04. This means it is the newer, recommended replacement from the manufacturer, offering the same or improved performance and fitment.

When should I replace my head gasket?

A head gasket does not have a set replacement interval and is typically only replaced when it fails. However, it should always be replaced whenever the cylinder head is removed for other service or repairs.

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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