Sierra 18-2917-9 Thermostat Housing Gasket - Pack of 2 for MerCruiser MCM/MIE GM V-6 & V-8 Engines

The Sierra 18-2917-9 is a thermostat housing gasket for marine inboard engines, sold as a pack of 2 so you have a spare or can service both the thermostat housing and a related joint in the same job. It is designed to seal the thermostat housing against the cylinder head or manifold, preventing coolant loss and maintaining proper engine operating temperature. The gasket has a round profile sized to match the thermostat housing bore and bolt pattern on the engines it is built for.

This gasket fits MCM/MIE GM V-6 and V-8 marine engines. It is specifically listed for 5.7L MIE engines, including engine model F622100 (serial number 0K999999) and engine model L002003 and up, where it is used alongside companion gasket part numbers 18-3647 and 18-3649 in the thermostat housing assembly. Replacing a worn or hardened thermostat housing gasket is a routine part of cooling system maintenance and is typically done any time the thermostat housing is removed for inspection, cleaning, or thermostat replacement, to ensure a leak-free reseal.

Sold under Sierra's marine engine parts line, this gasket is identified by UPC 808282164195 and is built to be a direct fit for the engines and thermostat housings listed above.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-2917-9
• Product Type: Thermostat Housing Gasket
• Pack Quantity: 2
• Shape: Round
• Material: Other
• Weight: 0.02 pounds
• UPC: 808282164195
• GTIN: 00808282164195
• Fits: MCM/MIE GM V-6 and V-8 engines

Fitment

• 5.7L MIE, engine model F622100, serial number 0K999999
• 5.7L MIE, engine model L002003 and up
• MCM/MIE GM V-6 and V-8 engines

Frequently Asked Questions

What engines does the Sierra 18-2917-9 thermostat gasket fit? The 18-2917-9 fits MCM/MIE GM V-6 and V-8 marine engines, and is specifically listed for 5.7L MIE engines under engine model F622100 (serial number 0K999999) and engine model L002003 and up.

How many gaskets come in one package? Sierra part 18-2917-9 is sold as a pack of 2 thermostat housing gaskets, giving you enough for the job plus a spare.

What is the shape of this gasket? This thermostat housing gasket is round in shape, matching the profile of the thermostat housing bore it seals.

How much does the 18-2917-9 gasket weigh? Each package of the Sierra 18-2917-9 thermostat gasket weighs 0.02 pounds.

Is this gasket a genuine Sierra part? Yes, part number 18-2917-9 is a Sierra branded thermostat housing gasket, not a generic substitute.

What other parts are used with the 18-2917-9 gasket in the thermostat housing assembly? On 5.7L MIE engines, the 18-2917-9 gasket is used together with companion gasket part numbers 18-3647 and 18-3649 in the thermostat housing assembly.

Does the UPC on this gasket match the packaging I should expect? Yes, the Sierra 18-2917-9 thermostat gasket carries UPC 808282164195, which you can check against the packaging to confirm you have the correct part.

When should I replace the thermostat housing gasket? The 18-2917-9 gasket should be replaced any time the thermostat housing is removed, such as during thermostat replacement or cooling system service, since a used gasket will not reseal reliably.

Will this gasket fit non-MIE MerCruiser engines? The 18-2917-9 is listed for MCM/MIE GM V-6 and V-8 engines, with confirmed fitment on 5.7L MIE models F622100 and L002003 and up; fitment outside of those engines is not specified.

What material is the 18-2917-9 gasket made from? The material for the Sierra 18-2917-9 thermostat gasket is listed simply as Other, without a more specific composition given by the manufacturer.