Mercury MerCruiser Quicksilver Thermostat Housing Gasket 806871
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Mercury MerCruiser Quicksilver 27-806871 is a thermostat housing gasket used on select MerCruiser gasoline engines. It seals the thermostat housing area to help control coolant flow and prevent leaks around the thermostat assembly. Mercury parts references show 806871 as superseded, with current diagram references commonly listing 8M0238323 and earlier replacement references showing 8M0204687 as the functional replacement.
Key Features
- Genuine Mercury / Quicksilver thermostat housing gasket reference
- Used in select MerCruiser standard cooling system and thermostat housing assemblies
- Helps seal the thermostat housing during cooling-system service
- Original Mercury reference: 27-806871 / 806871
- Replacement references include 27-8M0204687 and 27-8M0238323
- GTIN reference for 806871 / 8M0204687: 745061284968
- Catalog shipping reference for 8M0204687: approximately 0.02 lb, 2.00 in. x 2.00 in. x 0.20 in.
Engine Compatibility
This gasket is commonly shown for select MerCruiser gasoline engines, including many 3.0L GM 181 I/L4, 4.3L V6, 5.0L / 5.7L GM V8, 6.2L, 7.4L, 8.2L, Black Scorpion, Scorpion, MAG, MPI, Alpha, Bravo, and inboard applications depending on serial number and thermostat housing design. Cross-reference descriptions also identify this gasket for V6 and V8 MerCruiser stern drive and inboard engines using the newer-style thermostat housing, plus select 4.5L MPI and 6.2L MPI applications by serial range.
Serial Number Fitment Notice
Thermostat housing gasket fitment depends on the exact engine model, cooling-system layout, thermostat housing style, and serial number range. Always confirm compatibility using the MerCruiser engine serial number before ordering, especially where 27-806871 has been replaced by newer references such as 27-8M0204687 or 27-8M0238323.
When This Part Needs Replacement
Replace this gasket whenever the thermostat housing is removed, during thermostat replacement, or when there are signs of coolant leakage, gasket swelling, tearing, compression, corrosion marks, or seepage around the housing. Reusing an old thermostat housing gasket can cause a small leak that turns into repeat cooling-system service.
Installation Notes
Clean both thermostat housing mating surfaces before installation and remove old gasket material carefully without gouging the housing. Inspect the thermostat, sleeve, lower housing gasket, plugs, hoses, clamps, and related cooling-system hardware while the housing is apart. Install using the correct orientation and follow the Mercury service manual torque procedure for the specific engine.
Alternate / Superseded Part Numbers
- 27-806871
- 806871
- 27-806871Q
- 806871Q
- 27-8M0204687
- 8M0204687
- 27-8M0238323
- 8M0238323
Parts Desk Insight
This gasket is best matched by thermostat housing style, not just engine size. MerCruiser used different cooling-system layouts across similar-looking engines, so checking the serial-number diagram before ordering is the safest way to avoid getting the wrong thermostat gasket.
Shipping: Ships same or next day for fast Canada wide shipping. ā
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3ā4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
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