MerCruiser Exhaust Manifold End Cap Gasket 807218 | 27-807218

Exhaust Manifold End Cap Gasket — Part 807218

This is the genuine OEM gasket that seals the joint between the exhaust manifold body and its removable end cap on a range of classic MerCruiser gasoline engines. It contains cooling water and exhaust gases within the manifold assembly at the end-cap interface. This gasket is specific to the end-cap position — not the manifold-to-cylinder-head joint or the manifold-to-riser joint, which use separate gaskets.

Supersedes / Part Number Reference

• Current OEM number: 807218 / 27-807218
• Supersedes: 73814 / 27-73814 and 738141 / 27-738141
• Aftermarket cross-references: Sierra 18-0928, Sierra 18-0928-1, GLM 30920, OMC 0508605

Compatible Applications

MerCruiser used several exhaust manifold and end-cap configurations within the same engine families. Confirm fitment by engine serial number and the applicable exhaust manifold diagram. Verify the number of gaskets required before ordering.

• MCM/MIE 120 / 2.5L GM 153 Inline-4
• MCM/MIE 140 / 3.0L / 3.0LX GM 181 Inline-4 — selected exhaust manifold assemblies specifying 807218 at the end-cap position
• MCM/MIE 165 Inline-6 / GM 250 / 292 families
• MerCruiser 470 / 3.7L / 224 CID
• MerCruiser 898
• MerCruiser 228
• MerCruiser 260
• Selected older GM V8 exhaust systems using the same removable end-cap manifold design

When This Part Needs Replacement

• The exhaust manifold end cap is removed for any reason
• Cooling water is leaking around the end-cap joint
• The gasket is crushed, torn, hardened, or deteriorated
• Corrosion is present around the end-cap sealing surface
• The exhaust manifold or end cap is being replaced
• Cooling-system service requires opening the manifold end cap

This gasket should be replaced whenever the end cap is removed — reusing a disturbed gasket risks a cooling water leak at the manifold.

Related Parts

• 805629A1 — Rear exhaust manifold end cap / lifting eye (search by part number)
• 73813A1 — Front or rear end-cap assembly depending on configuration (search by part number)
• 824941 — End-cap mounting screw (search by part number)
• 47483 — End-cap screw J-clip (search by part number)
• 96429 — Exhaust manifold-to-cylinder-head gasket (search by part number)
• 997772 — Exhaust elbow gasket on applicable configurations (search by part number)

Installation Notes

• Remove all traces of the old gasket from both the manifold body and the end cap
• Inspect the manifold and end-cap sealing surfaces for corrosion or pitting
• Check the end cap itself for distortion before reuse
• Verify whether your specific manifold uses one or two 807218 gaskets
• Inspect end-cap screws (824941) for corrosion and replace if needed
• Follow the applicable MerCruiser tightening sequence and torque specification for the end-cap fasteners
• Inspect for cooling water leakage after reassembly

Parts Desk Insights

Most common customer issue: Ordering this gasket when the manifold-to-head or manifold-to-riser gasket is the one that actually needs replacing. Classic MerCruiser exhaust assemblies use multiple gaskets in the same system — the end-cap gasket (807218), the head gasket (96429), and the elbow gasket (997772) are all different parts. If the leak is at the end of the manifold body where the cap screws on, 807218 is the right part. If it’s at the engine head or the elbow, you need a different gasket.

Best use case: Essential for anyone servicing a classic MerCruiser inline-4, inline-6, or compatible V8 exhaust manifold. If the end cap is coming off for any reason — cleaning, inspection, or manifold replacement — order a new 807218 before starting the job. It’s an inexpensive part that prevents a repeat cooling water leak.