Mercury MerCruiser Quicksilver Exhaust Manifold End Cap Gasket 480431

Exhaust Manifold End Cap / Connector Gasket — OEM Reference 480431 / 27-480431

Part Number: 480431 | Service format: 27-480431
Brand: Mercury Marine / Quicksilver
Official Product Type: Exhaust Manifold End Cap / Connector Gasket
Supersedes: 48043 / 27-48043 / 27-48043-1
Replaced By: 480431 is the current active part number
System: Exhaust & Cooling — Manifold End Cap / Thermostat Housing Interface
Diagram Position: Between exhaust manifold and end cap / connector; also used as thermostat-housing-to-exhaust-manifold gasket in applicable configurations
GTIN: 745061155732

What This Gasket Does

This genuine Mercury Marine / Quicksilver gasket seals the joint between the exhaust manifold and its end cap or connector on select older MerCruiser inboard and sterndrive engines. In some exhaust and cooling configurations it also seals the thermostat housing to the exhaust manifold. It replaced earlier gasket number 48043. A generic cut gasket may not match the cooling-water passages, bolt pattern, or compressed thickness of the OEM part — which can result in exhaust or water leakage, especially on older manifolds where sealing surfaces may have some corrosion or pitting.

Compatible Applications

Fitment depends on exact engine model, serial number, exhaust manifold style, and diagram position. Confirm against your MerCruiser parts diagram before ordering.

• MerCruiser 120 / 2.5L (GM 153 inline-four)
• MerCruiser 140 / 3.0L (GM 181 inline-four)
• MerCruiser 165 (GM 250 inline-six)
• MerCruiser 200 (GM 292 inline-six)
• MerCruiser 470 (Mercury 224 inline-four)
• Selected older GM 305, 327, 350, 427, 454, and 482 V8 MerCruiser applications
• Other MerCruiser exhaust manifold, elbow, and cooling-system assemblies where diagram calls for 480431

Serial Number Fitment Notice

Mercury used 480431 in more than one sealing position — the same gasket can appear as an end-cap gasket in one assembly and a thermostat-housing gasket in another. Always confirm the exact diagram position by engine serial number before ordering.

When to Replace This Gasket

Replace whenever the exhaust manifold end cap, connector, or applicable thermostat housing is removed. Also replace if there is evidence of water seepage, exhaust leakage, gasket deterioration, or corrosion at the mating surfaces. Reusing a disturbed exhaust manifold gasket — especially on an older cast manifold — is not recommended.

Service Interval

Replace at every exhaust manifold end cap or thermostat housing removal. Exhaust gaskets are single-use components and should never be reused once disturbed.

Dimensions

Approximate: 3.78 in. × 3.78 in. × 0.25 in. | Weight: approx. 0.01 lb (0.005 kg)

Installation Notes

• Clean both mating surfaces completely and remove all traces of the old gasket before installation.
• Inspect the manifold, end cap, thermostat housing, fasteners, and water passages for corrosion or pitting.
• Install the gasket in the correct orientation shown in the applicable Mercury parts diagram.
• Tighten associated hardware to torque specifications in the MerCruiser service manual.
• Match by part number and diagram callout — not by shape alone, as similar-looking gaskets are used in nearby positions.

Kit Contents

Single gasket. Not a kit. Order all related manifold, elbow, thermostat housing, and end cap gaskets separately for a complete exhaust service.

Alternate and Superseded Part Numbers

• Current: 480431 / 27-480431
• Supersedes: 48043 / 27-48043 / 27-48043-1
• Aftermarket cross-reference: Sierra 18-2832

Related Parts

• Exhaust manifold end cap — verify by engine model and serial number
• Thermostat housing gasket — verify by engine model and serial number
• Exhaust manifold elbow gasket — verify by engine model and serial number
• MerCruiser thermostat — replace during manifold service if due

Parts Desk Insights

The key detail with this gasket is that it shows up in more than one position across different MerCruiser manifold configurations — end cap in one assembly, thermostat housing in another. Customers who order by shape or engine size alone sometimes get the right part number but install it in the wrong position. A quick serial-number lookup against the correct diagram confirms both the part and its exact location in the manifold stack. On older manifolds with surface corrosion, clean and inspect the mating faces before installation — a warped or pitted surface will compromise even a new OEM gasket.

Technical FAQ

Q: Can I reuse this gasket after removing the end cap?
No. Exhaust manifold gaskets are single-use. Once compressed and disturbed they will not re-seal reliably.

Q: Is 48043 the same gasket as 480431?
Yes — 480431 is the current OEM replacement for 48043. Order 480431 (or 27-480431) when sourcing this part today.

Q: This gasket is listed in two positions in my diagram — which one do I need?
You may need one for each position. Confirm both diagram callouts against your engine serial number — 480431 is used at both the end-cap and thermostat-housing positions in some manifold configurations.