Quicksilver — Intake Manifold & Valley Gasket Set 8.1L 496 MAG — 27-881633T01
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The Mercury MerCruiser Quicksilver 27-881633T01 Intake Manifold and Valley Gasket Set is a genuine OEM replacement gasket kit for GM-based 8.1L big-block MerCruiser and Mercury inboard marine engines. This kit seals the intake manifold and lower lifter-valley area, helping prevent intake leaks, oil seepage, and contamination around the engine valley during intake manifold service. It replaces the earlier Mercury part number 27-881633001.
Key Features
- Mercury / Quicksilver part number: 27-881633T01
- Short part number: 881633T01
- Product type: Intake manifold and valley gasket set
- OEM status: Genuine Mercury MerCruiser / Quicksilver replacement kit
- Primary service area: Intake manifold and engine valley sealing surfaces
- Supersedes / replaces: 27-881633001
- Engine family: GM-based 8.1L big-block MerCruiser / Mercury marine V8 engines
- Application type: Inboard and sterndrive marine engine gasket service
Engine Compatibility
This gasket set is intended for select Mercury MerCruiser and Mercury inboard 8.1L big-block marine engines where the parts diagram calls for 27-881633T01, including:
- MerCruiser MCM 496 MAG
- MerCruiser MCM 496 MAG HO
- Mercury MIE 8.1S Horizon
- Mercury MIE 8.1S HO
Fitment must be confirmed by engine serial number, model designation, and Mercury parts diagram before ordering.
Serial Number Fitment Notice
Mercury gasket kits are engine-serial-specific. Confirm the engine serial number and parts diagram before purchase, especially on 8.1L / 496 MAG engines where model year, cooling configuration, intake layout, and service history can affect which gasket set is correct.
Do not select this kit by displacement alone. The correct match is based on the Mercury engine serial number and diagram callout.
When This Part Needs Replacement
Replace this gasket set whenever the intake manifold is removed or the valley cover area is disturbed. It should also be replaced if there are signs of intake vacuum leaks, oil weeping around the engine valley, coolant or oil contamination concerns, rough running after intake service, visible gasket deterioration, or seepage from the intake sealing surfaces.
Old intake and valley gaskets should not be reused after disassembly, as compression set, heat cycling, oil exposure, and age can prevent proper resealing.
Installation Notes
Clean all gasket surfaces thoroughly before installation and inspect the intake manifold, cylinder head sealing faces, valley cover area, fasteners, and adjacent hoses before reassembly. Do not gouge aluminum sealing surfaces during gasket removal.
Follow the current Mercury MerCruiser service manual for intake manifold removal, gasket placement, sealant requirements, bolt tightening sequence, and torque specifications. If this repair is being performed due to an oil leak or running issue, inspect related intake hardware, sensors, PCV/breather components, and cooling-system connections while the intake is accessible.
Alternate/Superseded Part Numbers
- Current Mercury / Quicksilver number: 27-881633T01
- Short number: 881633T01
- Superseded Mercury number: 27-881633001
- Common description: Intake Manifold & Valley Gasket Set
- Application reference: MerCruiser 496 MAG / 496 MAG HO and Mercury MIE 8.1S Horizon / 8.1S HO engines
Parts Desk Insight
The important check on this kit is the engine serial number. The 8.1L / 496 family has several related gasket and intake-service parts, and similar-looking components may not match every model year or configuration. Confirm the serial number before ordering so the intake manifold and valley gaskets match the exact Mercury parts diagram.
Shipping: Ships same or next day for fast Canada wide shipping. ⚓
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
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We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
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