• 2778690002 Mercury MerCruiser Relief Valve Cover Gasket | Genuine Quicksilver OEM Part
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2778690002 Mercury MerCruiser Relief Valve Cover Gasket | Genuine Quicksilver OEM Part

2778690002 Mercury MerCruiser Relief Valve Cover Gasket | Genuine Quicksilver OEM Part

$6.90 AUD
$6.90 AUD
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🔧 Product Description

Genuine Quicksilver Relief Valve Cover Gasket - Part Number: 27-78690002

A genuine Quicksilver relief valve cover and plate gasket for Mercury V6 outboard cooling-system relief valve assemblies. This gasket seals the poppet / relief valve cover area to help maintain correct cooling-water pressure and prevent leakage at the cover joint.

⚙️ Key Features

  • Genuine Quicksilver OEM gasket
  • Correct Mercury part number 27-78690002
  • Relief valve cover and plate gasket for Mercury V6 cooling systems
  • Also referenced as 27-78690, 27-78690002 and 2778690002
  • Cross-referenced with Sierra, Mallory and GLM gasket equivalents

🚤 Compatibility

Commonly used on

  • Mercury V6 2.5L cooling-system relief valve / poppet valve cover assemblies
  • Mercury DFI, EFI, Pro XS, Jet Drive and high-performance V6 outboard applications using 27-78690002

Typically suits

  • Engine models:
  • Mercury 200 DFI Jet Drive powerhead - serial 0E435742 and up
  • Mercury 200 DFI Jet Drive powerhead - serial 1B321662 to 1B321669
  • Mercury 200 DFI Jet Drive pump - serial 0M964699 and up
  • Mercury 200 DFI M2 Jet Drive pump - serial 0M965234 and up
  • Mercury Magnum III - serial 0G960500 to 1B226999
  • Mercury V-135 - serial 0G960500 to 0T178499
  • Mercury V-135 DFI 2.5L - serial 0T801000 to 1B226999
  • Mercury V-135 DFI 2.5L - serial 1B227000 to 1B417701
  • Mercury V-135 DFI 2.5L - serial 1B417702 and up
  • Mercury V-140 International - serial 0T178500 to 1B226999
  • Mercury V-150 - serial 0G960500 to 1B226999
  • Mercury V-150 DFI 2.5L - serial 0T801000 to 1B226999
  • Mercury V-150 DFI 2.5L - serial 1B227000 to 1B417701
  • Mercury V-150 DFI 2.5L - serial 1B417702 and up
  • Mercury V-150 EFI 2.5L - serial 0T801000 to 1B226999
  • Mercury V-150 EFI 2.5L - serial 1B227000 and up
  • Mercury V-175 DFI 2.5L - serial 0T801000 to 1B226999
  • Mercury V-175 DFI 2.5L - serial 1B227000 to 1B417701
  • Mercury V-175 DFI 2.5L - serial 1B417702 and up
  • Mercury V-200 - serial 0G960500 to 1B226999
  • Mercury V-200 EFI 2.5L - serial 0T801000 to 1B226999
  • Mercury V-200 EFI 2.5L - serial 1B227000 and up
  • Mercury XR-6 - serial 0G960500 to 1B226999
  • Mercury 200XS DFI 2.5L - serial 0T818181 to 1E000796
  • Mercury 200XS DFI 2.5L - serial 1E000797 to 1E002110
  • Mercury 200XS DFI 2.5L ROS - serial 1E050852 and up
  • Mercury 200XS SST - serial 1E050629 and up
  • Mercury 225X EFI ProMax - serial 0T430254 to 0T819605
  • Mercury 110 Jet 2.5L - serial 1B690542 and up
  • Mercury 140 Jet - serial 0G960500 to 0T178499
  • Mercury 150 Pro XS 2.5L - serial 1B690542 and up
  • Mercury 175 Pro XS 2.5L - serial 1B516339 and up
  • HP Range: commonly 110HP - 225HP where 27-78690002 is specified
  • Engine Type: Mercury V6 2-stroke, EFI and DFI outboard cooling system
  • System Type: Relief valve / poppet valve cover gasket

🔌 Function

The relief valve cover gasket seals the cooling-system relief valve cover and plate so the valve can regulate cooling-water pressure without leakage at the cover joint.

⚠️ Common Signs of Failure

  • Water leaking from the relief valve cover area
  • Cooling-water pressure loss
  • Overheating at idle or under load
  • Salt build-up around the poppet valve cover
  • Gasket damage during relief valve service

🔄 Supersession & Cross Reference

OEM Supersession Chain

  • 27-78690002 current OEM service reference
  • 27-78690 earlier / related OEM relief valve cover gasket reference
  • 27-67624 earlier related relief valve cover gasket reference

OEM / Related Numbers

  • 27-78690002
  • 78690002
  • 2778690002
  • 27-78690
  • 78690
  • 27-67624
  • 67624

Aftermarket / Verified Equivalents

  • Sierra: 18-0936
  • Mallory: 9-60057
  • GLM: 31990

📦 Condition

  • Genuine Quicksilver part
  • Brand new
  • Supplied in original or equivalent packaging

Shipping & Delivery

Flat-rate shipping Australia-wide — $14.99 per order, no matter how many parts you add. Orders dispatch from our Kadina, South Australia store. Need it urgently or want to collect in person? Call us on 0412 532 984 before ordering.

Returns & Warranty

14-day change-of-mind returns — if it's not right or you ordered the wrong part, send it back within 14 days in new, unused condition for a refund or exchange. Manufacturer warranties apply to new parts. Full details in our Refunds & Returns policy.

Not sure this fits?

Ask us before you buy — we check part numbers and fitment every day. Call 0412 532 984 (Mon–Fri 8.30am–4.30pm) or message us through the contact page with your engine or vehicle details.

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