Mercury – Quicksilver Exhaust Manifold and Plate Diaphragm | Exhaust System Component | Heat-Resistant Composite | 144791

Overview

When your outboard is working hard, the exhaust system takes a beating. The Mercury Marine 144791 Quicksilver Exhaust Manifold and Exhaust Plate Diaphragm helps keep that system sealed, balanced, and breathing the way it should. Built for Mercury and Mariner 105–225 horsepower TwoStroke outboards, this part maintains proper exhaust pressure and cooling flow inside your engine’s 2.5L powerhead. It’s one of those small, critical components that keep performance engines running smooth, cool, and consistent trip after trip.

Key Features

• Purpose: Maintains exhaust pressure balance between the manifold and plate for efficient flow and cooling.
• Material: Constructed from heat-resistant composite designed to endure marine temperatures and vibration.
• Design Detail: Precision molded to OEM Mercury Marine specifications for a perfect fit and reliable sealing.
• Durability: Resists cracking, warping, and chemical wear from exhaust gases and fuel residue.
• Compatibility: Fits Mercury and Mariner 105–225HP TwoStroke EFI, DFI, Laser, Magnum II & III, Pro Max, SuperMAG, Jet, and Pro XS (2.5L) outboards.
• Performance: Ensures consistent exhaust scavenging, helping maintain smooth throttle response and optimal engine temperature.

Engine & Boat Compatibility

• Designed for Mercury and Mariner TwoStroke outboards from 105HP to 225HP (2.5L), including:
• EFI and DFI models
• Laser, Magnum II & III
• Pro Max, SuperMAG, Jet, and Pro XS variants
  
  
• Common on bass boats, performance hulls, and high-output sport boats that run Mercury’s 2.5L powerheads.
• Works in both freshwater and saltwater applications.
• Refer to your owner’s or service manual for model-specific fitment.

Performance & Practical Benefits

This diaphragm helps your engine breathe correctly, managing exhaust backpressure to keep power delivery steady. It also helps regulate cooling water flow in the exhaust passages, preventing overheating under sustained load. The composite material is built to handle intense heat and pressure without losing its shape or seal.

Replacing a worn or cracked diaphragm restores smooth idle, crisp throttle response, and consistent midrange performance. The difference shows up in quieter operation and fewer fluctuations when you’re running at speed. It’s a small part that has a big influence on how your outboard feels and performs day to day.

Why Buy OEM

Aftermarket exhaust components can vary in thickness or material quality, which can throw off your engine’s tuning and exhaust balance. The Quicksilver 144791 is a genuine Mercury Marine part, built from materials tested specifically for high-performance 2.5L Mercury engines. Its fit, flexibility, and heat resistance match the factory part exactly — no guesswork, no compromises.

Mercury’s OEM design ensures consistent backpressure and precise sealing, protecting your engine from leaks and uneven performance. For those who rely on their outboard to run hard and run right, OEM isn’t optional — it’s essential.

FAQ

Q1: Which engines use this diaphragm?
It fits Mercury and Mariner 105–225HP TwoStroke 2.5L outboards, including EFI, DFI, Laser, Pro Max, SuperMAG, Jet, and Pro XS models.

Q2: What makes it different from aftermarket options?
It’s built to Mercury’s OEM standards, using heat-resistant materials that won’t warp or degrade under exhaust heat.

Q3: How can I confirm fitment for my engine?
Check your owner’s manual or match your existing part to 144791 to verify compatibility.

Q4: Can it handle saltwater use?
Yes. It’s designed to resist corrosion and maintain sealing in both salt and freshwater environments.

Q5: Is installation straightforward?
Yes. Follow your service manual for torque and gasket replacement instructions during reassembly.