Genuine Mazda Exhaust Manifold to Mid-Pipe Sealing Ring • L315-40-581

Genuine Mazda Exhaust Manifold to Mid-Pipe Sealing Ring

Replacement Genuine Mazda exhaust sealing ring for Mazda MX-5 Mk3, Mk3.5 and Mk3.75 NC models fitted with 1.8- or 2.0-litre petrol engines.

This cone-profile sealing ring fits between the exhaust manifold or front catalytic-converter assembly and the centre exhaust pipe. It seals the sprung exhaust connection and prevents combustion gases escaping beneath the vehicle.

The joint is retained by two bolts, springs and nuts. As the fasteners are tightened, the springs compress the sealing ring between the two exhaust sections while still allowing controlled movement as the system expands, contracts and moves with the engine.

One sealing ring is fitted per vehicle, and this listing supplies one Genuine Mazda component. The fastening bolts, springs, nuts, manifold assembly and centre exhaust pipe are supplied separately.

Important distinction: This is the sealing ring for the front exhaust manifold/catalytic-converter-to-mid-pipe joint. It is different from the flat gasket used between the centre pipe and rear silencer.

• Part type: Exhaust-joint sealing ring
• Common names: Exhaust doughnut gasket / converter-to-pipe seal / manifold lower seal / exhaust ring gasket
• Mazda catalogue description: Ring, Seal
• Location: Exhaust manifold/front catalytic converter to centre exhaust pipe
• Function: Seals the sprung front exhaust connection
• Profile: Cone-style sealing ring
• Quantity fitted per vehicle: 1
• Quantity supplied: 1 sealing ring
• Fastening bolts included: No
• Compression springs included: No
• Retaining nuts included: No
• Exhaust manifold included: No
• Centre exhaust pipe included: No
• Brand: Genuine Mazda
• Part No.: L315-40-581
• Previous Mazda reference: L307-40-581
• MX-5 fitment: All Mk3, Mk3.5 and Mk3.75 NC 1.8 and 2.0 models

Typical reasons for replacement:

• Exhaust blowing from the front pipe joint
• Visible soot deposits around the connection
• Sealing ring cracked, crushed or deteriorated
• Exhaust manifold or front converter removed
• Centre exhaust pipe removed or replaced
• Joint dismantled during engine or exhaust repairs
• Previously compressed gasket reused
• Excessive exhaust noise beneath the front of the vehicle

Fitment advice: L315-40-581 is used at the sprung connection between the exhaust manifold/front catalytic-converter assembly and the centre pipe. Confirm that the required component is the cone-profile front sealing ring rather than the separate rear flange gasket.

Replacement advice: Exhaust sealing rings compress and conform to the mating surfaces during installation. A new sealing ring should normally be fitted whenever the joint is separated rather than reusing the previously compressed component.

Joint-condition advice: Inspect both mating surfaces for corrosion, pitting, distortion and remnants of the old seal. A new sealing ring may not correct leakage caused by a cracked pipe, distorted connection or heavily corroded seating surface.

Fastener advice: Inspect both exhaust-joint bolts, compression springs and retaining nuts. Replace components that are heavily corroded, fractured, permanently compressed or have damaged threads.

Other items to consider: Inspect the front catalytic-converter assembly, centre exhaust pipe, oxygen-sensor wiring, exhaust hangers and surrounding heat shields while the joint is accessible.

Useful tools / consumables: Socket and spanner set, penetrating fluid, wire brush, gasket-removal tools, suitable exhaust support and calibrated torque wrench.

Difficulty guide: DIY Difficulty: Moderate. The sealing ring is straightforward to replace once the joint is separated, although exhaust fasteners are commonly affected by heat and corrosion.

Why Genuine Mazda? Genuine Mazda exhaust seals match the original diameter, cone profile, thickness and heat-resistant material specification. Correct dimensions allow the sprung joint to align properly and maintain a reliable gas-tight seal while accommodating exhaust-system movement.

What’s in the box: One Genuine Mazda exhaust manifold-to-mid-pipe sealing ring, part number L315-40-581.

Installation notes: Allow the exhaust system to cool completely and support the centre pipe before releasing the sprung fasteners. Remove the old sealing ring and clean the mating surfaces without damaging their profiles. Position the replacement ring centrally between the exhaust sections, then assemble both bolts, springs and nuts evenly. Tighten each side progressively using the applicable Mazda procedure so the joint remains correctly aligned. Confirm that the exhaust is not placed under tension and check the connection for leakage after installation.