Genuine Mazda Exhaust Mid-Pipe to Rear Silencer Gasket

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

This gasket seals the flanged connection between the centre exhaust pipe and the rear silencer or back box. It prevents exhaust gases escaping from the joint while allowing the two exhaust sections to be dismantled separately for servicing or replacement.

A correctly sealing exhaust joint is important for maintaining normal exhaust noise levels and preventing hot exhaust gases from escaping beneath the vehicle. A damaged, compressed or incorrectly positioned gasket can cause blowing noises, fumes, soot deposits and exhaust leakage.

One gasket is fitted per vehicle, and this listing supplies one Genuine Mazda gasket. The centre pipe, rear silencer and associated mounting fasteners are supplied separately.

• Part type: Exhaust flange gasket
• Common names: Mid-pipe gasket / back-box gasket / rear-silencer gasket / exhaust pipe seal
• Mazda catalogue description: Gasket, Exhaust System
• Location: Centre exhaust pipe to rear silencer connection
• Function: Seals the flange joint between the mid-pipe and rear exhaust section
• Quantity fitted per vehicle: 1
• Quantity supplied: 1 gasket
• Centre exhaust pipe included: No
• Rear silencer included: No
• Mounting bolts or nuts included: No
• Exhaust hangers included: No
• Brand: Genuine Mazda
• Part No.: PE23-40-305
• Previous Mazda reference: LF45-40-305
• 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 centre-pipe-to-silencer joint
• Visible soot deposits around the flange
• Gasket crushed, split or deteriorated
• Rear silencer or centre pipe removed
• Exhaust sections replaced
• Flange joint disturbed during repair
• Incorrect or reused gasket previously installed
• Excessive exhaust noise beneath the rear of the vehicle

Fitment advice: PE23-40-305 is used at the mid-pipe-to-rear-silencer joint on MX-5 NC models. Confirm that the required gasket is for the rear exhaust flange rather than the separate manifold-to-centre-pipe joint.

Replacement advice: Exhaust flange gaskets compress during installation and should normally be replaced whenever the joint is dismantled. Reusing a previously compressed gasket can result in an incomplete seal.

Flange-condition advice: Inspect both mating flanges for corrosion, distortion, cracking and remnants of the old gasket. A new gasket may not seal correctly against a heavily corroded or warped flange.

Other items to consider: Inspect the exhaust flange bolts, retaining nuts, rear silencer, centre pipe, rubber exhaust hangers and surrounding heat shields. Replace heavily corroded fasteners before final assembly.

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

Difficulty guide: DIY Difficulty: Easy to Moderate. Replacement is straightforward once the exhaust joint is separated, although corroded flange hardware can make dismantling more difficult.

Why Genuine Mazda? Genuine Mazda exhaust gaskets match the original flange diameter, thickness, sealing profile and heat-resistant material specification. Correct dimensions help the exhaust sections align properly and maintain a reliable gas-tight seal.

What’s in the box: One Genuine Mazda exhaust mid-pipe-to-rear-silencer gasket, part number PE23-40-305.

Installation notes: Allow the exhaust system to cool completely and support both exhaust sections before removing the flange fasteners. Separate the joint carefully and remove all remnants of the old gasket without damaging the mating faces. Clean and inspect both flanges, position the new gasket centrally and loosely assemble the fasteners. Align the exhaust system without placing the hangers or pipes under tension, then tighten the flange evenly using the applicable Mazda procedure. Check the joint for leaks after installation.