Genuine Mazda Camshaft Pulley Locking Bolt & Washer • LF17-12-428

Genuine Mazda LF17-12-428 Camshaft Pulley Locking Bolt & Washer

Replacement Genuine Mazda camshaft pulley locking bolt and washer for Mazda MX-5 Mk3, Mk3.5 and Mk3.75 / NC models fitted with the 1.8L L8-DE or 2.0L LF-VE petrol engine from 2005/2006 to 2015 listed in the compatibility table.

The bolt secures the camshaft pulley or timing sprocket to the end of the camshaft. It provides the clamping force required to retain the pulley correctly while the timing chain transfers rotation from the crankshaft to the engine's camshafts.

Secure camshaft-pulley fastening is critical to maintaining the intended valve timing. A loose, damaged or incorrectly tightened bolt can allow pulley movement and may lead to incorrect timing or serious internal engine damage.

This listing supplies one Genuine Mazda camshaft pulley locking bolt with its associated washer. One bolt is required for each applicable camshaft pulley position. Inspect both pulley fixings during timing-chain, camshaft or cylinder-head work.

Replacement should be considered where the original bolt has damaged or contaminated threads, a rounded head, corrosion, visible stretching or damage caused during removal. Replacement may also be appropriate during a major engine rebuild where critical timing fasteners are being renewed.

• Part type: Camshaft pulley locking bolt and washer
• Primary use: Secures the camshaft pulley / timing sprocket to the camshaft
• System: Engine valvetrain and timing-chain drive
• Location: Camshaft pulley at the front of the cylinder head
• Vehicle application: Mazda MX-5 Mk3, Mk3.5 and Mk3.75 / NC
• Engine applications: 1.8L L8-DE and 2.0L LF-VE
• Transmission applications: Manual and automatic according to vehicle specification
• Quantity required: One per applicable camshaft pulley position
• Quantity supplied: One bolt-and-washer assembly
• Brand: Genuine Mazda
• Part No.: LF17-12-428
• Also referenced as: LF1712428
• Associated camshaft pulley: LF01-12-425

Fitment advice: Confirm that the engine retains the original Mazda camshaft and pulley arrangement. Compare the bolt length, thread, head profile and washer arrangement with the removed fastener before installation. This is a critical timing-system fastener and must be installed using the applicable Mazda tightening procedure.

Other items to consider: When changing this part, you may also want to consider purchasing the camshaft pulley, timing chain, chain guides, chain tensioner, variable valve timing actuator where applicable, camshaft oil seals, front timing-cover seals and Mazda-specified engine sealant.

Useful tools / consumables: Mazda-compatible camshaft and crankshaft timing tools, camshaft-pulley holding tool, suitable sockets, breaker bar, calibrated torque wrench, angle gauge where required, clean engine oil and thread cleaner.

Difficulty guide: DIY Difficulty: Advanced. Access normally requires dismantling of the engine timing area. The camshafts and crankshaft must be held in their correct positions, and the pulley must be restrained without placing excessive load on the timing tools or camshaft.

Why Genuine Mazda? Genuine Mazda engine fasteners are manufactured to the intended thread specification, dimensions, strength and clamping requirements. Using the correct OE camshaft-pulley bolt helps maintain secure pulley retention and compatibility with the original Mazda camshaft and timing components.

What’s in the box: One Genuine Mazda camshaft pulley locking bolt and washer assembly, part number LF17-12-428. The camshaft pulley, timing chain, timing tools and other engine components are not included unless specifically shown or stated separately.

Installation notes: Position and lock the crankshaft and camshafts using the correct engine-timing procedure before loosening or tightening the pulley bolt. Clean and inspect the camshaft thread and pulley mounting surfaces. Do not use the timing-position tools alone to resist the full tightening load; restrain the pulley using the appropriate holding method. Tighten the fastener to the applicable Mazda torque and angle specification, then confirm the engine timing before reassembly and start-up.