Genuine Mazda Standard Crankshaft Main Bearing Set – MX-5 Mk3 / NC • L3Y2-11-SG0

Genuine Mazda L3Y2-11-SG0 Standard Crankshaft Main Bearing Set

Replacement Genuine Mazda standard-size crankshaft main bearing shell set for Mazda MX-5 Mk3, Mk3.5 and Mk3.75 / NC models with applicable 1.8L and 2.0L petrol engines listed in the compatibility table.

The bearing shells fit between the crankshaft main journals, cylinder block and main bearing caps.

They support and accurately locate the crankshaft while allowing it to rotate on a controlled film of pressurised engine oil.

Correct bearing clearance is essential for maintaining engine oil pressure, stable crankshaft alignment and reliable lubrication of the rotating assembly.

Replacement is normally undertaken during an engine rebuild following bearing wear, oil starvation, crankshaft damage, metallic contamination or excessive measured oil clearance.

This listing supplies one complete standard-size Genuine Mazda main bearing shell set for one applicable engine. Crankshaft thrust washers are not included.

• Part type: Crankshaft main bearing shell set
• Mazda catalogue description: Metal set, main bearing
• Alternative descriptions: Main bearing set / crankshaft bearing shells / crankshaft metal set
• Mazda diagram position: 23151
• Primary function: Supports the crankshaft and maintains its specified oil clearance
• System: Engine crankshaft and lubrication system
• Fitting position: Between the crankshaft main journals, cylinder block and main bearing caps
• Primary vehicle application: Mazda MX-5 Mk3, Mk3.5 and Mk3.75 / NC
• Engine applications: Applicable 1.8L L8-family and 2.0L LF-family petrol engines
• Transmission applications: Manual and automatic according to vehicle specification
• Bearing size: Standard size
• Oversize bearing application: No
• Quantity required per engine: One complete set
• Quantity supplied: One complete main bearing shell set
• Crankshaft thrust washers included: No
• Brand: Genuine Mazda
• Part No.: L3Y2-11-SG0
• Also referenced as: L3Y211SG0
• Associated earlier Mazda references: LFY1-11-SG0 and LFY1-11-SG0A

Typical reasons for replacement:

• Engine being fully rebuilt
• Main bearing shells worn, scored or damaged
• Excessive measured crankshaft oil clearance
• Low engine oil pressure caused by bearing wear
• Crankshaft knocking or rumbling diagnosis
• Oil starvation or lubrication-system failure
• Metallic debris found in the engine oil or sump
• Crankshaft removed for inspection or repair
• Cylinder block or main bearing caps being replaced

Fitment advice: This is the standard-size main bearing set used on applicable Mazda MX-5 NC 1.8L and 2.0L MZR-family engines.

Bearing-size advice: Do not select bearing size solely from the part description or the bearings removed from the engine. Measure the crankshaft main journals and cylinder-block bearing housings using calibrated equipment and compare the results with the applicable Mazda specifications.

Oversize advice: L3Y2-11-SG0 is the standard-size set. Mazda reference L3Y2-11-SH0 is separately catalogued as a 0.25 mm oversize bearing set. Oversize shells are only suitable where the crankshaft has been correctly machined to the corresponding undersize journal specification.

Clearance advice: Confirm the oil clearance at every main journal using precision measurement equipment or an approved bearing-clearance gauge. Incorrect clearance can cause low oil pressure, bearing seizure, noise or rapid engine damage.

Crankshaft advice: Inspect each main journal for scoring, taper, ovality, heat discolouration and cracking. A damaged or incorrectly sized crankshaft must be repaired or replaced before new bearings are installed.

Block and cap advice: Main bearing caps are position- and orientation-specific. Keep each cap in its original location and inspect the block and cap housing bores for distortion, fretting or damage.

Thrust-washer advice: The crankshaft thrust washers are separate components and are not included with this main bearing set. Inspect and measure crankshaft end float during assembly and replace the thrust components where required.

Oil-hole advice: Ensure all bearing-shell oil holes and grooves align correctly with the cylinder-block oil passages. Incorrect shell positioning can interrupt lubrication and cause immediate bearing failure.

Cleaning advice: Thoroughly clean the crankshaft, bearing housings and oil passages before assembly. Even small particles trapped beneath a shell can distort the bearing and reduce its running clearance.

Lubrication advice: Apply suitable engine assembly lubricant or clean engine oil to the bearing running surfaces during assembly. Keep the rear surfaces of the shells and their housing seats clean and dry unless the Mazda procedure states otherwise.

Fastener advice: Follow the applicable Mazda tightening sequence, torque values and angle-tightening procedure for the main bearing cap fasteners. Replace any torque-to-yield or single-use bolts where specified.

Oil-system advice: Where bearing damage resulted from oil starvation or contamination, inspect the oil pump, oil-pump drive chain, pickup strainer, oil galleries, pressure-control components and oil cooler before rebuilding the engine.

Priming advice: Prime the engine lubrication system before initial start-up. Confirm that oil pressure is established promptly and stop the engine immediately if the oil-pressure warning remains illuminated or abnormal noise is present.

Other items to consider: Consider inspecting or replacing the crankshaft thrust washers, connecting-rod bearings, oil pump, oil-pump chain, front and rear crankshaft seals, main bearing fasteners, engine oil and oil filter according to their measured condition.

Useful tools / consumables: Engine stand, calibrated micrometers, bore gauge, bearing-clearance gauge, torque wrench, angle gauge, assembly lubricant, lint-free cleaning materials and suitable engine oil.

Difficulty guide: DIY Difficulty: Specialist / engine-rebuild level. Installation requires complete access to the crankshaft, precision dimensional measurement and strict adherence to the Mazda engine-assembly procedure.

Why Genuine Mazda? Genuine Mazda main bearing shells are manufactured to the intended dimensions, material specification, oil-groove arrangement and crankshaft-clearance requirements of the original engine. Using the correct OE bearing set helps retain the designed crankshaft support and lubrication characteristics.

What’s in the box: One Genuine Mazda standard-size crankshaft main bearing shell set for one engine, part number L3Y2-11-SG0. Crankshaft thrust washers, connecting-rod bearings, crankshaft, seals, fasteners, oil and assembly tools are not included unless specifically shown or stated separately.

Installation notes: Completely dismantle the applicable lower engine assembly in accordance with the Mazda workshop procedure. Measure the crankshaft journals and bearing housings before selecting the bearing size. Clean all components and oil passages, install each shell in its correct position and confirm oil-hole alignment. Measure the finished oil clearance and crankshaft end float, lubricate the running surfaces, then tighten the main bearing caps in the specified sequence. Confirm that the crankshaft rotates smoothly before continuing the engine build and prime the lubrication system before initial start-up.