21246161 Main Bearing | Genuine Volvo Penta Part

🔧 Product Description

Genuine crankshaft main bearing intended for engines with crankshaft main journals reconditioned to the first undersize specification. The 0.25mm undersize bearing restores the correct running clearance and oil film between the crankshaft and cylinder block.

🚤 Compatibility

Typically suits:

• Volvo Penta MD2010B
• Volvo Penta MD2010-C
• Volvo Penta MD2010-D
• Volvo Penta MD2020B
• Volvo Penta MD2020-C
• Volvo Penta MD2020-D

• Engine Family: MD

⚙️ Key Features

• Genuine Volvo Penta main bearing
• 0.25mm undersize specification
• Intended for correctly machined crankshaft journals
• Restores specified crankshaft support and oil clearance
• Must be installed in the correct bearing position and orientation

🔌 Function

The bearing supports the crankshaft while maintaining a controlled lubricating-oil film between the crankshaft journal and engine block.

⚠️ Common Signs of Failure

• Deep knocking from the crankcase
• Excessive crankshaft end or radial movement
• Metallic material in the lubricating oil
• Scored or heat-discoloured bearing surfaces
• Excessive measured bearing clearance

🛠️ Service Notes

• Replace main bearings as a complete set and never mix new shells with used ones; check that the grade or size supplied matches the crankshaft, which may have been reground
• Fit the shells with dry backs — shell backs and housings must be clean, dry and free of oil, grease and debris so the shell beds fully onto the housing and can carry heat away
• Make sure each shell's locating tang sits in its recess and that the shell is flush with the housing face rather than standing proud
• Never scrape, file, polish or dress a bearing shell and keep abrasives away from it; check the running clearance against the figures in the workshop manual for your engine using a crush-type clearance gauge
• Lubricate the running surfaces with clean engine oil, refit each cap in its original position and direction, tighten in the stages the manual gives, then turn the crankshaft by hand to confirm it is free

🔄 Supersession & Cross Reference

OEM Supersession Chain

• 21246161 → Supersedes 861810

OEM / Related Numbers

• 861810 earlier number superseded by this part

📦 Condition

• Genuine Volvo Penta part
• Brand new
• Supplied in original or equivalent packaging