21539423 Rocker Arm Shaft | Genuine Volvo Penta Part

🔧 Product Description

A precision rocker arm shaft used in the cylinder-head valve mechanism of the Volvo Penta D9A2L MH marine engine. It supports the intake, exhaust and injector rocker arms and supplies their lubricating oil.

🚤 Compatibility

Typically suits:

• Volvo Penta D11C1-A MP
• Volvo Penta D11C3-A MP
• Volvo Penta D11C2-A MP
• Volvo Penta D11C4-A MP
• Volvo Penta TAD1180-83VE
• Volvo Penta D11B3-A MP
• Volvo Penta D11B4-A MP
• Volvo Penta D11B2-A MP
• Volvo Penta D11B1-A MP
• Volvo Penta D9A2L MH
• Volvo Penta D9A2M MP
• Volvo Penta TAD1170-72VE
• Volvo Penta TAD1150-52VE
• Volvo Penta TAD1140-42VE

• Engine Family: D, TAD

⚙️ Key Features

• Genuine Volvo Penta D9 rocker arm shaft
• Internal rocker-lubrication passages
• Precision-ground pivot surfaces
• Supports the complete valve and injector rocker assembly
• Uses two expansion plugs 955096
• Engine type: 9.4 L inline-six turbocharged marine diesel

🔌 Function

Provides the pivot axis and lubricating-oil distribution path for the valve and injector rocker arms.

⚠️ Common Signs of Failure

• Excessive rocker-arm clearance
• Scored or worn shaft journals
• Restricted oil delivery to the rockers
• Uneven valve or injector operation

🛠️ Service Notes

• Check the shaft and the rocker bushes for wear, scoring and ovality and measure them against the figures in the manual for your engine — a worn shaft will ruin new rockers
• Make sure the oil feed holes in the shaft are clear and face the way the procedure for your engine specifies, and that the supply drilling in the head or pedestal is clear; a blocked or misaligned feed starves the whole rocker gear
• Rebuild the shaft in its original order and orientation, keeping rockers, spacers, springs and pedestals in the positions they came from
• Coat the shaft and bushes with clean engine oil before assembly and turn the assembly by hand to confirm every rocker moves freely
• Tighten the pedestals down evenly and in stages so the shaft is not pulled out of straight, then set the valve clearances by the procedure for your engine and prime the valve gear with oil before starting

🔄 Supersession & Cross Reference

OEM Supersession Chain

• 21539423 → Supersedes 20715792

OEM / Related Numbers

• 20715792 earlier number superseded by this part
• 955096 - expansion plug, two used
• 21881494 - intake rocker arm
• 21881195 and 21808975 - fuel-injector rocker references
• 21949471 - exhaust rocker arm
• 20751464 - valve caliper
• 21792303 - leaf spring
• 3964817 - lubricating jet

📦 Condition

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