20412308 Hexagon Nut | Genuine Volvo Penta Part

🔧 Product Description

Genuine Volvo Penta hexagon nut used in sets of four on the turbocharger mounting studs of D7 low-mounted turbo installations. It clamps the turbocharger to the exhaust manifold with the specified washers and nut retainers.

🚤 Compatibility

• Engine Family: D, TD, TAD, MD

Full model list at the end of this description.

⚙️ Key Features

• High-temperature turbocharger mounting nut
• Four used with studs 20412314
• Used with washers 20799731 and nut retainers 20505959
• Confirmed with turbocharger 20500295 / exchange 3802178 and related variants
• Tightening procedure must follow the workshop specification
• Engine type: Volvo Penta 7-litre turbocharged industrial diesel
• 4 used per assembly

🔌 Function

Provides the clamp load securing the turbocharger to the exhaust manifold.

⚠️ Common Signs of Failure

• Exhaust leakage or soot at the turbo flange
• Nut loosening under heat cycling
• Damaged or seized threads
• Unable to reach specified torque
• Turbocharger flange movement

🛠️ Service Notes

• Check the stud or bolt thread is clean and undamaged and run the nut down by hand first; grit on the thread gives a false torque reading
• Tighten to the torque in the workshop manual for your engine, following the specified sequence on multi-fastener joints and working round in stages so the load comes up evenly
• Renew self-locking and all-metal locking nuts rather than reusing them — once the locking feature has been through a cycle it no longer holds reliably
• Fit the washer, tab or locking arrangement that belongs with that joint; a locking device that was bent or crimped in service should be replaced, not straightened and reused
• Marine-grade anti-seize on stainless threads reduces galling and makes later removal possible, but keep it off threads that must take a locking compound

🔄 Supersession & Cross Reference

OEM Supersession Chain

• 20412308 → Supersedes 20405609

OEM / Related Numbers

• 20405609 earlier number superseded by this part
• 20412314 - turbocharger mounting studs
• 20799731 - washers
• 20505959 - nut retainers
• 20500295 - related turbocharger
• 3802178 - related turbocharger
• 20405970 - turbocharger gasket

📦 Condition

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

🔎 Full Model Compatibility

Typically suits:

• Volvo Penta D7A-B TA, D7A-T, D7A-TA, D7C-B TA, D7C-TA
• Volvo Penta D5A-B TA, D5A-T, D5A-TA
• Volvo Penta MD2010, MD2010B
• Volvo Penta TAD720GE, TAD720VE
• Volvo Penta TAD721GE, TAD721VE
• Volvo Penta TAD722GE, TAD722VE
• Volvo Penta TAD730GE MECH, TAD730GE EDC4
• Volvo Penta TAD731GE MECH, TAD731GE EDC4
• Volvo Penta TAD750GE, TAD750VE
• Volvo Penta TD720GE, TD720VE PP
• Volvo Penta TAD550GE
• Volvo Penta TAD551GE
• Volvo Penta TAD620VE
• Volvo Penta TAD650VE
• Volvo Penta TAD660VE
• Volvo Penta TAD732GE EDC4
• Volvo Penta TAD733GE EDC4
• Volvo Penta TAD734GE
• Volvo Penta TAD751GE
• Volvo Penta TAD752GE
• Volvo Penta TAD753GE
• Volvo Penta TAD754GE
• Volvo Penta TAD760VE
• Volvo Penta TAD761VE
• Volvo Penta TAD762VE
• Volvo Penta TAD763VE
• Volvo Penta TAD764VE
• Volvo Penta TAD765VE