990978 Lock Nut | Genuine Volvo Penta Part

🔧 Product Description

Genuine Volvo Penta M6 lock nut weighing 0.003 kg and listed for 33 applications across the D, TAD, TWD, VMM and MD ranges.

🚤 Compatibility

• Engine Family: D, TAD, TWD, VMM, MD
• HP Range: 300-480 HP

Full model list at the end of this description.

⚙️ Key Features

• M6
• 0.003 kg
• 33 applications across five ranges
• Quantity varies by assembly, most commonly four

🔌 Function

Holds an M6 threaded joint against vibration, the locking feature resisting the nut turning back.

⚠️ Common Signs of Failure

• Nut loose or missing at service
• Locking action gone - the nut turns down by hand
• Thread crossed or stripped
• Rust between nut and stud

🛠️ Service Notes

• M5 lock nut 990977 is the smaller thread listed in this group - match the nut to the stud rather than to the weight
• Use a new nut each time the joint is opened

📦 Condition

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

🔎 Full Model Compatibility

Typically suits:

• Volvo Penta D8A5-A MH, D8A6-A MH, D8A5-A MG, D8A6-A MG, D8A4-A MP, D8A1-A MP, D8A2-A MP, D8A3-A MP
• Volvo Penta D6-340I-G, D6-380I-G, D6-440I-G, D6-480I-G, D6-440I-WJ-G, D6-300I-G
• Volvo Penta D5A-B TA, D5A-T, D5A-TA
• Volvo Penta D7A-B TA, D7A-T, D7A-TA
• Volvo Penta MD2010, MD2010B
• Volvo Penta D9A2A
• Volvo Penta TAD1630P
• Volvo Penta TAD940VE
• Volvo Penta TAD941VE
• Volvo Penta TAD942VE
• Volvo Penta TAD943VE
• Volvo Penta TAD950VE
• Volvo Penta TAD951VE
• Volvo Penta TAD952VE
• Volvo Penta TWD1683VE
• Volvo Penta VMM-A