11978 Washer | Genuine Volvo Penta Part

🔧 Product Description

A genuine Volvo Penta flat retaining washer used in selected heat-exchanger, coolant-pipe, oil-pump and engine hardware assemblies. Its exact location varies by engine family, so the component and fastener position determine fitment. On TAMD61A and TAMD71B cooling systems the washer is used with the heat-exchanger fastening arrangement. The same service number also appears in later D4 / D6 and industrial engine assemblies.

🚤 Compatibility

• Engine Family: TAMD, D, AD, TWD, TMD, THD, TD, DH, TAD
• HP Range: 180-435 HP
• Year Range: Approximately 1970s - 2010s

Full model list at the end of this description.

⚙️ Key Features

• OEM Volvo Penta part number 11978
• Net weight 0.018 kg (approximately 18 g)
• Supplied as an individual washer
• Fits D4 and D6 common-rail marine diesel engines, along with AD31/AD41, TAMD61/71/72, TMD/THD102, TD/TWD 1000-series and DH10A engine families
• Genuine Volvo Penta component for correct fit and torque retention
• Engine type: Volvo Penta 4- and 6-cylinder marine / industrial diesel

🔌 Function

The washer distributes the clamping force of a bolt or nut over a wider area and protects the component surface from damage during tightening. Depending on the assembly, it also helps maintain joint tension and prevents the fastener from loosening in service.

⚠️ Common Signs of Failure

• Visible corrosion, pitting or scaling on the washer face
• Distortion, dishing or cracking from over-torquing
• Fasteners repeatedly working loose or losing torque
• Fretting marks or scoring on the mating surface
• Seepage or weeping at the joint where the washer forms part of the seal

🛠️ Service Notes

• Check you are fitting the same type of washer that came out — plain, hardened, sealing and locking washers are not interchangeable, and the wrong one either fails to seal or fails to hold
• Treat sealing washers on fuel, oil and coolant unions as single-use; they seal by deforming onto the faces, so a used one will not seal reliably a second time
• Clean the seating faces and make sure the washer sits flat and square, fully under the head or nut, before tightening — a washer trapped on a chamfer or edge will crush unevenly
• Tighten the fastener to the figure given in the workshop manual for your engine, and account for every washer on reassembly so none is left loose inside a housing or the engine bay

🔄 Supersession & Cross Reference

OEM / Related Numbers

• 847580 related TAMD61A heat exchanger
• 864916 related heat exchanger
• 471709 related connecting pipe
• 11978 formatted supplier reference VOL11978

📦 Condition

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

🔎 Full Model Compatibility

Typically suits:

• Volvo Penta D6-370A-C, D6-350A-A, D6-350A-B, D6-330A-D, D6-330D-E, D6-370D-E, D6-370D-B, D6-330D-B, D6-330A-F, D6-370A-F, D6-370D-A, D6-330D-C, D6-330A-C, D6-370D-C, D6-330D-D, D6-370D-D, D6-330D-F, D6-370A-D, D6-330A-E, D6-370A-E, D6-370D-F, D6-330I-D, D6-310I-B, D6-280I-B, D6-280I-E, D6-280I-D, D6-310I-D, D6-435I-D, D6-310I-E, D6-280I-A, D6-310I-A, D6-300A-F, D6-300D-F, D6-300I-F, D6-310D-A, D6-310D-B, D6-310D-D, D6-310D-C, D6-310D-E, D6-370I-A, D6-370I-B, D6-330I-B, D6-330I-C, D6-370I-C, D6-310A-B, D6-280A-C, D6-310A-C, D6-310A-A, D6-280A-D, D6-310A-D, D6-280A-E, D6-310A-E, D6-280I-C, D6-310I-C, D6-280A-A, D6-280A-B, D6-330I-F, D6-370I-F, D6-400A-E, D6-435D-A, D6-435D-D, D6-435D-E, D6-435D-F, D6-435I-A, D6-435I-C, D6-435I-E, D6-400A-F, D6-435D-C, D6-435I-F, D6-370I-D, D6-330I-E, D6-370I-E, D6-330A-B, D6-370A-B
• Volvo Penta D4-260A-B, D4-260A-A, D4-260A-C, D4-260A-D, D4-260A-E, D4-260A-F, D4-260D-B, D4-260D-C, D4-260D-D, D4-260D-E, D4-260D-F, D4-260I-A, D4-260I-B, D4-260I-C, D4-260I-D, D4-260I-E, D4-260I-F, D4-300A-A, D4-300A-C, D4-300A-D, D4-300A-E, D4-300A-F, D4-300D-A, D4-300D-C, D4-300D-D, D4-300D-E, D4-300D-F, D4-300I-A, D4-180I-C, D4-225I-C, D4-180I-D, D4-225I-D, D4-180I-E, D4-225I-E, D4-180I-F, D4-225I-F, D4-210A-A, D4-210A-B, D4-225A-B, D4-225A-C, D4-225A-D, D4-300I-C, D4-300I-D, D4-300I-E, D4-300I-F, D4-225A-E, D4-225A-F, D4-210I-A, D4-210I-B, D4-180I-B, D4-225I-B
• Volvo Penta DH10A, DH10A 285, DH10A 360, DH10A Rail
• Volvo Penta 2003TB, 2003T, 2003TR
• Volvo Penta TAMD72A, TAMD72P-A, TAMD72WJ-A
• Volvo Penta THD102KB, THD102KD, THD102K-KB
• Volvo Penta AD31, AD31B
• Volvo Penta AD41B, AD41A
• Volvo Penta TAD1030V, TAD1030VE
• Volvo Penta TAMD71B, TAMD71A
• Volvo Penta D41B
• Volvo Penta TAMD61A
• Volvo Penta TAMD62A
• Volvo Penta TD100G
• Volvo Penta TD1010G
• Volvo Penta TD1030VE
• Volvo Penta TD30A
• Volvo Penta TMD102A
• Volvo Penta TWD1010G
• Volvo Penta TWD1030ME
• Volvo Penta TWD1031VE