21860003 Idler Gear | Genuine Volvo Penta Part

🔧 Product Description

A genuine timing-gear idler used in the engine gear train on Volvo Penta D8 and selected TAD5 engines. It transfers rotation between the crankshaft, camshaft and auxiliary gears.

🚤 Compatibility

• Engine Family: TAD, D, TADH
• HP Range: Approximately 225-650 HP
• Year Range: Approximately 2010 - current supported applications

Full model list at the end of this description.

⚙️ Key Features

• Timing-gear idler for the engine gear train
• 0.581 kg
• Listed for 26 applications across the TAD, D and TADH ranges
• Transfers rotation between the crankshaft, camshaft and auxiliary gears

🔌 Function

Sits between the driving and driven gears in the timing train, passing rotation across the gap and holding the timing relationship between crankshaft, camshaft and the auxiliary drives.

⚠️ Common Signs of Failure

• Whine or growl from the timing end that rises with engine speed
• Rattle at idle that quietens as revs come up
• Metallic glitter in the oil or on the drain plug
• Teeth pitted, chipped or with a wear step across the face on strip-down
• Bearing or bush worn, giving perceptible rock on the shaft

🛠️ Service Notes

• Idler gear 21860076 is the heavier gear in the same train at 1.844 kg - check which position is being replaced before ordering
• Inspect the mating gears and the idler shaft at the same time; a failed idler leaves its wear pattern on both
• Renew the bush or bearing hardware with the gear where the assembly is built that way

🔄 Supersession & Cross Reference

OEM / Related Numbers

• 21736275 - idler-gear hub
• 976042 - O-ring
• 21736279 - retaining plate
• 964106 - gasket
• 21735434 - related drive gear

📦 Condition

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

🔎 Full Model Compatibility

Typically suits:

• Volvo Penta D8A2-A MP, D8A5-A MH, D8A6-A MH, D8A5-A MG, D8A6-A MG, D8A4-A MP, D8A1-A MP, D8A3-A MP
• Volvo Penta TAD840GE, TAD840-43VE, TAD840GE-B
• Volvo Penta TAD570-72VE, TAD570-71VE-B
• Volvo Penta TAD880-82GE, TAD880-84VE
• Volvo Penta TADH880-82GE, TADH880-84VE
• Volvo Penta TAD540-42VE
• Volvo Penta TAD550-51VE
• Volvo Penta TAD552VE
• Volvo Penta TAD580-83VE
• Volvo Penta TAD841-43GE
• Volvo Penta TAD850-52VE
• Volvo Penta TAD851-53GE
• Volvo Penta TAD853VE
• Volvo Penta TAD870-73VE