20405804 Tensioner | Genuine Volvo Penta Part

🔧 Product Description

Genuine Volvo Penta early-production alternator belt tensioner for TD520GE and TD720GE 14 V 55 A and 28 V 35 A charging systems. Later engine arrangements use a different tensioner and locking-strap design.

🚤 Compatibility

• Engine Family: D, TD, TAD, MD

Full model list at the end of this description.

⚙️ Key Features

• Mechanical alternator belt tensioner
• Early production version
• Used with bushing 20405803 and washers 20405802
• Confirmed on TD520GE and TD720GE alternator systems
• Maintains the specified V-belt tension
• Engine type: Volvo Penta 5- and 7-litre industrial diesel

🔌 Function

Applies and maintains tension on the alternator drive belt.

⚠️ Common Signs of Failure

• Belt squeal or low charging output
• Tensioner pivot seizure
• Excessive tensioner play
• Repeated belt loosening
• Uneven belt wear

🛠️ Service Notes

• Renew the tensioner and the belt together, and while the belt is off check the other pulleys for wear, roughness in the bearing and any wobble
• Note the belt routing and the tensioner's mounting position and stops before removing the old unit, and check the new one carries the same pulley and offset
• Locate the tensioner properly on its dowel or stop and tighten it to the workshop manual figures — a tensioner not sitting square will run the belt off line and destroy it
• Wind the tensioner back with the correct tool or square drive, fit the belt over the pulleys by hand and release the tensioner onto it; never lever a belt on with a screwdriver and never use the tensioner arm as a pry bar
• Check every rib or tooth is seated in its groove, turn the engine over by hand, then run it up and recheck belt run and tension after the first period of running, following the procedure for your engine

🔄 Supersession & Cross Reference

OEM Supersession Chain

• 20405804 → Supersedes 20430776

OEM / Related Numbers

• 20555348 earlier number superseded by this part
• 20430776 earlier number superseded by this part
• 20405803 - pivot bushing
• 20405802 - washers
• 20405917 - flange screw
• 20797044 - later lock strap

📦 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 TAD520GE, TAD520VE
• Volvo Penta TAD720GE, TAD720VE
• Volvo Penta TAD721GE, TAD721VE
• Volvo Penta TAD722GE, TAD722VE
• Volvo Penta TAD550GE
• Volvo Penta TAD551GE
• Volvo Penta TAD750GE
• Volvo Penta TAD751GE
• Volvo Penta TD520GE
• Volvo Penta TD720GE