Volvo Penta D3 Timing Belt 30777779 | OEM Toothed Drive Belt
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Part Information
- Part Number: 30777779
- Brand: Volvo Penta
- Official Product Type: Toothed Timing Belt — Engine Timing System
- Supersedes: 31258306 (related service reference)
- Replaced By: No current supersession on record
- Diagram Position: Timing Gear Housing — alongside timing belt 31359568, tensioner 31339542, idler pulley 8692561, and belt protectors
Overview
The Volvo Penta 30777779 is a genuine OEM toothed timing belt for Volvo Penta D3 marine diesel engines. It is one of two toothed belts used in the D3 timing gear housing and is responsible for synchronizing engine timing across the full D3 production range from generation A through H. Because this is a positive-drive timing belt — not an accessory or serpentine belt — its condition is directly tied to accurate valve timing and engine reliability. Replacing it at the correct service interval is one of the most important scheduled maintenance tasks on the D3 engine.
Compatible Applications
- Volvo Penta D3-110I (generations A–H)
- Volvo Penta D3-130A / D3-130I
- Volvo Penta D3-140A / D3-140I
- Volvo Penta D3-150I
- Volvo Penta D3-160A / D3-160I
- Volvo Penta D3-170A / D3-170I
- Volvo Penta D3-190A / D3-190I
- Volvo Penta D3-200A / D3-200I
- Volvo Penta D3-220A / D3-220I
Coverage spans D3 generations A through H depending on horsepower and installation type. Always confirm your complete engine model, generation suffix, and serial number against the Volvo Penta timing gear housing diagram before ordering.
Serial Number Requirements
The D3 timing system uses two separate toothed belts (30777779 and 31359568) in the same housing. Confirm the exact belt position from your engine parts diagram and verify by engine model and serial number before ordering to ensure you receive the correct belt for your application.
System
Timing System — Engine Timing Gear Housing / Valve Train Drive
Service Interval
Replace at the Volvo Penta scheduled timing belt service interval for your D3 engine, or sooner if inspection reveals any of the following:
- Cracking or tooth deterioration
- Frayed or worn belt edges
- Oil or coolant contamination
- Abnormal wear patterns
- Damage caused by a failed tensioner or idler pulley
Refer to the applicable Volvo Penta D3 service documentation for the specific interval for your engine generation.
Related Parts — D3 Timing System
The following components are part of the D3 timing gear housing and should be inspected or replaced at the same time:
- Timing Belt — 31359568 (second toothed belt in the same housing)
- Tensioner — 31339542
- Idler Pulley — 8692561
- Front Belt Protector — 30757900
- Rear Belt Protector — 30757901
- Lower Belt Protector — 31293007
Dimensions & Weight
- Weight: Approximately 0.6 kg
- Belt dimensions per Volvo Penta D3 timing gear housing specification — confirm via parts diagram for your engine generation
Technical FAQ
Q: Is 30777779 the same as 31258306?
A: 31258306 appears as a related service reference for this belt in D3 documentation. Always order by the current active OEM number (30777779) to ensure you receive the correct part.
Q: What is the difference between 30777779 and 31359568?
A: Both are toothed timing belts used in the D3 timing gear housing, but they are separate parts at different positions. Confirm which belt position you need from the Volvo Penta timing gear housing diagram for your engine before ordering.
Q: Should I replace the tensioner and idler pulley at the same time?
A: Yes — Volvo Penta recommends inspecting and typically replacing the tensioner (31339542) and idler pulley (8692561) during timing belt service. Replacing the belt in a worn tensioner or pulley significantly shortens belt life and risks premature failure.
Q: Is this a timing belt or an accessory belt?
A: This is a toothed positive-drive timing belt — it drives the engine valve train and is critical to engine timing. It is not an accessory or serpentine belt.
Parts Desk Insights
The most common confusion with this part is customers mixing it up with 31359568, the other toothed belt in the same D3 timing housing. Both are genuine OEM timing belts, but they are position-specific and not interchangeable — the diagram is the only reliable way to confirm which one is needed. It’s also worth noting that the existing description included aftermarket cross-references (Gates, Continental, Bosch, Dayco) — these have been removed since this is an OEM-only listing. When a customer is doing timing belt service, it’s a good opportunity to recommend the tensioner and idler pulley at the same time — the labor is already done and the cost of those parts is small compared to a repeat job.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
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If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
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