Volvo Penta Cooling System Filler Cap 860866 | D3 Series Diesel
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Part Number: 860866
Brand: Volvo Penta (OEM Genuine)
Official Part Name: Filler Cap
Application: Cooling system filler / expansion tank
Genuine Volvo Penta 860866 is an OEM cooling system filler cap used on selected Volvo Penta D3-series marine diesel engines. It seals the coolant filler or expansion tank connection on the applicable cooling circuit. Fitment is confirmed across several D3 100- and 200-series variants — confirm by engine model and serial number before ordering, as filler cap design can vary by tank or engine configuration within the same family.
Compatible Applications
- Volvo Penta D3-110I-G
- Volvo Penta D3-140A-G
- Volvo Penta D3-140I-G
- Volvo Penta D3-150I-G
- Volvo Penta D3-170A-G
- Volvo Penta D3-170I-G
- Volvo Penta D3-200A-G
- Volvo Penta D3-200I-G
- Volvo Penta D3-220A-G
- Volvo Penta D3-220I-G
- Confirm engine model and serial number against the applicable Volvo Penta cooling system diagram before ordering
Engine Family: Volvo Penta D3 series marine diesel
System: Closed-circuit engine cooling — coolant filler / expansion tank
Diagram Position: Coolant filler cap — expansion tank or filler neck connection
Superseded / Alternate Part Numbers
- Current OEM: 860866
- No confirmed Volvo Penta OEM superseding number identified at this time
When to Replace
- Cap is cracked, damaged, or missing
- Cap no longer tightens or seals correctly on the filler neck
- Coolant loss or seepage is traced to the cap or filler connection
- The pressure relief function is no longer operating correctly
- Cap retention or sealing surface is visibly worn or deteriorated
Service Interval
Inspect the filler cap during annual cooling system service or whenever the coolant system is opened. A cap that no longer seals correctly or holds pressure should be replaced immediately — coolant loss from a failed cap can cause overheating under load.
Installation Notes
- Confirm the replacement cap matches the original by part number, engine model, and serial number — filler cap design varies by tank and engine configuration
- Inspect the filler neck sealing surface before installing the new cap
- Do not overtighten — install per the applicable Volvo Penta service procedure
- After installation, check the cooling system for leaks with the engine at operating temperature
Technical FAQ
How do I confirm 860866 fits my D3 engine?
Check the engine model and serial number against the Volvo Penta cooling system parts diagram for your specific D3 variant. The D3 family covers multiple power levels and configurations — matching by part number from the diagram is more reliable than ordering by power rating alone.
Is this cap pressure-rated?
OEM cooling system caps are designed to the pressure specification of the applicable cooling circuit. Always replace with the genuine OEM part number to ensure the correct pressure rating is maintained for your engine's cooling system.
What happens if the cap fails?
A filler cap that no longer seals correctly can allow coolant to escape under operating pressure, leading to coolant loss and potential overheating. If the cap is suspect, replace it before returning the engine to service.
Parts Desk Insights
860866 is most commonly needed when a D3 engine has been overheating or showing unexplained coolant loss and the filler cap is found to be damaged or not sealing properly. It is also frequently requested during routine maintenance when the cap is cracked or the sealing surface has deteriorated. The key issue at the counter: cap design can vary within the D3 family depending on the exact cooling system configuration, so confirming the engine model and serial number before processing the order is important. Worth checking: if the cap has failed due to overpressure, it is worth asking the customer whether the cooling system has been inspected for other causes of elevated pressure before simply replacing the cap.
Related Parts
- Volvo Penta Heat Exchanger / Aftercooler O-Ring 3581070 | D2 D3 Diesel — cooling system O-ring for D3 heat exchanger
- Volvo Penta D3 Seawater Pump V-Ribbed Belt 24677541 — seawater cooling circuit drive belt
- Volvo Penta Heat Exchanger Sealing Strip 860127 | AD31 AD41 TAMD31 TAMD41 KAD42 KAD44 KAD300
- Volvo Penta Thermostat Housing to Heat Exchanger Hose 859800 | MD22 TMD22 TAMD22
- Volvo Penta Water Pump Kit 30751022 — special order
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
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:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
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