Volvo Penta O-Ring – 125017

Volvo Penta O-Ring – Part Number 125017

Brand: Volvo Penta (Genuine OEM)
Part Number: 125017
Official Product Type: O-Ring
Supersedes: No superseded number identified in current references
Replaced By: No replacement listed — 125017 is the current active part number

This is a genuine Volvo Penta OEM O-ring used across multiple Volvo Penta engine and drive system applications. Volvo Penta lists this part as suitable for use in multiple installations, making it a general-purpose sealing O-ring for engine, cooling, fuel, pump, and driveline service points where the parts diagram specifies 125017. Sold individually.

Specifications

• System: Multi-system (engine, cooling, fuel, pump, driveline sealing)
• Type: O-ring (individual sealing component)
• Exact inside diameter, cross-section, and material not published in current catalog. Confirm against your specific engine or drive serial number, original O-ring dimensions, and parts diagram before ordering.

Compatible Applications

This O-ring is used across a wide range of Volvo Penta engine and drive applications. Fitment must be confirmed by engine or drive serial number and by matching the original O-ring location and dimensions:

• Select Volvo Penta AQ-series gasoline engines (where specified by parts diagram)
• Select Volvo Penta 100S / 110S applications (where specified)
• Various Volvo Penta engine, cooling, fuel, pump, and driveline sealing points where 125017 is specified

Serial Number Notice: O-rings vary by inside diameter, cross-section, material, and groove location. Always confirm 125017 against your engine or drive serial number and by direct comparison to the original O-ring before ordering. Do not order by appearance alone.

Alternate & Cross-Reference Part Numbers

• 125017 — Volvo Penta OEM (this part, active number)
• Sierra 18-7178 — Aftermarket cross-reference; verify by application
• GLM 82130 — Aftermarket cross-reference; verify by application
• Mallory 9-76555 — Aftermarket cross-reference; verify by application

When to Replace

Replace this O-ring whenever the related component is disassembled for service, or when the original shows flattening, hardening, cracking, swelling, or signs of seepage. O-rings are one-time-use sealing components — always install a new one during reassembly rather than reusing the original.

Installation Notes

• Compare the new O-ring directly to the original before installation to confirm correct size
• Clean the sealing groove and mating surface before installing the new O-ring
• Apply a light coat of the correct assembly lubricant (compatible with the system fluid) to help prevent twisting or pinching during installation
• Do not reuse the old O-ring
• Follow the Volvo Penta service manual for your specific engine or drive model for the correct assembly procedure and torque specifications

Service Interval

Replace whenever the related component is disassembled — O-rings should not be reused after removal. For components with defined service intervals (water pump, fuel system, cooling system), replace the O-ring at each scheduled service. Refer to the Volvo Penta service manual for your specific engine model and serial number.

Technical FAQ

Can I reuse the old O-ring if it looks undamaged?
No. O-rings compress and deform under service conditions. Even if the original looks intact, it may not reseal reliably after removal. Always install a new O-ring during reassembly.

How do I confirm this is the right O-ring for my application?
The safest method is to match by engine or drive serial number using the Volvo Penta parts diagram, and to compare the new O-ring directly to the original for inside diameter and cross-section before installing. If you’re unsure, have your serial number and the original O-ring dimensions ready before ordering.

Is the Sierra 18-7178 a direct replacement?
Sierra 18-7178 is a commonly listed aftermarket cross-reference for this O-ring. Cross-references should always be verified against the specific application before use, as aftermarket interchange lists can include multiple O-ring sizes under the same reference.

Parts Desk Insights

Small O-rings like this one are easy to overlook during service, but they’re often the reason a freshly serviced component comes back with a seep. Because 125017 is used across a wide range of Volvo Penta applications, the part number alone isn’t always enough — the most reliable check is matching the new O-ring to the original by size before you button everything up. If you’re doing cooling system, fuel system, or pump service on a Volvo Penta engine, it’s worth having a few of these on hand. They’re inexpensive insurance against a repeat job.