Yamada 640016 O-Ring 17.6 mm x 2.4 mm, Buna-N for G25 Series
The Yamada 640016 is the factory o-ring specified for G25 Series pumps. It seals one of the joints inside the pump, and because it costs almost nothing next to the downtime a leak causes, it is the kind of part worth replacing on sight rather than on schedule.
The reason to replace these on sight is that a seal which looks serviceable often is not. Compression set leaves a flattened, glossy band where the ring sat, and a ring in that condition will seal a dry bench test and then leak the moment the pump sees pressure and vibration. Nicks from a screwdriver used to lever the old ring out are the other common cause, and they are invisible until the joint is back together and under load.
Key Features
- Genuine Yamada replacement o-ring
- Material: Buna-N (NBR), 70 durometer
- Nominal size: 17.6 mm x 2.4 mm
- Fits G25 Series pumps
- 4 per pump in the assemblies that use it
- Restores a positive seal at the joint without machining or adjustment
Applications
- G25 Series pumps
- Scheduled rebuilds and seal kit top-ups
- Chasing a weep at a joint face after reassembly
- Replacing a ring that has taken a compression set
- Service after a fluid change that attacked the old elastomer
- Marine, industrial and transfer duty
Specifications
- Brand: Yamada
- Manufacturer: Yamada America
- Manufacturer Part Number: 640016
- Part Type: O-Ring
- Material: Buna-N (NBR), 70 durometer
- Nominal Size: 17.6 mm x 2.4 mm
- Fits: G25 Series pumps
- Quantity Used: 4 per pump
- Condition: New
Frequently Asked Questions
Q: Is a sleeve O-ring different from a body O-ring?
Functionally it is the same static seal, but the ones on the air valve sleeve see constant reversing pressure and a lot of cycles, so they are usually the first to go and are worth replacing whenever the air valve is stripped.
Q: Can I reuse the old O-ring if it looks fine?
It is a false economy. A ring that has been compressed for months has taken a set in the shape of its groove and no longer springs back against the sealing faces. It will often pass a dry test and then weep once the pump is running under pressure.
Q: How do I stop damaging the new ring during assembly?
Use a plastic or brass pick to remove the old one, clean the groove so no grit is trapped under the new ring, and lubricate it lightly with something compatible with the fluid before closing the joint. Most premature failures are assembly damage, not material failure.
Q: Does the durometer number matter?
Yes. Hardness sets how far the ring deflects under a given squeeze. A softer ring in a groove designed for a harder one extrudes into the gap and nibbles away at the edge; a harder one in a soft ring groove may not fill the groove at all.
Not sure this is the right part? Send us a Picture of the Pump Plate on your pump and the CLR Marine team will confirm the correct o-ring.
CLRMarine
