Description
The Yanmar 129574-55780 is the genuine OEM O-ring that seals the sensor into the fuel filter housing on Yanmar 4JH4 series marine diesel engines. It is listed in the Yanmar parts catalogue as part of the fuel filter assembly that uses filter 129574-55711.
Small part, real consequences
This is a low value item that causes problems out of all proportion to its price. The seal it makes is on the suction side of the fuel system, so when it hardens or takes a set it does not usually drip where you can see it. Instead it lets air into the fuel, and you get an engine that runs rough, hunts, is hard to start, or dies under load, while everything looks dry from the outside. People chase that fault for a long time before they think of the O-ring.
Replace it with the filter
Fit a new one whenever the sensor is disturbed. Because the part costs so little relative to the time involved in getting to it, keep one or two aboard with your spare filters rather than ordering one when you need it.
Check your fitment
The engine models listed in the product specifications are a guide only. Always confirm against the parts catalogue for your engine’s model and serial number before ordering. If you are unsure, send us your engine plate details and we will check it for you.
Genuine Yanmar parts
We stock genuine Yanmar OEM parts, not pattern copies. If you need help identifying the right part for your engine, or want to book a service, get in touch.
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