Rebuild a Yamaha Autolube Oil Pump


As a rule, we try to focus our How-Tos on repairs we think the weekend mechanic can aspire to, so we’ll kick this one off with a qualifying statement: Rebuilding a Yamaha Autolube oil pump requires more than average care and attention.

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Our factory Yamaha manual specifically says of the pump, “Make no attempt to disassemble it,” yet it can be rebuilt. Pump failure is typically due to bad seals or, as we found with our 1974 Yamaha DT125, sludged or stuck parts. In our case the spring for the pump shaft had rusted in the compressed position. A previous owner bypassed the pump in favor of premixing the fuel/oil, likely because the pump couldn’t stroke with a stuck spring.

BikeMasterAs the photo above shows, the Autolube may be a little pump, but it has a surprisingly large number of parts: We counted 39 pieces total, including gaskets. Some of those parts — like the springs and pawls for the pump sprag — are really tiny, and for that reason we strongly suggest taking the pump apart inside a clear plastic bag so parts don’t go flying. If you lose any of the small hard parts, you’ll be looking for a replacement pump. We also strongly suggest taking photos during disassembly to aid assembly.

Yet even with those warnings in mind, a rebuild is doable and in our case netted a perfectly functioning pump. It’s also affordable:’s comprehensive $37.50 kit (see inset photo above) covers all Yamaha oil pumps of this type and includes every seal and gasket you’ll need, plus new pump body screws and new Allen head body mounting bolts, a nice touch. A manual is handy, and bleeding air from the pump before operation is critical.

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1/15/2018 4:15:11 AM

You don't mention the check valve?