How To Repair Oil Pump

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

Our factory Yamaha manual specifically says of the pump, "Make no attempt to detach it," still information technology tin be rebuilt. Pump failure is typically due to bad seals or, as nosotros 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.

As the photo above shows, the Autolube may be a little pump, simply 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 propose taking the pump apart within a clear plastic bag and so parts don't go flying. If you lose whatever of the small difficult parts, you'll exist looking for a replacement pump. Nosotros also strongly suggest taking photos during disassembly to aid assembly.

Yet even with those warnings in mind, a rebuild is doable and in our example netted a perfectly functioning pump. Information technology'due south also affordable: HVCcycle.cyberspace'south comprehensive $37.fifty kit (see inset photo above) covers all Yamaha oil pumps of this type and includes every seal and gasket yous'll need, plus new pump body screws and new Allen caput body mounting bolts, a nice touch. A transmission is handy, and haemorrhage air from the pump before operation is critical.

1. The oil pump is under the right forepart cover. Remove the cover, noting the oil throttle cablevision that pulls on the pump. Rotate the pulley to slacken the cable. Disconnect the cable from the pulley, then disconnect the oil feed lines. Remove the two Phillips head screws securing the pump.

ii. With the pump removed from the engine, remove the modest cotter pin securing the manual oil starter plate, followed by the plate itself. The plate might be stuck to the shaft. If it is, spray information technology with penetrant and carefully work it off to avert accidentally breaking the plate.

3. Next, turn the pump over and loosen the 9mm nut securing the cable pulley to the oil pump plunger shaft. Hold the caster against the pump body, then remove the nut, wave washer, adjustment plate and any shims nether the aligning plate. Keep the shims rubber; they're crucial to pump scale.

4. Remove roll pin that keys the caster, followed by the caster and its spring, noting the tabs on the jump to locate information technology in the oil pump body and to the pulley.

five. Remove the four Phillips head screws securing the oil pump plunger embrace to the oil pump body.

6. Split up the oil pump plunger from the torso. In hindsight, we would have been wise to practice this working within a clear plastic pocketbook to avoid losing small parts. We were lucky and didn't.

7. Removing the large flat washer exposes the worm bulldoze gear. Note the small pins keying information technology to the oil pump plunger cam. They're spring-loaded and can fly off if removing the gear. Instead, working inside a plastic pocketbook, remove the plunger cam complete with the gear and pins, holding it together and pushing it up through the pump torso.

8. The plunger cam coming out with the gear and pins removed. Note the 2 washers on the stem. A apartment washer goes against the pump body and a wave washer against the bottom of the plunger cam.

nine. The plunger cam has a small-scale oil seal inside its shaft for the pump plunger. Using a small hooked tool, reach in and remove the seal.

x. Adjacent, remove the pump plunger from the plunger cover. Note the guide pivot on the plunger shaft; the plunger cam pushes against this to stroke the pump. Besides note the spring, which was rusted in a compressed state; this pump wasn't stroking at all.

11. Using a screwdriver, gently pry the oil seal from the pump cover (shown) and from the pump body. They're both a adequately gentle press fit and come out quite hands.

12. With the pump stripped, clean all the parts thoroughly. Following degreasing and rinsing, nosotros gave everything a 15-minute soak in an ultrasonic bath.

13. With the parts make clean it's time to start putting the pump dorsum together. Here we've just installed the new plunger cam seal (in green), using the quondam seal as a guide to help push the new seal into identify.

fourteen. Despite expectations, the ultrasonic bath didn't release the seized pump plunger spring and so we carefully worked each gyre apart.

15. Side by side, install the new seals in the pump embrace and the pump body. The seal for the pump body should be installed apartment or safe side out, the seal for the cover should be installed flat or prophylactic side in.

16. Side by side, install the pump plunger with its spring in the pump cover, with the threaded shaft to the exterior of the encompass and the cam guide pin positioned under the seal.

17. Making sure the shaft washers are properly located, install the plunger cam complete with the worm gear, pins and springs, followed by the large flat washer. Install the new embrace gasket and lightly grease the pump plunger shaft before installing the cover.

18. With the embrace secured with new Phillips screws, key the caster jump to the trunk. Follow with the pump pulley, turning it counterclockwise under bound pressure until the hole for the whorl pin lines up, and then install the pivot.

xix. Next, install the shims removed earlier, followed by the pump adjusting plate, moving ridge washer and securing nut.

20. With new body to engine gasket in identify, install the oil pump to engine using new mounting screws.

21. Reconnect oil hoses and the throttle cable. Check for pump stroke by turning the manual starter plate. Adjust cable preload and then the adjuster plate aligns with the arrow on the pulley, then drain the system per the manual. MC

Source: https://www.motorcycleclassics.com/classic-motorcycle-repair/yamaha-autolube-zmmz16jazhur/

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