Hydraulic-drive centrifugal pumps (Ace FMC-HYD, Hypro 9303/9306/9307, Banjo HY) are simple and reliable, but they only work right when the oil going to the motor matches what the motor was built for. Hot oil, a slow pump, or a pump that won’t turn are usually flow problems, not a failed motor.
1. Know your motor’s flow rating
On an Ace pump the motor code is in the model number (see Ace model numbers explained):
| Ace motor | Oil flow | Restrictor orifice |
|---|---|---|
| 204 | About 4 GPM | BAC-79-5 (.078) |
| 206 | About 7 GPM | BAC-79-7 (.109) |
| 210 | About 10 GPM | BAC-79-7 (.109) |
| 304 | About 9–11 GPM | BAC-79-8 (.125) |
| 306 | About 16.5 GPM | BAC-79-9 (call to order) |
| 307 / 310 | 16–25 GPM | Per the pump sheet |
Hypro’s HM1C, HM4C and HM5C motors each cover a different flow range; the pump’s page lists it.
2. Match it to the tractor’s hydraulics
- Set the flow on the tractor’s remote valve to the motor’s rating. Too much oil overspeeds the pump and heats the oil; too little and the pump never reaches pressure.
- Use the restrictor orifice that goes with your motor. It limits the oil the motor can take so it doesn’t overspeed.
- Closed-center and load-sensing tractors need the right restrictor or flow control for that system. Ace makes PWM motors (206-PWM, 304-PWM) with an integrated control valve for closed-center systems. If you’re not sure how your tractor is set up, call us before you run it.
- Case drain (CD) motors need the third line run back to the reservoir with no restriction.
3. Won’t turn at all
Check that the pressure and return hoses aren’t swapped. Ace motors have a reverse check valve that blocks backward flow, so a reversed hookup just sits there. Then check the pump end isn’t seized: rust or debris can lock the impeller in the housing, especially after storage.
4. Oil leaking at the motor
Oil at the motor shaft, or between the motor and the pump, is the motor’s seals. Rebuild it with the motor kit:
| Motor | Kit |
|---|---|
| Ace 200-series (202, 203, 204, 206, 210) | RK-BAC-75-HYD-L |
| Ace 300-series (304, 306, 307) | RK-BAC-75-HYD-300-L |
| Ace M-series (M16, M22, M25) | RK-BAC-75-M |
| Hypro HM1C / HM4C / HM5C | 3430-0748 (motor bearing and shaft seal) |
Spray mix (not oil) dripping behind the pump is the pump’s mechanical seal instead; see pump leaking at the shaft.
Open your pump in the Pump Finder and pick “Hydraulic motor problems” to see the motor, restrictor, check valve, flow limiter and kit for that exact model, for example FMC-150F-HYD-206 or 9303C-HM4C.
Spray Center Electronics stocks pump parts and repair kits for Ace, Banjo, Hypro/SHURflo and Annovi Reverberi (AR) pumps in Spokane, WA. Part numbers here come from the manufacturers’ parts sheets; when your pump has been modified or the tag is gone, send a photo to sales@spraycenter.com or call (509) 838-2209 and we’ll match it before you order.