For further information, please contact the RIVA After Sales & Service Department.
| Problem | Cause | Corrective action |
| 1. Transmission oil temperature too high | Insufficient water flows through oil heat exchanger | Increase water flow |
| Drain sludge from oil cooler | Clean oil cooler | |
| Undefined range, clutch slipping | Adjust mechanism | |
| 2. Transmission oil temperature too low | Excessive water flow through heater exchanger | Reduce water flow |
| 3. Oil pressure upstream of oil cooler and filter too high (*) | Clogged oil filter | Clean filter and drain off oil sludge |
| Oil cooler dirty | Clean oil side of oil cooler | |
| 4. No operating oil pressure (*) | No oil in transmission | Add oil |
| Wrong rotation direction at transmission input | Use special transmission version | |
| Faulty display unit | Remedy fault | |
| 5. Operating oil pressure too low (*) | Oil viscosity too low | Use a prescribed oil grade |
| Incorrect oil pump ratio | Adjust oil pump ratio to suit engine operating speed range | |
| Defective oil pump | Replace oil pump | |
| Pressure relief valve leaking | Remedy the fault | |
| Timeswitch for pressure modulation defective | See Manufacturer’s documents | |
| 6. Operating oil pressure too high (*) | Oil viscosity too high | Use a prescribed oil grade |
| Incorrect oil pump ratio | Adjust oil pump ratio to suit engine operating speed range | |
7. Drive interrupted between transmission input and transmission output; clutch not transmitting torque |
Mechanical transmission actuation: incorrect shift angle | Adjust setting |
| Electrical transmission actuation: electrical system fault | Remedy electrical system fault | |
| Defective solenoid valve | Replace | |
| Longitudinal valve stuck | Remedy fault | |
| No operating oil pressure | See “No operating oil pressure” or “Oil pressure too low” | |
| 8. Drive between transmission input and transmission output cannot be interrupted; clutch does not disengage | For possible causes and remedial actions, see “clutch not transmitting torque” fault | Use a prescribed oil grade |
| Adjust oil pump ratio to suit engine operating speed range | ||
| 9. Clutch slips at high engine speed | Operating oil pressure too low (*) | See remedy for “Operating oil pressure too low”. If the fault cannot be remedied on board, proceed at reduced engine speed - so that the clutch does not slip - until repairs can be carried out. Avoid changes in direction or only change direction with the propeller almost at a standstill and with engine idle speed as low as possible |
| 10. Oil level decreases rapidly (as indicated on the dipstick). See maintenance job “Oil level check” | Leaks on housing joints or oil lines, oil escaping from shaft seals | Correct mechanical fault |
| Oil cooler leaking into cooling system | Remedy fault, replace oil cooler if necessary | |
| 11. Oil level increases. See maintenance job “Oil level check” | Water entering the oil circuit from the cooling system | Correct mechanical fault |
| 12. Transmission is too loud at certain speed ranges | Torsional vibration resonance of propulsion system in engine idle speed range | Avoid critical speed range. Use more suitable flexible coupling (see Manufacturer’s document) |
| 13. Transmission too loud at engine idle speed range | Torsional vibration resonance of propulsion system in engine idle speed range | Increase engine idle speed range |
| 14. Engine stalls following rapid change from “Ahead” to “Astern” | Engine idle speed too low | Increase engine idle speed range |
| Change in direction made too quickly or made at excessive craft speed | Change direction (see Manufacturer’s document) |
If the fault cannot be remedied, the transmission lubricating oil supply is also at risk. Proceed at reduced engine speed only until repairs can be carried out.
(*) see monitoring data.