Troubleshooting
2Symptoms & remedies
| Symptom | Cause | Remedy |
|---|---|---|
| Unsatisfactory or erratic operation of the generator | Improper governor operation causing over, under, and fluctuating engine speeds | Checking the entire electrical system with a continuity tester or ohmmeter may be required. The tests that follow can be performed without disassembly of the generator. |
| Loss of welding power | 1. Remove control box cover screws and lift off cover. 2. Visually check the rotary switch wiper blade and contact points for burned areas. If questionable contacts are observed, attach one lead of ohmmeter to left hand welding terminal stud; turn switch handle to contact to be tested. Touch the other ohmmeter lead to the reactor lead where it is clamped to the switch terminal. A low (less than 2 ohms) resistance reading should be obtained on the meter if there is a good contact in the switching members. 3. If switch checks out satisfactorily, examine all leads, terminals, and screw connections visually for opens or shorts. A point-to-point check with the ohmmeter will indicate any open circuit. 4. If connections appear all good, isolate the diode (see Control Box Section) attached to the small Circuit board back of the control panel top. Check the diode with the ohmmeter by alternately reversing the leads. If the diode passes current in one direction and not the other, the diode is probably good. 5. NOTE: A bad diode will cause the ignition to short and stop the engine. A marginal diode may operate sufficiently well to enable the engine to run but will not deliver enough current to excite the generator (flash the field). If there is any doubt as to the condition of the diode, replace it without question. Make sure, when replacing, that the arrow on the new diode points in the same direction as the one removed. 6. Isolate the small resistor from the diode and test with the ohmmeter. Resistance should measure 2.7 ohms + 5%. 7. Remove the end bell cover and cooling fan. Check the brushes in accordance with the procedure in the Maintenance Section. Check all connections for shorts or opens with the ohmmeter. 8. Isolate the two diodes from the end bell frame by removing the attaching nuts. Test as in Step 3. 9. Replace if marginal. 10. If loss of welding power is noticed only in the upper ampere ranges, it is very possible that the electrolytic capacitors are at fault. An ohmmeter will tell you if the capacitor is shorted but will not tell you if the capacitor is open or has changed value. Unless a special capacitor tester is available, substitution of capacitors known to be good is the quickest way of determining the condition of the suspect capacitors. Observe polarity closely when replacement is made. |
Fault codes and symptom→remedy steps extracted from this unit’s service/owner documentation; verify against the official manual before servicing.
Parts
120| Part # | Description | Qty | System | |
|---|---|---|---|---|
| 101K397 | *Gasket Kit, Bearing Plate | 1 | Gasket | Amazon eBay |
| 101K419 | Gasket Kit, Bearing Plate | 1 | Gasket | Amazon eBay |
| 101K427-02 | .002 “” Undersize | 2 | Bearing | Amazon eBay |
| 101K427-10 | .010 “” Undersize | 2 | Bearing | Amazon eBay |
| 101K427-20 | .020 “” Undersize | 2 | Bearing | Amazon eBay |
| 101K427-30 | .030 “’ Undersize | 2 | Bearing | Amazon eBay |
| 102A455 | Screw, Cap - Oil Base to Block | 1 | Gasket | Amazon eBay |
| 102B107 | Gasket, Oil Base Mounting | 1 | Gasket | Amazon eBay |
| 102D107 | Gasket, Oil Base Mounting | 1 | Gasket | Amazon eBay |
| 103B107 | Gasket, Gear Cover | 1 | Gasket | Amazon eBay |
| 10A1796 | Spacer, Cylinder Head to Cover | 1 | Spacer | Amazon eBay |
| 110A173 | Gasket, Cylinder Head | 1 | Gasket | Amazon eBay |
| 110A1733 | Head, Cylinder | 1 | Head | Amazon eBay |
| 110A1762 | Intake | 1 | Intake | Amazon eBay |
| 110A1763 | Exhaust | 1 | Exhaust | Amazon eBay |
| 110A1791 | Gasket, Valve Compartment | 2 | Gasket | Amazon eBay |
| 110A639 | Lock, Valve | 4 | Lock | Amazon eBay |
| 110A791 | Gasket, (1) Valve Cover, (1) Baffle | 2 | Gasket | Amazon eBay |
| 110A9042 | Rotocap, Valve TAPPET, VALVE | 2 | Air filter | Amazon eBay |
| 110B1731 | Gasket, Cylinder Head | 1 | Gasket | Amazon eBay |
| 123A191 | Gasket, Oil Fill Cap | 1 | Gasket | Amazon eBay |
| 13402047 | Cover, Cylinder Air Housing | 1 | Cover | Amazon eBay |
| 134A2048 | Screen, Air Inlet | 1 | Screen | Amazon eBay |
| 134B2046 | Plate, Cylinder Air Housing | 1 | Plate | Amazon eBay |
| 134C2045 | Link, Throttle | 1 | Link | Amazon eBay |
| 140A1063 | Adapter, Air Cleaner | 1 | Air filter | Amazon eBay |
| 140A1069 | Gasket, Adapter to Carburetor | 1 | Gasket | Amazon eBay |
| 140A921 | Gasket, Adapter To Carburetor | 1 | Gasket | Amazon eBay |
| 140C1053 | Cover, Air Cleaner | 1 | Air filter | Amazon eBay |
| 140P1055 | Element, Air Cleaner | 1 | Air filter | Amazon eBay |
| 141-661 | Seal, Rubber | 1 | Seal | Amazon eBay |
| 141-712 | Jet Assembly, Main (Adjustable) | 1 | Jet | Amazon eBay |
| 141A77 | (@de)Washer, Valve Seat Fibre. | 1 | Gasket | Amazon eBay |
| 141K748 | Kit, Carburetor Gasket | 1 | Gasket | Amazon eBay |
| 141P203 | Retainer, Felt Seal | 1 | Seal | Amazon eBay |
| 141P697 | Seal, Felt | 1 | Seal | Amazon eBay |
| 141P701 | Gasket, Bowl to Body | 1 | Gasket | Amazon eBay |
| 141P705 | Retainer, Seal | 1 | Retainer | Amazon eBay |
| 141P708 | Bowl, Fuel | 1 | Fuel filter | Amazon eBay |
| 149-149 | Filter, Fuel | 1 | Fuel filter | Amazon eBay |
| 149-150 | Bowl, Fuel Filter | 1 | Fuel filter | Amazon eBay |
| 149-202 | Screen, Fuel Filter | 1 | Fuel filter | Amazon eBay |
| 149A3 | Gasket, Fuel Pump Mtg. 45 502-3 ! Connector, Fue! Filter | 1 | Gasket | Amazon eBay |
| 149A858 | Gasket, Diaphragm | 1 | Gasket | Amazon eBay |
| 149A95 | Gasket, Valve | 2 | Gasket | Amazon eBay |
| 149B79 | Filter, Fuel | 1 | Fuel filter | Amazon eBay |
| 149D1213 | Pump, Fuel | 1 | Pump | Amazon eBay |
| 149K526 | Kit, Fuel Pump Repair | 1 | Fuel pump | Amazon eBay |
| 15-20 | Spark Plug | 20 | Spark plug | Amazon eBay FridayParts $130.18 |
| 150B1043 | *Shaft & Arm, Governor | 1 | Oil filter | Amazon eBay |
| 150B1270 | Stud, Speed Adjusting | 1 | Stud | Amazon eBay |
| 154A733 | Gasket, Carburetor Mounting | 2 | Gasket | Amazon eBay |
| 159C948 | Tank, Fuel Mounted | 1 | Fluid | Amazon eBay |
| 160A43 | Gasket, Breaker Box Mounting | 1 | Gasket | Amazon eBay |
| 160A550 | Gasket, Breaker Box Cover | 1 | Gasket | Amazon eBay |
| 167-28 | Plug, Spark | 1 | Spark plug | Amazon eBay |
| 167-4 | Swivel, Governor Control Arm Bracket | 1 | Swivel | Amazon eBay |
| 167A1524 | Cable, Spark Plug Key 2 | 1 | Hose | Amazon eBay |
| 167A1547 | Cable, Spark Plug Key 1 | 1 | Hose | Amazon eBay |
| 167A188 | Bracket, Throttle and Choke | 1 | Bracket | Amazon eBay |
| 1710A367 | *Bearing, Camshaft (Precision) | 1 | Bearing | Amazon eBay |
| 191-794 | Housing Assembly | 1 | Housing | Amazon eBay |
| 191-795 | Cap Assembly, End | 1 | Cap | Amazon eBay |
| 191-796 | Armature Assembly | 1 | Armature | Amazon eBay |
| 191-797 | Cap Assembly, Drive End | 1 | Cap | Amazon eBay |
| 191-798 | Drive Assembly, Complete | 1 | Drive | Amazon eBay |
| 191-799 | Bolt Assembly - Through | 2 | Bolt | Amazon eBay |
| 191-800 | Brush, Positive | 2 | Brush | Amazon eBay |
| 191-801 | Brush, Negative | 2 | Brush | Amazon eBay |
| 1910769 | Bushing, Governor Control Bracket | 2 | Bushing | Amazon eBay |
| 191C768 | Guard, Air Inlet | 2 | Guard | Amazon eBay |
| 191C780 | Motor, Starting | 1 | Motor | Amazon eBay |
| 192A308 | Sheave, Starter Rope | 1 | Starter | Amazon eBay |
| 19S16A72 | *Pin, Main Bearing Stop | 1 | Pin | Amazon eBay |
| 1S5A6-05 | .005 “’ Oversize | 2 | Oil filter | Amazon eBay |
| 1SA62 | Standard | 2 | Oil filter | Amazon eBay |
| 20123A486 | Valve, Breather | 1 | Valve | Amazon eBay |
| 21509BI718 | Washer, Valve Compartment Cover (Copper) | 1 | Washer | Amazon eBay |
| 2210A1751-02 | Intake | 1 | Intake | Amazon eBay |
| 2310A1751-05 | Exhaust (Stellite) | 1 | Exhaust | Amazon eBay |
| 2410A1783 | INSERT, EXHAUST VALVE SEAT (STELLITE) | 1 | Insert | Amazon eBay |
| 268526AI74 | *Plate, Rear Bearing (Excludes Bearing) | 1 | Plate | Amazon eBay |
| 305C480 | Bracket | 1 | Bracket | Amazon eBay |
| 402A290 | Bushing, Mounting Cushions | 4 | Bushing | Amazon eBay |
| 449A45 | Spacer, Fuel Pump Mounting | 1 | Pump | Amazon eBay |
| 501A7 | Line, Flex-fuel Filter to Pump | 2 | Hose | Amazon eBay |
| 502-2 | Elbow, Fuel Filter Outlet | 1 | Fuel filter | Amazon eBay |
| 502-20 | Elbow, Fuel Pump Inlet | 1 | Fuel pump | Amazon eBay |
| 502-313 | Elbow (1) Carburetor inlet (1) Fuel Pump Outlet | 1 | Fuel pump | Amazon eBay |
| 502-46 | Nipple, Fuel Filter to Tank | 1 | Fuel filter | Amazon eBay KuduParts $23.00 |
| 503A516 | Hose, Breather | 1 | Hose | Amazon eBay |
| 503A588 | Line, Fuel Pump to Carburetor | 1 | Hose | Amazon eBay |
| 503B589 | Elbow, Oil Balance Line | 1 | Oil balance elbow | Amazon eBay |
| 509-65 | Seal, Primer Lever "O" Ring | 2 | Seal | Amazon eBay |
| 509A40 | *Seal, Gear Cover | 1 | Seal | Amazon eBay |
| 509A41 | Seal, Bearing Plate | 1 | Seal | Amazon eBay |
| 509OP5 | Seal, Oil - Governor Shaft | 1 | Seal | Amazon eBay |
| 509P8 | *Seal, Oil - Governor Shaft | 1 | Oil filter | Amazon eBay |
| 516-1 | Pin, Gear Cover (5/16 x 3/4’) | 1 | Oil filter | Amazon eBay |
| 516-130 | *Pin, Governor Cup Stop (In Gear Cover) | 1 | Oil filter | Amazon eBay |
| 516-59 | Pin, Cotter | 1 | Pin | Amazon eBay |
| 518-129 | *Gasket, Fuel Pump Mounting | 1 | Gasket | Amazon eBay |
| 526-115 | Washer, Flat (5/16) | 1 | Washer | Amazon eBay |
| 526-6 | Washer, Flat (#12) | 1 | Washer | Amazon eBay |
| 526-63 | Washer (Copper) Fuel Pump Mounting | 2 | Pump | Amazon eBay |
| 540A1048 | Base, Air Cleaner | 1 | Air filter | Amazon eBay |
| 800-50 | Screw (3/8-16 x 1 “’) | 2 | Screw | Amazon eBay KuduParts $85.00 |
| 800P32 | Cap - GEAR COVER (5/16-18 x 2-1/4) | 1 | Oil filter | Amazon eBay |
| 812-155 | Screw (1/4-20 x 1-1/2%) - Stator Mounting | 1 | Screw | Amazon eBay |
| 813-108 | Screw (10-32 x 1-1/2%) - Stator Mounting | 1 | Screw | Amazon eBay |
| 815-104 | Screw (8-32 x 5/16 *) | 1 | Screw | Amazon eBay |
| 815-147 | Screw, Phillips Flat Head (#6-32 x 5/8") | 2 | Bolt | Amazon eBay |
| 815-46 | *Screw, Governor Yoke Mounting (Special) | 2 | Oil filter | Amazon eBay |
| 850-30 | Washer, Lock (#10) | 1 | Washer | Amazon eBay |
| 850-50 | Nut, Hex (10-32) | 1 | Hex nut | Amazon eBay |
| 850BI23 | Seal, Bearing Plate | 1 | Seal | Amazon eBay |
| 853-16 | Washer, Lock (3/8) | 1 | Washer | Amazon eBay |
| 865P22 | Nut, Wing - Air Cleaner | 1 | Air filter | Amazon eBay |
| I23AI19 | Tube, Oil Fill | 1 | Oil fill tube | Amazon eBay |
| I23BItIS | Line, Oil Balance | 1 | Oil balance line | Amazon eBay |
Service & wear parts shared with every machine that uses this engine. Confirm the exact part for your serial number.
Common questions
What engine is in the Cummins/Onan 5.0N8-343E?
The Cummins/Onan 5.0N8-343E welder is powered by the Cummins/Onan NB engine.
About
Cummins/Onan 5.0N8-343E — welder. Specifications and parts compiled from manufacturer documents.