I have a 1990 Komatsu PC220-LC 5 excavator. I have had two 24 volt 35 amp alternators go bad in the last year. The technician said that they were being damaged by the hot wire being grounded or arced. We found the oil level sensor was causing a ground leading back to alternator. Has anyone else had a similar problem?
On Dash 6 machines the output post of the alternator goes through a large cable to the battery post of the start solenoid on the starter. It is big and heavy duty to withstand all kinds of amps, but if it grounded out it could cause alternator failure as there is no safety breaker. An oil pressure sensor is a tiny wire that would just explode if totally grounded out, and do nothing to the large output alternator. That would be my analysis, your alternators may of faced other problems like maybe bad batteries, incorrect boosting or just was not that good to begin with. Simon C
I agree with Simon on this one and think you need a new technician and a source of better quality replacement alternators. You would have burnt wires if there any shorts or arcing. An alternator is not damaged easily if the output is shorted to ground and would take about 30minutes at full current with a short to cause overheating in the alternator. The main cable would be burnt and blow open circuit from the inrush of current from the battery's also flowing to ground. What typically overheats the windings is the alternator charging hard with low engine rpms. This causes reduced air flow through the windings and over heating and is obvious to your technician when inspected. If the main diodes fail you would have burnt windings and failed diodes when inspected. If you do a lot of idling the alternator can get seriously hot. Is the pulley on the alternator the correct size?
Good explanation of what happens with high load and low air flow 007. Also if pulley is slipping there is less flow of air but the heat of charging is still there. And yes for the big cable to arc would leave some good evidence. Simon C