CM871 things to check after purchase?

[Rawze]

(03-29-2016 )Hedley Wrote:  the Vin numbers on the string of 2009 Prostar we bought calls for a 14V 325 amp alternator, we had issues like Cluster gauges going dead, blend door would open or close and power to the A/C compressor clutch would go out, the drivers would have to pull over and turn off the ignition for about 15 seconds and the A/C would power back up for a few hours and then go dead again and no..it was not the circuit breakers resetting, all these issues went away once we installed the correct alternator that the Vins called for....9 out of the 28 trucks had 12V 180 amp alternators and those were the ones giving us fits, take it with a grain of salt...if you have electrical issues with yours then give your Vin to any Navistar dealer and ask what your Vin calls for or just dismiss this as Hedley's terrible brain going south again.


*** the replacement alternator is PN# BLP4002H, it is a 12V 325amp Leece Neville

I look back at this and now know that many alternators have gotten really cheap in their design and create a lot of electrical noise. I think even cummins is now saying the CM2250 and Cm2350 are susceptible to alternator noise and creating injector and engine run/efficiency issues. I have heard they are recommending a filter right at the alternator as close to the source of noise as possible. this makes sense.

I have always had a very large capacitor on my electrical system at the inverter to prevent noise. Maybe that is why I have never had an issue. I recently replaced that inverter and removed the capacitor and noticed quite a lot more noise in the electrical system. I have re-installed that capacitor right at my alternator (at the source of the noise) to see if it helps reduce Alternator noise even further this time. I painted it black with a rubberized coating to protect it from the elements.

   

*** update(2018): This was the best decision I have made for my electrical system as a whole.. WOW, putting that capacitor at the alternator makes the electrical system quiet as a mouse. Makes a huge difference when placed here right at the source of the noise.