Forum Discussion

devildog1971's avatar
devildog1971
Explorer
Aug 17, 2018

7500 cummins onan

how often should the oil be changed in the onan 7500 watt diesel if only holds 3 quarts of oil, and ours gets used a lot in the summer. one other question I did not do enough research when I bought our class A and bought one that does not have a slide out generator, Can you get to the spark arrestor and air filter without dropping the generator on the ground, those of you experienced with these generators please let me know what items can be serviced without dropping the generator, and what service requires dropping the generator thanks in advance for your help and advice. One other thing how hard is it to drop the generator to the ground to service it
Class A
  • Big_Katuna's avatar
    Big_Katuna
    Explorer II
    Aug 17, 2018
    The fuel filter and oil filter are concealed by a small panel that swings open by pinching a latch. Buy a set of line wrenches for the fuel filter. Also use a six point wrench on the drain plug.
    I have a label maker and print out the hours due next to the hour meter.

    There is a belt inside which requires dropping the genset. Supposed to be replaced at five years I think.
    Mine is thirteen, so crossing my fingers. It’s like $1300 to have the belt done.
  • FormerBoater's avatar
    FormerBoater
    Explorer
    Aug 17, 2018
    Well you are in luck!

    The QD7500 service schedule calls for oil and oil filter change every 150 hours

    Air filter service is longer, but it is inexpensive and you access both the oil drain plug, oil filter and air filter from underneath the generator---no need to drop the unit. You may as well change both while you are down there.

    As far as the spark arrestor goes, there are videos on the net that will demonstrate the method required to clean it. You will not need to drop the generator to perform this maintenance.

    Fuel filter change is also a recommended PM. Also accessible from below and no need to drop the generator.

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