Replacement Onan 7500 Diesel Generator for a Class A Motorhome

Updated 10/21/2026 | Published 10/20/2026

Products Featured in This Question

Cummins Onan QD 7500 Diesel Generator - 7.5 kW - 120V

$12711.39

Cummins Onan EC-AGS+ Auto Generator Start System - Bluetooth - Diesel RVs

(1)

$453.92

Question:

The older 7,500-watt Onan diesel generator in our Class A motorhome needs major repairs, and we're considering replacing it instead. We have 50-amp service and two rooftop air conditioners. Do you carry a comparable replacement, and what should we check before ordering? We'd like to reuse our existing wiring, inside start switch, and exhaust if possible.

asked by: Jack

Expert Reply:

Hey Jack! I recommend the Cummins Onan QD 7500 Diesel Generator # CM529ZR as a comparable replacement for your older 7,500W Onan. It provides 7,500 watts of 120V power and features a sound insulated housing for quieter operation.

The generator measures 36.4" long x 24.2" wide x 22.3" tall. You'll want to compare those dimensions with your existing generator and verify the mounting, wiring, fuel, and exhaust connections. Your existing wiring, inside start switch, and exhaust may be reusable depending on your current setup.

If you'd like to add automatic generator starting, the Cummins Onan EC-AGS+ # CM58GR is a compatible option. It allows you to start and stop the generator from your phone using Bluetooth and can automatically start based on temperature or low battery voltage.

What model number is on your current Onan generator?

expert reply by: Robin H

CM529ZR
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CM58GR
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Jack

10/21/2026

I checked the label and my current generator is an Onan 7.5HDKAJ. Is the one you recommended a good replacement for that model?

Robin H.

10/21/2026

@Jack yes, the Cummins Onan QD 7500 # CM529ZR is a great replacement option for your older 7.5HDKAJ. It provides the same 7,500-watt, 120V output with modern inverter technology. You'll just need to verify the mounting dimensions and connections since it isn't a direct bolt-in replacement.