They didn't learn their lesson from the plenums?
It's poor planning, design, and execution. Sorry but if something made of steel and cast iron is designed to be used exclusively outdoors, it needs to be taken into account that those metals rust fast, and quality primer, paint, and sealants need to be used. I foresee these engines crapping out mighty fast.
Generac, Guardian, Honeywell, Siemens, Centurion, Watchdog, Bryant, Olympian & Carrier Liquid Cooled Home Standby & Commercial generator troubleshooting and repair questions
I did the start up on a brand new 24kw a few weeks back that hadn't been left outside, stored in a warm dry warehouse and looked more rusty than some of the units that have been outside for a decade. The manifold, flexible exhaust connector, and one of the cylinder head pieces will be replaced for aesthetic reasons.