After 8 years of doing wet stacking on generators, I finally saw what clean exhaust looks like

I run a shop near Tulsa that services backup gensets for a few hospitals. Last month I took a load bank test on a 500 kW Cummins that had been running at 30% load for years. The exhaust pipe had tar dripping out. After a proper 4 hour full load run the soot just vanished and the pipe turned gray. Has anyone else had luck fixing wet stacking on older units or do you usually swap the injectors first?

2 comments

2 Comments

loganburns18d ago

Dang, that's wild! I've seen plenty of gensets that look like they're sweating tar, but a full 4 hour bake-off fixing it that clean is impressive. Most guys I know just swap injectors and call it a day, but sounds like the real fix was just giving it a proper workout. Those hospital backup units are the worst offenders since they barely ever get pushed hard enough. Probably worth doing a load bank test like that once a year just to burn all that built up crap out of the system.

jenny58018d ago

My buddy runs a fleet of rentals and he had a unit that was just constantly wet stacking, no matter what he did. He finally took it out to a job site where they were running a bunch of heavy pumps nonstop for like six hours and the thing cleared right up on its own. Came back looking like a brand new engine inside, no more black goo or smoke. It's crazy how much those things just need to actually work hard instead of just idling.