Hi, I have another thread going, but I figured I'd try something more general. I'm an amateur mechanic when I need to be. I have a backhoe with a turbocharged Perkins 1004 (40T, AK series, 4.4l), and it's not developing full power. I'd say maybe 60-75%. Obviously, this would be because the engine isn't getting full fuel and/or air. This post is to look into the air issue. The engine had critter nest at the air intake, a critter which got in through a missing small (~1.5") plug in the air filter canister cover. I cleaned the nest out and put in new filters, which were also quite clogged. However, there weren't any holes chewed in the filters, so it appears the critter didn't make it downstream to the turbo. I also took the turbo out and it seems fine. One can hear it spool up. No visible smoke at any speed/load. However, in various testing I discovered that when I rev the engine at no load, I get positive back-pressure at the air filter (through the aforementioned plug). I would think that it should be substantially pulling air in, no? The question: Is this normal? If not: If there's some sort of blockage in the intake manifold, that would explain it. Also, some sort of issue with bad intake valves would do it, though the engine seems to have pretty low hours on it and runs fine up to the point where the power plateaus. Suggestions? Thanks kindly in advance.
I'm guessing that little plug is the dust evacuater. A touch of positive pressure by design. Air pressure differential and all that. It helps keep your filter a touch cleaner. Now if its pulsing or surging, that's a different matter
U should find out what the engine is rated for>> what are the no-load RPM's & is the engine getting there.?
Good call. Looking a little deeper (a lot really...) in a Perkin's manual, indeed, they seem to have this feature. Not much is said about it but I'll concur that's what's going on. Thanks!