Any idea why my excavator stalls when I use the boom or stick after fixing the swivel joint?

[James R.]

I've got a Caterpillar 315L excavator that sat for years before I got it. I went through it pretty hard, rebuilt cylinders, got it running decently, then had tracking issues. Ended up rebuilding the swivel joint, and that actually fixed the tracking problem. The machine now tracks strongly and feels normal there.

But now I've got a new issue. Whenever I move the boom or stick and deadhead it, the engine bogs hard and sometimes stalls completely. It runs fine at idle and light movements, but as soon as it's under load, it just can't handle it.

 

[IamBruce_Driver]

Does it blow black smoke when it bogs, or does it just fall on its face with little smoke?

1. Black smoke = fuel is there is likely a hydraulic overload
2. No smoke = fuel starvation/delivery issue

 

[USVeteran]

I had a similar issue on my Caterpillar 315L excavator after it sat for a long time. If your engine bogs or stalls under load, it's usually one of these:

1. Fuel system:
Clogged fuel filter or weak lift pump
Mine ran fine at idle, but bogged under load because of this.
2. Hydraulic overload:
The pump may be pushing too much pressure
The regulator could be off
3. Air/exhaust:
Dirty air filter or restricted exhaust

Start with fuel filters first, because that's the most common fix.