Cat 615 scraper puzzle

Hey everyone. I've got a situation I'm trying to work through. The machine rolled backwards off a slope and ended up upside down. Took about 6 hours to flip it back over. After letting it sit for a few weeks, I repaired some crushed lines on the neck. Started up fine and idles okay, so I drove it 4 miles to where it is now. But here's the issue—the engine sounds like it's working really hard the whole time.

I've already gone through quite a bit of troubleshooting. New filters all around, pulled and cleaned the aftercooler, had the injection pump rebuilt, and checked the hydraulic control valve relief valves. Then I found the oil pressure was running at 115 psi, which seemed high. I swapped out the oil pump relief valve and got that sorted, but the engine is still straining badly.

Does anyone have other areas I should be looking at? Any ideas would really help. Thanks for reading through all this.

Did the engine keep running for more than just a few seconds right after it flipped over?

A quarter teaspoon of oil sitting on top of the pistons is enough to bend the connecting rods. You should have pulled the injectors and cranked the engine to clear out any residual oil before you started it. After everything you've already done, you'll probably end up asking how to find a missing alternator because a piston left the block.

It shut off right away.

I checked all that already at the start, which is why I'm stumped. It has to be something else on the machine.

Nobody actually shut the engine off? That's not a good sign. A diesel will typically keep running upside down for a few seconds without outside help, even though it'd have no oil pressure. I'm thinking the problem is in the engine itself. My suggestion would be to drop the oil pan and inspect the condition of the main and rod bearings.

Though I'm not totally certain about this, I think I might be wrong on that. What stands out to me is that the engine stopped on its own instead of somebody turning it off.

What engine model does it have?

I'd guess 3306.

I'm not sure whether the operator shut it down or not, but it could have happened. What matters to me is that it starts normally and sounds good – I even drove it 4 miles. If there were bent connecting rods or push rods, something would have broken by now, which would be fine. Anything bent would show up in a compression test anyway. I changed the relief valve on the oil pump and the oil pressure went back to normal. The original one was clearly stuck shut. I really appreciate you guys helping out on this.

We've had a few small dozers with bad EGR coolers that bent rods, and you could definitely hear something was wrong plus see white smoke. I'd be looking at the engine mounts—broken bolts, bent metal, that kind of thing. Another question: how's the steering working? Follow-up linkage could be messed up too. That was a pretty hard hit, so honestly almost anything's possible at this point.

Re

Started with it only turning left, so I rebuilt the steering valve and got that sorted—steers fine now. The engine purrs like a kitten and starts on first crank, but it feels like it's not getting enough air. There's light black smoke and no boost coming through. The hydraulic tank gets really hot fast now. Could the hydraulics be pulling the RPMs down below what's needed for the turbo to kick in?

Go back and double-check the valve you just fixed. A valve that's only partly open can build up heat in the hydraulic oil and make the engine work hard. You'll need to pressure test to find out which valve it is and where—guessing won't cut it.

I'd start by checking the pump pressure when you've got the hydraulic controls in hold position—look for high pressure there.

I'd look at the paddle wheel and its control setup, plus check the 2-speed function. Those lines going to the paddle motor could be crushed from the rollover, and if that control stays engaged, that could be what's straining the engine.