JD 350G Oil dripping out vent tube... again new engine

We had a new 6090 engine put into our 2012 JD350G (serial # 1FF350GXTCE808707) last summer because oil was running out of the vent tube. The JD field rep said we needed a replacement engine. Cost us 20K with us handling the install ourselves. The engine came with the wrong head, so JD swapped it out at no cost to us. Now here we are, less than a year later, and oil is dripping out of the vent tube again. We've got less than 100 hours on this engine. The old one was pumping oil out pretty heavily, but this time it's just dripping—though it's enough to fill up a pan underneath. Oil level is sitting just over the fill mark. We're planning to change the oil again. Is there anything like a PCV system that could be pressurizing the crankcase enough to cause this? Any ideas would be really helpful. Thanks in advance. Mike

That's right. If it's not spinning fast enough, stops altogether, or gets clogged somewhere, you could get that behavior. I doubt that engine has a crankcase pressure sensor, so you probably wouldn't be seeing any pressure codes.

I'm not sure what spins inside it exactly. I took mine apart before we replaced the old engine and cleaned it out. The JD rep figured the old motor had blowby causing all that oil to pour out the vent hose - we could've probably filled a bucket in twenty minutes with how much was coming out. He never really confirmed it though. If this new one isn't working right either, what would it take to fix it? Would we need a whole new vent, or would a repair kit do the job? Any thoughts on what the issue could be?

Those two words jump out at me—"rep" and "probably"—because they led to a $20K bill that might not have been necessary in the first place.

There's a rotating conical disc stack inside the thing. When we test them, we measure the rpm. It should be spinning at 6000 rpm or higher when you're at fast idle with the engine at full operating temperature. We use a multimeter set to frequency or Hz mode, wired to a crank position sensor placed on top. So you'd need to run a test to figure out if that's actually what's going on here.

We ordered a new vent tube since we reused the old one when we installed the new motor. The field rep didn't have any other ideas about what caused the problem with the original engine. He said it was blowby and checked the turbos and some other things, but found nothing else that would cause it. We went with what he said. That's water under the bridge now. Maybe he was right.

Did you end up changing the PCV? Did that take care of it? I've got the same excavator with the same issue and I'm trying to figure out where to start.

Did you figure out what was causing it? We've got one doing the same thing.