Catch can fills up fast after just 2 days driving… is this a problem?

Hey everyone,

I drive a 2017 Ford Explorer Sport. Recently, I had some major work done—replaced the water pump, cam phasers, guides, and timing chain—due to the infamous timing chain rattle during cold starts. Ever since then, my UPR 8oz catch can has been filling up way too quickly. I’ve been having to empty it every two days with just city driving. Before this work, I only had to empty it during routine service intervals.

The dealership checked the engine, ran for error codes, replaced the PCV valve, and updated the PCM but said everything was fine. Their advice? Take off the catch can entirely. I’m torn between trusting them or taking the car to another dealer for a second opinion.

The car drives fine, but the rapid blow-by buildup is driving me nuts. It’s not just water vapor—it seems excessive. Could there be something else going on? Any ideas?

How many miles are on it? Too much blow-by could mean a few things, like a worn turbo impeller or compressor shaft. But if you’ve done regular maintenance, I’d definitely suggest getting a second opinion, especially since they’re telling you to just remove the catch can.

@Reagan
Thanks for replying! It’s got just under 80,000 miles on it—not super high. I’ve stuck to my maintenance schedule. I’m actually taking it to another dealer this Saturday. A little annoying since they won’t have my service history, so I’ll have to explain everything again, but it feels like the right move.

@Rene
Yeah, once the 3.5 EcoBoost engines get some miles on them, you start seeing more blow-by—it’s pretty common, even for the 2.3 EcoBoost. Turbocharged engines at these outputs seem to just have this issue. Even luxury brands like Mercedes deal with it. Turbos naturally leak some oil just from doing their job.

@Reagan
I get that, and I’d be fine if this was gradual. But here’s the thing: before the recent engine work, I emptied the catch can maybe once a year, and it barely had an ounce in it. Now, I’m emptying it every couple of days. Something changed drastically after they did the timing chain and phasers. It doesn’t feel normal.

@Rene
That’s wild. Maybe the new timing components tightened everything up, which increased boost or pressure, causing more blow-by? Just brainstorming, but definitely worth looking into further.

That much blow-by isn’t normal at all.

Skyler said:
That much blow-by isn’t normal at all.

Right? I was shocked when they suggested going back to stock because “that’s how the engine was designed.” If anything, removing the catch can feels like it’d just hide the problem and cause bigger issues later.

@Rene
Dealerships can be clueless sometimes.

Forgive me if this sounds dumb, but what even is a catch can?

Kai said:
Forgive me if this sounds dumb, but what even is a catch can?

Not dumb at all! A catch can collects oil vapor and contaminants from blow-by before they get into the intake system. If you search online, there are tons of great visuals and guides that explain it better than I can!

Kai said:
Forgive me if this sounds dumb, but what even is a catch can?

I was wondering the same thing. Learned something new today!

No way that’s normal. What’s in the catch can? Just oil? Have you checked your oil level—maybe it’s overfilled?

Tatum said:
No way that’s normal. What’s in the catch can? Just oil? Have you checked your oil level—maybe it’s overfilled?

It’s a mix of oil and other gunk. The oil level’s fine, though, so overfilling isn’t the issue. It’s just weird how quickly it’s filling up now.