Perhaps you've heard oil catch cans, but you don't know what they actually do. Have no fear because catch cans are the topic in this episode of Engineering Explained.
Not only does host Jason Fenske explain what an oil catch can is, but he looks into if they're actually worth the extra money, especially for those with modified vehicles.
First, a summary of what catch cans do. In engines with direct injection, blowby of high pressure past the pistons can happen during regular combustion. This pressurizes the crankcase.
Thankfully, smart automakers crafted the positive crankcase ventilation system, which sends the pressure back into the intake manifold. Good stuff, except, it can take oil and other deposits from the blowby with it. Thus, oil and other contaminants can coat the intake valves and that could lead to problems down the road. What a catch can aims to do is route the pressure to the intake manifold and send the oil or other junk within it to the bottom of the catch can.
Next, Jason looks at if oil catch cans really do work. The answer is yes. While a catch can won't stop every last particle of contaminant from entering the intake manifold and coating the valves in a direct-injection engine, the less unwanted buildup the better. Jason cites a study from the Society of Automotive Engineers that showed buildup on intake valves significantly decreased when contaminants were routed away from the intake manifold. So, yes, a catch can isn't a bad idea. At a minimum, it's not a scam.
Finally, Jason looks at the value factor of various catch cans. Some companies sell catch cans for over $200, while others are as cheap as $25. The only major difference Jason found was the the lack of a bronze filter in the cheapest option, which will do a better job of sorting out the contaminates. Aside from the filter, size also increased the price significantly. For those who don't want to empty out a tiny catch can frequently, the larger units are helpful.
Check out the full explanation in the video above.
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