Radium 0.75 in ID Breather Filter, Green

Radium Engineering 0.75 Inch ID Breather Filter, Green - Part #18-0042

Every catch can, valve cover breather, and surge tank vent needs something on the open end, and the choice is usually between a cheap chrome cone that falls apart or nothing at all. Radium's 18-0042 is a proper small breather filter: a 0.75 inch inlet, a molded rubber base, a green cylindrical element, and dimensions small enough to tuck under a K-series valve cover or behind a catch can where a bigger filter won't fit.

What It Is and Why It Works

A breather filter lets crankcase pressure or tank vapor escape while keeping dirt out of the system on the way back in, which matters on a catch can that's vented to atmosphere and on a surge tank vent line that ends in the engine bay. This one is a straight-inlet cylinder filter with a rubber base that clamps onto a 3/4 inch tube or hose barb. The filter measures 2.17 inches across the base, 2.0 inches at the top, and 2.38 inches tall, so it clears most catch can lids and fits between a valve cover and a fuel rail. Radium uses this filter on its own catch cans and surge tank vent kits, and the green element matches the rest of their hardware if you care about that.

Specs

Fitment

Not vehicle-specific. Measure the outside diameter of the tube it's going on; the 0.75 inch figure is the filter's inlet ID, and a 10AN breather fitting or a 3/4 inch barb is the usual match.

What to Know Before You Buy

Clamp it. The rubber base grips a 3/4 inch tube well enough for a mock-up but not for a vibrating engine, and a breather filter rolling around the bay is how oil ends up on the exhaust. Keep it away from the header; the element and the rubber base are not made for radiant heat. On a catch can that's part of a PCV loop rather than vented to atmosphere, you don't need this at all, and on a surge tank vent, make sure the vent line terminates outside the cabin before you cap it with a filter. Clean it with mild soap and water when it looks dirty; it isn't oiled and doesn't need to be.