All 1997 and Newer LS1/LS2/LS3 etc, LT1 & LT4, 1989 Turbo Trans Am, 3800 Series II, Ecotec
This valve cover breather assembly replaces the original oil fill tube on the factory valve cover. The base is CNC-machined from billet aluminum for precise fit, and the included silicone O-ring is specially designed to prevent oil seepage at the base of the breather. The filter base is microfinished for surface protection and good looks, and is easily hand-polished to a mirror-like appearance. The removable filter element is a high-quality reusable unit from S & B Filters, which is securely retained in the filter base by a specially-machined retention groove in the top of the base.
The purpose of this valve cover breather is to vent unwanted accumulation of pressure in the crankcase, and to provide maximum circulation of ambient air in the crankcase to reduce oil temperatures. The installation of this breather will contribute to increased engine oil life and reduce the possibility of failed engine seals resulting from excessive crankcase pressure.
The included check valve will allow the breather to vent any crankcase pressure that accumulates, but it will not allow ambient air to be drawn back into the engine through the breather under high-vacuum conditions. This valve is beneficial for applications that retain a valve cover vent line, or applications with a very sensitive (or aggressively-lean) PCM calibration.
Note 1: On LSx applications, this breather can be installed in place of the OEM oil cap on top of the factory oil fill tube. With this installation, the factory engine cover (if equipped) can be retained, hood clearance permitting. Our breather can also be installed directly in the factory valve cover without the fill tube for a cleaner look, but there will be interference with the engine cover.
Note 2: This breather stand is also available with a male #10AN connection at the top instead of the provision for the breather element. This configuration is designed for use in a custom crankcase evacuation system or for use with a vacuum pump. Please see Metco Motorsports PN MBR0003-10AN, listed elsewhere in this section. If your vehicle is equipped with aftermarket valve covers using a screw-in thread, please see the MBR0015 breather, also listed elsewhere in this section.
Note 3: Early LS valve covers have only one locating tab in the oil fill tube. With just one tab, the breather can rock slightly when installed. This slight movement is not an issue and the breather will not leak at the base. Later LS covers have two tabs to positively position the breather.
Valve cover breathers cannot ship to the state of California.