Emissions System

When your CPV O-ring fails it causes a slow oil leak on the passenger side of the engine, making an oily mess that frequently resembles a rear main seal leak. Replacing the CPV with an upgraded o-ring ensures a long-term solution to this common problem. 

The factory o-ring over time fails from heat cycling and oil exposure due to the Buna rubber used in OEM o-rings, while the included Viton Fluoroelastomer is resistant to a much higher temperature to ensure prolonged life without leaking. 

Restore proper engine ventilation with this premium replacement Crankcase Breather Valve (11127809512).

Designed to match the performance of the original BMW unit (OE 11-12-7-809-512 / 11-12-7-803-790), this valve maintains correct crankcase pressure, helps prevent oil buildup, and supports clean, efficient engine operation.

Crafted from high-quality, long-lasting materials and shaped to replicate the factory design, it installs easily in place of the stock breather without any modifications required.

Whether you’re addressing pressure-related drivability issues, refreshing your engine’s ventilation system, or performing preventative maintenance, this breather valve provides dependable performance and protects your BMW’s engine for the long haul.

The plastic hoses and oil separator can crack or become faulty, leading to vacuum leaks or oil leaks. This is caused by the stress the plastic components are exposed to during heating and cooling cycles, especially if the vehicle is not brought up to operating temperature during driving in cold weather climates.

This kit includes the needed hoses, oil separator, mounting grommet, and hardware.

Fits the following BMWs:
2000-2003 E39 BMW 530i

Modern day emissions regulations require the use of a closed crankcase ventilation (PCV) system to recirculate combustion blow-by gases from the crankcase back in to the intake to be burned.  Unfortunately, these blow by gases contain water vapor (which is a byproduct of combustion) and pick up oil mist from and the windage cloud and cam lubrication system as they travel through the crank case.  Due to less than 100% effective air/oil separation in the stock PCV system, some oil mist and water vapor gets carried back to the intake tract and over time cause oil deposits and carbon buildup in the intake manifold, intake ports, and on the back of intake valves.  All will eventually lead to poor performance and reduced fuel economy, and the presence oil mist can in the intake charge even increase the risk of engine damaging detonation. 

With direct injected engines this problem becomes more prevalent, and the N54 in your 135i or 335i is no exception.  We're seeing a lot of N54 powered cars with drivability and performance issues due to significant carbon buildup in the intake ports and backs of intake valves.  The “factory fix” is a walnut blasting service that commonly needs performed every 30,000 to 70,000 miles.  Don't be part of this statistic!  Our shop recommends an oil catch can be installed in-line in the PCV system to help reduce the build-up of performance robbing deposits and greatly reduce the need for costly walnut blasting service and related repairs in the future.

The ECS Engineers were able to get more effective results compared to the competition by routing all blow by gasses through the high-load PCV circuit to ensure the catch can is functioning under all engine operating conditions.  The catch can utilizes a strategically designed 4 chamber baffle plate system engineered to create multiple changes in the direction of airflow to cause oil droplets to fall out of suspension, maximizing the efficiency of the PCV air/oil separation.  A dipstick is integrated into the cap so you can monitor the oil level, and the can is easily serviced.  At each oil change simply unscrew the canister and empty the trapped oil with your regular used oil.  The ECS Oil Catch Can is CNC machined from billet 6061-T6 aluminum and with a stealthy black anodized finish for lasting durability and appearance, and includes everything needed for an OEM-like fully reversible installation.  Having a kit designed specifically for your E8X 135i or E9X 335i makes for a clean looking setup that any skill level mechanic can install. 

The ECS Oil Catch Can is made from aluminum and with a stealthy black anodized finish. The location is key as heat will evaporate the oil and send too much vapor back into the engine (where cooler air will turn it back into fluid). The ECS OCC also has a factory-like appearance. Having a kit designed for the E9x 335 makes install easy and clean looking so any skill level mechanic can end up with professional results.

Note: Since the crankcase vent system is considered part of the overall emissions system, installing this may be a violation of local, state, and federal laws. While exemptions are made for track/race and off-road use, check with your local state inspection facility on using this in street-driven vehicles.

*Click here for installation instructions*

ECS Oil Catch Can Features:
+ Increases air intake efficiency
+ Promotes engine longevity
+ 4 chamber design promotes excellent air/oil separation
+ Large In/Out ports (no tapered sizes that slow flow)
+ Anodized black lightweight aluminum
+ Made in USA

This item fits the following BMWs with the N54 twin-turbo engine:
2007-2010 E9X BMW 335i 335xi
 

1.5mm X 51mm Metric Buna-N 70 O-ring is the perfect sealing solution for various industrial applications. Made from high-quality Buna-N material, this O-ring provides reliable sealing performance, ensuring leak-free connections. With its metric sizing and 70 durometer hardness, it offers versatility and durability for a wide range of uses.

• High-quality Buna-N material
• Reliable sealing performance
• Metric sizing for versatility
• 70 durometer hardness for durability

Includes connector housing with terminals and seals. Commonly used for the idle air control valve (IACV).

ECS Tuning replacement harness connectors include all necessary pins and wire seals for a complete harness repair. Whether you have a broken harness connector or need a complete wiring repair, we have the components you need.

Each connector includes an additional terminal in case one becomes lost or damaged during installation.

*OEM cross reference PN# 12521706096 - Commonly used for the idle air control valve (IACV).

Please reference the original part number from the existing connector to confirm fitment, before ordering.

Suggested tools:

Suggested crimping pliers: T#387193
Wire De-pin tools:
12pc De-Pin Tool Set - T#386379
23pc De-Pin Tool Set - T#641943

Ensure your BMW engine runs clean and efficiently with this Crankcase Breather Valve Diaphragm Spring and Cap (11127803790).

A direct-fit replacement for the original BMW breather (OE 11127803790 / 11-12-7-803-790), this valve maintains proper crankcase pressure, reduces oil buildup, and promotes smooth engine performance.

Constructed from durable, high-quality materials and engineered to OEM specifications, it installs easily without any modifications.

Ideal for maintenance, resolving crankcase pressure issues, or restoring your engine’s ventilation system, this breather valve delivers reliable performance and helps protect your BMW for years to come.