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Oil Separation & Breather System

Every car has a crankcase vent system that is supposed to suppress oil from making it into the intake ports and combustion chamber. A good functioning system will separate oil from the atmosphere and return it to the oil pan (or collect it in a catch can) while allowing the leftover vapors to burn in the combustion chamber or recirculate through the system. This has always been known as a PCV system (Positive Crankcase Ventilation) but BMW has several other names for it - oil separator, crankcase vent (CCV), and cyclonic separator. Failures in the system will allow raw oil to enter the intake and eventually into the engine itself which can have disastrous effects on engine performance and longevity. As emissions regulations on oil and gas venting have gotten more stringent the PCV systems have gotten more complex and failure prone. And because the CCV is intertwined with other systems you could experience rough running, loss of power, higher oil consumption, misfiring, stalling, or other annoying issues. There is no replacement interval for these so we recommend inspecting your crankcase vent system as part of your regular maintenance routines. Symptoms of a bad crankcase vent are: whitish or yellowish film on the underside of the oil cap, whistling/squealing noises (not caused by a belt), suction on the oil cap that makes it hard to unscrew, large amounts of white smoke from the exhaust, and excessive oil consumption.

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CCV/PCV Breather Hoses (6)

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Comprehensive Constant Pressure Valve Replacement Kit

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T#:557341

Part#: 11111318185TMSKT

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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.

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Bav Auto Crankcase Pressure Regulator Valve - BMW M52 M54

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T#:640207

Part#: 11617501566

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BMW has an ongoing issue with oil separators freezing in cold weather if driving is done before the vehicle is fully warmed up. There is often a howling noise followed by numerous oil leaks. The crankcase breather valve is used to purge the oil vapor from the engine block into the valve cover. However, sometimes condensation can cause it to freeze, causing the entire oil separator system to fail, crack, and disintegrate. Replace this and all the other components of the oil separator system to prevent damage to all the aspects of your engine. As long as you have everything off, you can rest assured that new parts will last and be reliable. From 1974 to 2019, Bavarian Autosport was one of the premier vendors for BMW and MINI auto parts. We are happy to preserve the Bav Auto legacy by continuing to carry their high-quality products into the future. All Bav Auto parts will remain unchanged in design and sourced from the same OEM suppliers to ensure long-lasting reliability. We trust these parts, accessories, and upgrades so confidently that we back every Bavarian Autosport branded component with a 2-year warranty.

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Bav Auto Crankcase Ventilation Return Hose - E46 E39 E60 Z3

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T#:638072

Part#: 11617504536

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This is the BMW crankcase return line that goes from the intake manifold to the top CCV connecting hose. From 1974 to 2019, Bavarian Autosport was one of the premier vendors for BMW and MINI auto parts. We are happy to preserve the Bav Auto legacy by continuing to carry their high-quality products into the future. All Bav Auto parts will remain unchanged in design and sourced from the same OEM suppliers to ensure long-lasting reliability. We trust these parts, accessories, and upgrades so confidently that we back every Bavarian Autosport branded component with a 2-year warranty.

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Crank Case Vent Hose Kit - S63 4.4L Engine

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T#:23913949

Part#: CRNKVENTKITKT

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$ 223.99

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Elevate your S63 4.4L engine's capabilities with our meticulously designed Crank Case Vent Hose Kit. Crafted from premium-grade materials, this kit ensures superior ventilation, mitigating pressure accumulation within the engine, thereby enhancing its overall performance.

Engineered to precise specifications, our kit seamlessly replaces the OEM vent hoses, guaranteeing a perfect fit. By reducing stress on the engine, it prolongs its lifespan and maintains peak functionality. Rely on this kit to provide unparalleled performance and unwavering reliability for your S63 4.4L engine.

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Bav Auto Vent Hose - From Valve Cover to Oil Separator - E36 E39 Z3 ...

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T#:579869

Part#: 54546

Ships on Aug 31, 2026

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Performance Oil Separator Kit - M52/S52

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T#:51356040

Part#: 059015LA02KT2KT

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On M52/S52-equipped BMWs, the factory crankcase ventilation (CCV) system is a notorious weak link. Between brittle plastic corrugated hoses that crumble from heat soak and an internal cyclone diaphragm prone to tearing, a failing CCV leads to massive oil consumption, vacuum leaks, and that dreaded "howling" whistle.

This kit addresses these issues with all new components and hardware. Both oil separator hoses, the cyclone separator itself, the mounting grommet, and the retaining bolts are included. Servicing this system is guaranteed to restore performance lost as a result of worn CCV components.

Kit includes:

Cyclone Separator/Crankcase Pressure Regulator Valve High Performance Silicone Breather Hose Return Hose Mounting Grommet Hex Bolt (3)

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Bav Auto Crank Case Ventilation Valve - E31 E38 E39 M62 4.4L ...

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T#:640206

Part#: 11617501563

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$ 38.39 USD

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An integral part of the emissions system, the PCV valve lets the crankcase breathe. This allows proper intake and exhaust flow, resulting in proper running and operation. When the crankcase vent valve fails it can cause excessive oil consumption, engine fault codes, and poor idle. From 1974 to 2019, Bavarian Autosport was one of the premier vendors for BMW and MINI auto parts. We are happy to preserve the Bav Auto legacy by continuing to carry their high-quality products into the future. All Bav Auto parts will remain unchanged in design and sourced from the same OEM suppliers to ensure long-lasting reliability. We trust these parts, accessories, and upgrades so confidently that we back every Bavarian Autosport branded component with a 2-year warranty.

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Engine Oil Separator Package - Level 2 - E46 325, E39 525i M54 ...

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T#:24344785

Part#: M54OILSEPKT

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$ 130.12 USD

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If you need to perform a complete oil separator system service, this Level 2 kit provides you with all of the main components necessary to service your engine oil separator system. This Level 2 kit includes the following: Oil Separator Hose from oil separator to dipstick tube Hose from oil separator to valve cover Hose from intake manifold back to the connector hose Hose from oil separator up to the intake manifold Throttle body gasket Throttle body inlet boot ICV rubber grommet Oil dipstick tube o-ring seal It is highly recommended to replace the oil dipstick tube with the updated design by BMW as this also a common place for sludge to build up.

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Turner Oil Separator Kit - E39 M54

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T#:555298

Part#: 11617501566KT6

Ships on Jul 6, 2026

Sale - Save 20% $ 181.99

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$ 144.82 USD

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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

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Bav Auto Intake Manifold Cover w/ PCV Valve - BMW E31 E32 E34 E38 M6...

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T#:639843

Part#: 11617501562

Special Order: No Guaranteed ETA

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$ 50.99 USD

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An integral part of the emissions system, the PVC valve lets the crankcase breathe. This allows proper intake and exhaust flow, resulting in proper running and operation. Often split from underhood heat and age, this vents excess oil into the engine compartment. From 1974 to 2019, Bavarian Autosport was one of the premier vendors for BMW and MINI auto parts. We are happy to preserve the Bav Auto legacy by continuing to carry their high-quality products into the future. All Bav Auto parts will remain unchanged in design and sourced from the same OEM suppliers to ensure long-lasting reliability. We trust these parts, accessories, and upgrades so confidently that we back every Bavarian Autosport branded component with a 2-year warranty.

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Turner Oil Separator Valve Service Kit - E39 M5

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T#:555299

Part#: 11151406788KT3

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$ 323.99 USD

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The rubber hoses and oil separator can crack or become faulty, leading to vacuum leaks or oil leaks. This is caused by the stress the 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:
1998-2003 E39 BMW M5

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Oil Separator Hose - E46, Z4

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T#:579880

Part#: 55080

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Sale - Save 20% $ 24.99

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$ 19.99 USD

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Cold climate version for extra insulation! Fits all E46 and Z4 chassis equipped with an M54 engine.

Bav Auto Upper Oil Separator Vent Tube - E36 E46 E60 E84 Z3 Z4 M54 M5...

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T#:640502

Part#: 11617504535

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$ 19.99 USD

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Runs from the top of the oil separator up to rear of the intake manifold. From 1974 to 2019, Bavarian Autosport was one of the premier vendors for BMW and MINI auto parts. We are happy to preserve the Bav Auto legacy by continuing to carry their high-quality products into the future. All Bav Auto parts will remain unchanged in design and sourced from the same OEM suppliers to ensure long-lasting reliability. We trust these parts, accessories, and upgrades so confidently that we back every Bavarian Autosport branded component with a 2-year warranty.

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Crankcase Oil Separator and Vent Hose Kit - E90 325xi/330xi, E60 525x...

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T#:221962

Part#: TMS221962

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$ 453.99

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03-04-2026

$ 450.99 USD

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The BMW N52 engine was deisgned with a crankcase vent system that relies on a heated oil separator valve to separate vapor from the liquid oil. Under ideal circumstances, the oil vapor would pass back into the intake and get burned up during normal combustion. The liquid oil would follow a path back down into the oil pan and be reused. This system is environmentally friendly but plagued with problems. The heating elements can fail or oil and carbon particles can block the oil separator valve. With no escape, the oil will continue to pool and collect in the valve cover or make its way into the combustion chamber leading to excessive oil consumption, blue smoke from the exhaust, idle and running issues. These issues are worse in colder climates where the freezing temperatures create an oil sludge condition that is impossible to clear. The plastic hoses can become brittle and crack which leads to vacuum leaks and oil leaks. Thankfully, the CCV is replaceable on the early N52 engines (2006 and some 2007 models) and should be inspected during a major service and any time the valve cover is off. Oil can also back up into the throttle body, which is easier to check than the oil separator itself. Later N52 engines do not have a serviceable oil vent as it is integrated into the valve cover and not a separate part.

This is a kit containing the oil separator, the vent hoses, and the intake manifold gaskets that are done during a typical oil separator replacement. Complete kit includes:

11617531423, Genuine BMW oil separator

11617559530, vent hose

11157522931, oil separator hose

11157567801, return hose

11157537701, extraction hose

11617547242, intake manifold gaskets (set of 6)
The intake manifold must be removed to access the oil separator so new profile gaskets are included. We also recommend (but not required) a new oil separator fitting on the intake manifold because it's one of the heated elements that vaporizes the oil as it enters the intake.

The oil separator can be replaced on its own but for a complete service we also recommend replacing the oil separator hoses and cleaning the valve cover. Any valve cover or intake manifold work should include a new oil separator valve.

This kit fits the following BMWs:
-10/2005 E90 BMW 325xi 330xi - Sedan
-10/2005 E91 BMW 325xi - Wagon
-10/2005 E60 BMW 525xi 530xi

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Turner Emissions Service Kit - E46 M3

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T#:555304

Part#: 11157840446KT9

Ships on Sep 28, 2026

$ 406.99

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$ 405.99 USD

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The 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, and hardware.

Fits the following BMWs:
09/2004-2006 E46 BMW M3 - Manual Transmission

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Turner Emissions Service Kit - E46 M3

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T#:555305

Part#: 11157840446KT10

Ships on Sep 28, 2026

$ 278.99 USD

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The 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, and hardware.

Fits the following BMWs:
2001-09/2004 E46 BMW M3 - Manual Transmission

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Turner Oil Separator Kit - E53 X5 M62 4.4L 4.6L

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T#:555308

Part#: 11151705237KT1

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01-03-2026

$ 202.52 USD

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$ 202.52 USD

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The rubber hoses and oil separator can crack or become faulty, leading to vacuum leaks or oil leaks. This is caused by the stress the 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, and hardware.

Fits the following BMWs:
1999-2006 E53 BMW with M62 4.4L 4.6L

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Oil Separation & Breather System
- CCV/PCV Breather Hoses (6)

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