Genuine BMW E23 E24 E28 M30 Auxiliary Air Bypass Housing – 11631271342

Original used BMW auxiliary-air bypass housing for selected BMW E23, E24 and E28 models equipped with an M30 petrol engine.

This aluminium housing forms part of the engine’s auxiliary-air and cold-idle system. It connects and routes the relevant air hoses used together with the auxiliary air slide valve.

The housing carries casting number 1 271 344. The corresponding BMW catalogue number is 11631271342.

This is a passive aluminium housing without electrical or moving components. Several similar housings and hose arrangements were used depending on the vehicle model, production date and country specification.

Product details

• Product: Auxiliary-air bypass housing
• Alternative description: Air bypass hose connector
• German description: Umleitgehäuse
• Manufacturer: Genuine BMW
• BMW part number: 11631271342
• Formatted BMW number: 11 63 1 271 342
• Short BMW reference number: 1271342
• Casting number: 1 271 344
• Compact casting number: 1271344
• Engine family: BMW M30
• Number of hose connections: Three
• Material: Cast aluminium
• Mounting bracket: Integrated
• Installation position: Engine intake and auxiliary-air system
• Condition: Used
• Quantity: One

Vehicle compatibility

Suitable for selected M30-powered BMW models using the corresponding auxiliary-air hose system.

BMW 5 Series E28

• BMW 525i
• BMW 528i

BMW 6 Series E24

• BMW 628CSi
• BMW 633CSi
• BMW 635CSi

BMW 7 Series E23

• BMW 728i
• BMW 728iS
• BMW 732i
• BMW 733i
• BMW 735i
• BMW 745i with the corresponding M30 intake system

Compatibility depends on the model, production date, engine version, transmission, emissions equipment and country specification.

Certain Australian, Swedish, Swiss and other market-specific vehicles used different auxiliary-air valves, hoses or connection arrangements. Always compare the BMW part number, casting number, mounting point and all three hose connections with the original component before ordering.

BMW and casting numbers

• 11631271342 – BMW auxiliary-air bypass housing
• 11 63 1 271 342 – Formatted BMW catalogue number
• 1271342 – Short BMW catalogue reference
• 1 271 344 – Casting number visible on the housing
• 1271344 – Compact casting reference

The casting number is not identical to the BMW catalogue number. The part should be ordered and identified primarily using BMW number 11631271342.

Function

The housing connects the hoses in the auxiliary-air bypass circuit. During cold operation, additional air can be routed around the closed throttle through the auxiliary air slide valve, helping the engine maintain a higher and more stable cold-idle speed.

The exact hose arrangement varies between different models and production periods. This listing includes only the aluminium bypass housing.

Condition

Original used BMW component with visible age- and use-related wear, including:

• Dirt and storage marks
• Aluminium oxidation and surface discolouration
• Deposits inside and around the hose connections
• Marks from previously fitted hoses and clamps
• Cosmetic wear around the mounting point
• General wear consistent with an original classic BMW engine component

No cracks are clearly visible in the photograph, but the housing has not been pressure- or leak-tested.

The housing should be thoroughly cleaned and inspected before installation. Supplied exactly as shown in the photograph.

Included

• One original BMW auxiliary-air bypass housing
• Integrated mounting flange

No hoses, hose clamps, auxiliary air slide valve, O-ring, gasket, mounting bolt or other installation hardware are included.

Installation recommendation

Before installation:

• Thoroughly clean all internal passages
• Remove corrosion and old hose deposits carefully
• Inspect the aluminium housing for cracks or porosity
• Check all hose connections for deformation or damage
• Compare the hose diameters and orientation with the original housing
• Use suitable replacement hoses and clamps
• Replace any required seal or O-ring
• Check the complete auxiliary-air system for vacuum leaks after installation

Air leaks in this system may cause an excessively high, low or unstable idle speed. Installation should preferably be carried out by someone familiar with classic BMW M30 intake systems.

Storage location: 203