BMW N52, N54, & N55 Camshaft Bearing Ledge Wear - An Invisible Disaster

BMW N52/N54/N55 Camshaft Bearing Ledge Wear

The front of the camshafts acts as an oil passage for the VANOS sprockets. If the camshaft’s rectangring seals cut into the camshaft bearing ledge, the wear could be significant enough to allow oil to bypass the seals and leak out. That will cause improper control of the VANOS sprocket, preventing the commanded camshaft position from being achieved.

Oil flowing through the camshafts is controlled by the VANOS solenoids located at the front of the timing cover, so any unexpected oil pressure drops can cause codes related to that issue. Camshaft over-retarded or uncontrollable fault codes will never be fixed by replacing a camshaft position sensor, either. These faults are always mechanical problems that can be misdiagnosed as the camshaft VANOS sprocket or VANOS solenoid.      

BMW Cam Bearing Ledge Wear Fault Codes:

• 2A82 - VANOS intake - stiff; mechanically jammed
• 2A7A - Outlet, Cold Start / VANOS Outlet
• 2A7C - Intlet, Cold Start / VANOS Intlet
• P052D - Cold Start "A" Camshaft Position Timing Over-Retarded
• P05CD - Cold Start "A" Camshaft Position Timing Performance Bank 2
• P0015 - 'B' Camshaft Position Timing Over-Retarded Bank 1
• P0012 - 'A' Camshaft Position Timing Over-Retarded Bank 1
• P1520 - Camshaft Position Actuator 'B' Bank 1
• P1523 - Camshaft Position Actuator Tight or Jammed
• 131501 - VANOS, intake, cold start: not controllable
• 131401 - VANOS, exhaust, cold start: not controllable
• 130104 - VANOS, intake, control fault, camshaft jammed
• 3100 - Boost pressure control deactivation

On N52/N55 engines, the intake cam bearing ledges are part of the Valvetronic bridge, meaning the ledge’s lower half is part of the cylinder head casting. Excessive wear on these surfaces will result in a cylinder head replacement because it is not fixable. N54s do not use Valvetronic, so you can replace the camshaft and tray to retain the cylinder head. All three engines have a separate cam tray for the exhaust side that can be replaced separately if excessive wear is found.

An example of camshaft bearing ledge wear.

Here's a camshaft-bearing ledge with acceptable wear. This engine uses the updated one-piece Teflon seals.

This issue has become so common that BMW issued a service bulletin to help techs in the field identify the causes of VANOS faults:

https://static.nhtsa.gov/odi/tsbs/2012/SB-10032779-8218.pdf

BMW N52/N54/N55 Cam Bearing Ledge Wear Fix

BMW has since updated the cam seals to a single-piece Teflon seal instead of the original metal seal with a split hook design. The change in part numbers is intended to reduce wear and prevent cam tray/cylinder head damage.

The original seal was a metallic split ring design.

The updated one-piece seal is made from a less abrasive Teflon material.

Lower interval oil changes (5K miles) and oil treatments like Ceratec or MOS2 can help reduce this type of wear and extend the service life of your engine. More frequent and regular oil changes are the single best thing you can do to extend the service life of your engine and help reduce oil and VANOS-related issues.