The S54 exhaust hub is a very common failure point and should be checked every 60k miles. The 2 tabs on the hub are prone to breaking off, causing vanos faults and misfires (best case) to engine failure if the one of the tabs falls into the timing chain. In some cases only one tab will fail, which can go unnoticed for a long period of time until the 2nd tab fails, so it's important to visually check the tabs every couple of years. We offer a brand new factory replacement hub that has been cryogenically treated to improve strength by 30% over stock. Cryo-treating is a very involved process which strengthens the metal by cycling the temperature below freezing, then heat treating the part.
The vanos also uses 4 solenoids which are attached to the bottom of the unit in a non-rebuildable aluminum case. These solenoids are very sensitive to oil pressure and can easily become clogged or damaged over time due to contaminates in the oil. Generally this will cause a fault code relating to the vanos and either intake or exhaust timing problems. We highly recommend changing the oil every 5000 miles and only using the BMW 10w60 High Performance oil to prolong the life of the vanos. For the most reliable results we always recommend using NEW factory solenoids over refurbished solenoids. New solenoids will easily last 80-100K miles when the oil is changed regularly.
Typically the S54 vanos does not exhibit the common diesel rattle noise under normal operation. If you notice that your engine has suddenly become noisy we recommend that the car not be driven any more than necessary until the source of the noise can be determined by removing the valve cover, vanos unit and both cam hubs to check all 12 mounting bolts holding each cam gear to the camshaft. These bolts are known to loosen up over time and if left unchecked can fail without warning. In some cases this can cause valve-to-piston interference severely damaging the engine.
The S54 vanos uses a high pressure oil pump located on the back of the vanos unit. This pump, along with the drive hub on the exhaust cam is a potential failure point that may cause extensive damage in a worst-case scenario. Mounted to the front of the exhaust camshaft is a drive hub that spins the oil pump on the back of the vanos unit. The tabs on this hub are known to fail without warning, causing the oil pump on the vanos to stop spinning. Without the high oil pressure needed to drive the cam timing, the engine will misfire at idle and have poor performance. It's common to see several mis-fire codes stored in the DME when this happens. Additionally, the tab failure on the exhaust hub will typically cause excessive wear to the oil pump holes as they bang back and forth, creating excessive play. Our rebuilt S54 vanos units have a modified oil pump to address this potential failure point, and when combined with our cryogenically treated exhaust hub will substantially reduces the chances of pump failures.
To help reduce valve train noise caused by the loose bearings in the splined gears, we offer a set of rebuilt gears with a slight preload on the internal bearings. The gears are offered individually or as a pair, and are sold on a core exchange basis.
Many of our parts are sold on a core exchange basis and require a refundable security deposit for your old parts. This deposit ensures that we receive a good working vanos (or other related part) which can be easily rebuilt and sold to another customer. Once the core is received we will refund the deposit to you within 1-2 business days providing the parts are not broken or damaged in a way other than normal wear and tear. A good rule of thumb is if the parts you are sending back are in more pieces than what we originally sent to you, then they are probably not rebuildable.