Euro S50 Single Vanos
Beisan Systems, LLC and its members provide the following information about the Euro S50 Single Vanos for reference purposes only. However, you should use it at your own risk. Moreover, Beisan Systems, LLC or its members will not be liable for any incidental, consequential, or special loss or damages of any kind, regardless of how they are caused.
Introduction
“Vanos” refers to BMW’s variable valve timing units. These units vary in design depending on the car model and engine year. The specific Vanos covered here is BMW part # 11-31-1-402-428, a single Vanos design. BMW doesn’t offer the diaphragm spring separately for the Euro S50 engine, but it uses the same spring in the S54 and S62 engines.
Like most Vanos systems, this one also can develop a rattle. Specifically , wear in the helical (slanted) gears inside the variable valve timing system causes the rattle. Moreover , these gears are located on the camshaft sprocket and the splined shaft, which attaches to the Vanos. As a result , as the gears wear, the camshaft moves axially, creating free play. Consequently , at certain RPMs, this movement results in a rattle. In fact , the rattle originates from the axial play in the helical gears and splined shaft bearing. Although replacing the helical gears is costly, they will wear again, thus leading to the rattle returning.
Removing axial play from the splined shaft bearing can significantly reduce or even eliminate the rattle. Performance cams, like those in the S50 engine, create stronger camshaft forces, making the rattling more prominent.
Euro S50 Single Vanos
The diaphragm spring in the intake sprocket helps dampen the rattle by controlling the sprocket’s rotational movement. Over time, it weakens and may need replacement to resolve the issue. Although BMW doesn’t offer it separately for the Euro S50 engine, the same spring is used in the S54 and S62 engines. Part numbers are 11-36-7-830-684 for the S54 and 11-36-7-833-218 for the S62. The S62 spring features thicker material for improved performance and longevity.
For further details, refer to the Beisan single and double rattle procedure and the single diaphragm spring procedure.
The splined shaft bearing consists of a washer and two thrust bearings. In order to eliminate axial play, it is necessary to replace or modify some components. Specifically , you can use a hardened bearing steel part and adjust washers for precise axial fit. To facilitate this repair , the Vanos rattle repair kit includes a replacement bearing ring and washers.
Tools, such as a splined shaft holder and socket tool with dowels, are necessary for modification.
Symptoms: The rattle typically occurs between 1800-2200 RPM or at idle.
Repair Procedure
The following is a Euro S50 single vanos splined shaft bearing rattle repair procedure.
This repair should be performed with the Euro S50 single vanos seals repair.
Euro S50 Single Vanos Procedure
Repair time: 1 hour mechanic, 1+ hours DIY.
Parts, Tools, and Shop Supplies
Euro S50 single vanos rattle repair kit (BS032) $40/each (www.beisansystems.com), Euro S50 vanos rattle tool kit (BS094) $20/each (www.beisansystems.com)
4″, or larger, swivel vise
Note: Vise must be mounted for use.
1/2″ impact wrench
For this repair , you will need a few key materials: a magic marker, high-strength thread locker (such as Loctite Threadlocker Heavy Duty (Euro Green, US Red) or Permatex Threadlocker High Strength Red), and 300-400 grit sandpaper (not shown). Once you prepare these materials, you can begin the repair.
Notably, you perform the repair only after removing the Vanos from the engine. To guide you through this process , refer to the Euro S50 single Vanos procedure, which provides detailed instructions. Following that , the next step involves the removal of the intake splined shaft.
First, ensure the TDC (top dead center) timing marks on the engine timing cover and the crankshaft harmonic balancer align, positioned at roughly the 11 o’clock position when viewed in a mirror. If necessary , adjust the alignment using a crankshaft turning socket and a 1/2″ long-arm ratchet. By doing so , you can ensure proper timing before proceeding further.
Verify that the intake camshaft groove on the first guide bearing aligns roughly with the groove on the first bearing cover.
Adjust as needed (24mm open wrench).
First , take note of the amount of intake splined shaft helical gears protruding from the splined shaft housing. Importantly , this measurement serves as a critical reference position for the reinstallation of the splined shaft. Therefore , ensuring accurate documentation of this detail will help facilitate proper alignment during reassembly.
Place open wrench (24mm combo wrench) on intake camshaft hex at front of camshaft.
Rotate intake camshaft counter clockwise until intake splined shaft helical gears fully exist splined shaft housing (24mm open wrench).
If camshaft resistant to rotation rock camshaft back and forth to release seize.
Note: Rotating camshaft is most effective when standing at exhaust side of car.
Only turn camshaft as far as needed for splined shaft to exit housing.
Note intake camshaft cylinder 1 cams will point left and be horizontal.
Draw line on splined shaft housing and splined shaft splines at top position (marker).
This line marks matting of splined shaft and housing helical gears.
Note: This is not necessary but is good practice.
Remove intake splined shaft from housing.
Perform splined shaft rattle kit installation procedure below.
Installation of intake splined shaft
Align intake splined shaft mark with splined shaft housing mark and insert splined shaft into housing and camshaft.
Rotate intake camshaft clockwise while pressing splined shaft into housing (24mm open wrench).
Note: Rotating camshaft is most effective when standing at exhaust side of car.
Splined shaft will insert into housing.
Rotate the intake camshaft using a 24mm open wrench until the groove on the first guide bearing aligns roughly with the groove on the first bearing cover.
Note: Rotating camshaft is most effective when standing at exhaust side of car.
Intake timing is correct if amount of splined shaft helical gears protruding from splined shaft housing is approximately same as before splined shaft removal.
If the helical gears on the splined shaft protrude too much (~10mm) from the housing, you rotated the intake camshaft too far clockwise before mounting the splined shaft.
Repeat above procedure to remove splined shaft and further turn camshaft counter clockwise until cylinder 1 cams point left and are horizontal (24mm open wrench).
Remount splined shaft following above procedure.
If the helical gears on the splined shaft are not protruding from the housing and are inserted too far (~10mm) into the housing, you rotated the intake camshaft too far counterclockwise before mounting the splined shaft.
Repeat above procedure to remove splined shaft then rotate camshaft clockwise until cylinder 1 cams point left and are horizontal (24mm open wrench).
Remount splined shaft following above procedure.
Installation of splined shaft rattle kit
Removal of Splined shaft bearing
Clean splined shaft (brake cleaner & towels).
Remove O-ring at splined shaft stud center (90 degree pick).
Inspect splined shaft bearing axial play.
Hold splined shaft and tilt (rock) splined shaft stud to each side to note bearing axial play (free space).
You can also check axial play by repeatedly inserting and withdrawing the stud into and out of the splined shaft.
Note: Radial play, side to side movement, is normal and necessary. Note that this should not be confused with in/out movement, which is different from axial play.
Open vise jaws as far as necessary to insert splined shaft holder.
Insert splined shaft holder in vise and align top to vise jaw top. Strongly tighten vise on splined shaft holder.
Insert splined shaft in splined shaft holder.
Install splined shaft socket on splined shaft and insert socket pins into splined shaft cover holes.
Note: The socket pins will fit tightly into the splined shaft cover holes, and you may need to rock the socket slightly to fully insert the pins. Make sure to fully insert the socket pins into the splined shaft cover holes and ensure the socket sits completely on the splined shaft cover.
Loosen (break seize) splined shaft cover (splined shaft socket / 1/2″ impact wrench).
If available, set impact wrench power to lowest setting.
Engage impact wrench in reverse for 3 second intervals at a time until cover loosens (seize breaks).
Note: Hold down impact wrench for control.
Remove splined shaft cover (splined shaft socket / 1/2″ ratchet).
Note: Splined shaft cover will turn with difficulty due to thread locker.
The bearing top washer will likely bind to the inner recess of the splined shaft cover and come out with it.
Remove splined shaft center washer / stud (hand).
Note: Splined shaft stud is integral with bearing center washer.
Bearing top thrust (roller) bearing will come out with stud and center washer.
Remove bearing bottom thrust (roller) bearing.
Place pick tip between thrust bearing inner bottom and bottom washer and pry thrust bearing out (90 degree pick).
Remove bearing outer ring.
Place towel on table.
Remove splined shaft from holder, tilt upside down, and hit on towel on table.
Bearing ring will dislodge in splined shaft. Remove bearing ring with index finger.
If bearing ring tilts and binds in splined shaft, press ring down in splined shaft to remount, then reattempt removal.
Reinstall splined shaft in splined shaft holder.
Remove bearing bottom washer.
Place pick tip between washer inner bottom and splined shaft and pry washer out (90 degree pick).
Cleaning of parts
Clean bearing parts (brake cleaner & towels).
Note: It is crucial to thoroughly clean all bearing parts, as this step is necessary for properly assessing the new bearing’s axial fit.
Remove old thread locker from cover and housing thread. Use pick tool to press tip into thread valley and run pick throughout thread (90 degree pick).
Note: It is critical to fully remove old thread locker so that new thread locker can bond properly with the parts.
Clean splined shaft bearing cavity and cover (brake cleaner & towels).
Installation of splined shaft bearing
Replace bearing ring and top and bottom washers with new parts.
Bearing parts installation sequence from right to left.
Bearing parts from left to right: Cover, top washer, top thrust bearing, center washer / stud, bottom thrust bearing, bottom washer, bearing ring.
Insert new bearing ring in splined shaft (fingers).
Note: The manufacturer marks the new ring with “BS” on its outer perimeter.
Initially insert ring in splined shaft.
Insert right and left index fingers into ring. Press fingers against ring inner right and left walls and manipulate ring side to side while slightly pressing down to facilitate ring full insertion.
Rotate position of fingers 90 degrees and repeat ring insertion to verify full insertion.
Note: Ring should fully mate with splined shaft bottom. (picture).
Insert bearing bottom washer in splined shaft bearing ring.
Note: Splined shaft bearing top and bottom washers are interchangeable. Note: Both faces of the washer are identical, so it can be inserted in either orientation.
Insert bearing bottom thrust (roller) bearing in splined shaft bearing ring.
Note: Splined shaft bearing top and bottom thrust bearings are interchangeable. The thrust bearing faces are functionally identical, so you can insert the thrust bearing in either orientation.
Insert bearing center washer / stud in splined shaft bearing ring.
Insert bearing top thrust (roller) bearing onto splined shaft stud and in splined shaft bearing ring.
Note: The thrust bearing faces are functionally identical, so you can insert the thrust bearing in either orientation.
Insert bearing top washer in splined shaft cover inner cavity.
Apply some oil to splined shaft cover inner cavity.
Insert bearing top washer in cover cavity.
Note: Washer will bind to cover due to oil.
Note: Mounting bearing top washer to cover inner cavity allows for cover installation without bearing top washer interference.
Install splined shaft cover with bearing top washer onto splined shaft (splined shaft socket / 1/2″ ratchet).
When you install the splined shaft cover, its top should align evenly with the splined shaft rim (see picture). If the cover sits higher than the rim, the bearing parts are not installed correctly and are interfering with the cover installation.
Remove cover and reinstall bearing parts.
Fully tighten splined shaft cover, 55 Nm (40.5 ft-lb) (splined shaft socket / 3/8″ torque wrench & 3/8″ to 1/2″ socket adapter).
Inspection and adjustment of splined shaft bearing
Inspect splined shaft bearing axial play.
Hold splined shaft and rotate splined shaft stud to note resistance to rotation.
Hold splined shaft and tilt (rock) splined shaft stud to each side to note bearing axial play (free space).
Note: Axial fit cannot be properly assessed until splined shaft cover is fully tightened.
Note: Radial play, side to side movement, is normal and necessary.
This should not be confused with axial play , which refers to in-and-out movement.
- If the splined shaft stud binds or is difficult to rotate, the axial fit is too tight, and loosening the adjustment is necessary .
- If the splined shaft stud has any tilt movement, axial play is present, and tightening the adjustment is required .
- Any level of resistance (pre-load) in the splined shaft stud’s rotation—without binding —indicates that there is no axial play, which is considered an optimal fit .
Bearing loosening adjustment.
If splined shaft binds and is difficult to rotate then axial fit it too tight and loosening adjustment is needed.
Disassemble splined shaft bearing per above procedure.
Place sandpaper (300-400 grit) on flat table top. Place bearing outer washer on sandpaper.
Slide washer side to side on sandpaper ~6″ back and forth while moderately pressing washer on sandpaper. Perform sanding for 10 seconds.
Rotate washer 90 degrees and repeat sanding process.
Flip washer to opposite side and repeat above sanding procedure; 10 seconds sanding, rotate 90 degrees, 10 seconds sanding.
Clean washer (brake cleaner & towels).
Repeat washer sanding for second outer washer.
Reassemble splined shaft bearing per above procedure and reassess bearing axial fit.
Note: Washers are made from hardened steel and do not easily wear. Sanding procedure will remove ~.0025mm washer height, total ~.005. Washers might need max .015mm height adjustment.
Bearing tightening adjustment.
If splined shaft has any tilt movement then axial play is present and tightening adjustment is needed.
Disassemble splined shaft bearing per above procedure.
Place sandpaper (300-400 grit) on flat table top. Place bearing ring on sandpaper.
Slide ring side to side on sandpaper ~6″ back and forth while moderately pressing ring on sandpaper. Perform sanding for 5 seconds.
Rotate ring 90 degrees and repeat sanding process.
Flip ring to opposite side and repeat above sanding procedure; 5 seconds sanding, rotate 90 degrees, 5 seconds sanding.
Clean ring (brake cleaner & towels).
Reassemble splined shaft bearing per above procedure and reassess bearing axial fit.
Note: Ring is made from hardened steel and does not easily wear. Sanding procedure will remove ~.005mm ring height. Ring might need max .015mm height adjustment.
Once splined shaft bearing fit is assessed, and if needed adjustment performed, thread locker needs to be applied to splined shaft cover.
Remove splined shaft cover from splined shaft per above procedure.
Apply thread locker at middle of threads along perimeter of cover (high strength thread locker).
Reinstall splined shaft cover and fully tighten per above instructions.
Reinstall splined shaft stud O-ring.
Insert O-ring on splined shaft stud and roll O-ring down stud and drop into groove (fingers).
Verification of engine timing
Perform following engine timing verification once vanos has been reinstall on engine head and just before vanos solenoid installation.
Turn crankshaft pulley clockwise for two revolutions (crankshaft turning socket / 1/2″ long-arm ratchet).
If crankshaft binds and can’t be turned this is due to valve/piston interference and indicates timing is set wrong.
Turn crankshaft pulley clockwise until cylinder 1 intake and exhaust cams point to each other at ~45 degree angle (crankshaft turning socket / 1/2″ long-arm ratchet).
Note: Turning crankshaft counter clockwise is acceptable.
Inspect TDC (top dead center) timing marks on engine timing cover and crankshaft harmonic balancer at ~11 o’clock position (mirror).
Adjust crankshaft pulley to align TDC timing marks (crankshaft turning socket / 1/2″ long-arm ratchet).
Note: Align pointer on timing cover with 1 mark on harmonic balancer.
Note: If timing marks on harmonic balancer not visible they might be hidden behind water pump pulley. Turn crankshaft pulley counter clockwise.
Note: Precise alignment is not necessary.
Exhaust camshaft groove on first guide bearing will be roughly aligned with groove on first bearing cover (picture).
Fully retard intake camshaft timing.
Place open wrench (24mm combo wrench) on intake camshaft hex at front of camshaft.
Rotate intake camshaft counter clockwise to adjustment end position. If camshaft resistant to rotation rock camshaft back and forth to release seize.
Note: Rotating camshaft is most effective when standing at exhaust side of car.
Camshaft groove on first guide bearing will be roughly aligned with groove on first bearing cover (picture).
If intake or exhaust camshaft timing grooves do not align within small deviation then engine timing it set wrong.
© 2025 Beisan Systems LLC