The sound of marbles in a can is a disappointing noise that many BMW M5x owners have heard to their dismay. Fortunately, the Vanos rebuild provided by ECS will refresh your Vanos components and reseal your Vanos unit. Below you will find instructions for our Vanos refresh DIY with kits supplied by ECS. You can purchase all tools and parts mentioned in this post by following the bold names of parts or tools.
• 1/2” Drive Ratchet
• 1/2” Drive Extensions
• 1/2” Drive Impact Wrench
• Air Nozzle/Blow Gun
• Bench Mounted Vise
• Crows Foot Wrenches
• 1/4” Drive Torque Wrench
• Ball Pein Hammers
• Electric/Cordless Drill
• Wire Strippers/Crimpers
• Adjustable (Crescent) Type Wrenches
• Drill Bits
• Punch and Chisel Set
• 400 Grit Sandpaper
• Exacto Knife
Standard Shop Supply Recommendations: We recommend that you have a standard inventory of automotive shop supplies before
beginning this or any automotive repair procedure. The following list outlines the basic shop supplies that we like to keep on hand. Shop
supplies listed below in bold are links and will take you to our recommended products.
• Aerosol Brake/Parts Cleaner – for cleaning and degreasing parts
• Shop Rags – used for wiping hands, tools, and parts
• Penetrating oil – for helping to free rusted or stuck bolts and nuts
• Mechanics wire – for securing components out of the way
• Silicone spray lube – for rubber components such as exhaust hangers
• Paint Marker – for marking installation positions or bolts during a torquing sequence
• Plastic Wire Ties/Zip Ties – for routing and securing wiring harnesses or vacuum hoses
• Electrical tape – for wrapping wiring harnesses or temporary securing of small components
RH refers to the passenger side of the vehicle.
• LH refers to the driver side of the vehicle.
• Always use the proper torque specifications.
• If applicable to this installation, torque specifications will be listed throughout the document and at the end as well.
• Please read all of these instructions and familiarize yourself with the complete process BEFORE you begin.
ECS Tuning cares about your health and safety. Please read the following safety information. This information pertains to automotive service
in general, and while it may not pertain to every job you do, please remember and share these important safety tips.
• Park your car in a safe, well lit, level area.
• Shut the engine off and remove the key from the ignition switch.
• Make sure any remote start devices are properly disabled.
• ALWAYS wear safety glasses.
• Make sure the parking brake is applied until the vehicle is safely lifted and supported.
• If using an automotive lift, be sure and utilize the factory specified lift points. Lifting a vehicle in an incorrect location can cause damage to the
• suspension/running gear.
• When lifting a vehicle using a jack, always utilize the factory specified lift points. Lifting a vehicle in an incorrect location can cause
• damage to the suspension/running gear. ALWAYS support the vehicle with jack stands.
• ALWAYS read and follow all safety information and warnings for the equipment you are using.
The Dual Vanos unit on an M5x engine is mounted on the front of the
cylinder head where the Vanos pistons can connect to the ends of the
camshafts. Unlike some, this Vanos unit can be easily unbolted without
affecting the engine timing in any way, making it one of the simplest
Since getting to the Vanos unit only requires some basic component
removal which we’re sure you can handle, we’re not actually going to
cover the step by step process, but we will give you a quick outline of
what you have to remove:
1. Remove the radiator fan and shroud.
2. Remove the cabin filter housing.
3. Remove hoses/harnesses around valve cover perimeter.
4. Disconnect ignition coils and move the harness out of the way.
5. Remove ignition coils.
6. Remove the valve cover.
Once you have the valve cover removed, you’ll see the Vanos unit.
Remove the items we’ve listed below (we’ve placed the step numbers in
their approximate locations), then proceed to the next page to remove the
The M5x Dual Vanos unit is just under the valve cover at the front
1. Remove the Vanos oil hose.
2. Remove the engine lift bracket.
3. Disconnect the Vanos exhaust cam sensor.
4. Disconnect the Vanos exhaust solenoid.
5. Disconnect the Vanos intake solenoid.
6. Disconnect the thermostat electrical connector.
A lot of oil will be lost during these steps, so be sure to catch as much as possible and
cover the drive belts as well as the accessories to keep them clean.
To remove the Vanos unit, first you must remove the piston access plugs with an 8mm
Allen socket. Second, pull out the two piston caps using needle nose pliers. Third,
remove the two splined shaft bolts using a T30 Torx – these are LH (reverse) thread so
don’t be fooled.
With the pistons unbolted from the splined shafts, you’re ready to remove the entire
Vanos unit. All that remains are six nuts and one bolt. Remove the nuts using a 10mm
socket, then remove the bolt using a 13mm socket. Now you can pull the Vanos unit off
the front of the engine, and it’s time to start the rebuild.
With the Vanos unit removed from the engine, familiarize yourself with it before taking it apart. Rest it on a bench so you are looking at the cover
plates for the Vanos cylinders. Viewed from this side, the Intake cylinder is on the left, held on by five bolts, and the Exhaust cylinder on the right, held
on by four bolts.
We recommend marking the Intake and Exhaust pistons with an “I” and an “E”, using a permanent marker. They are the same, and even though they are
interchangeable, the best practice is to reassemble all components where they were originally located, since they may wear in differently with the parts
they are in direct contact with.
Remove the cover plate bolts and disassemble the Vanos
unit. As you remove the cover plate bolts for the exhaust
cylinder, the spring behind the piston will push the
cover plate off. It’s best to hold down on the cover plate
and remove the bolts, then allow the spring to push
everything up. This will remove any possibility of spring
tension causing thread damage as the bolts are removed.
Lay everything out and keep it organized as we
have done below.
Thoroughly clean all parts, using extra care not to bend
or distort the metal cover plate gaskets. These will be
Using an exacto knife, carefully cut the original Teflon seals and o-rings
out of each piston. There will be two seals and two o-rings on each
The original Teflon seals and o-rings will be difficult and dangerous to
remove with any other type of device other than the fine tip of an exacto
knife. Be careful not to score or scratch the surface or the grooves of the
Make sure that both pistons have been thoroughly cleaned and that the
seal and o-ring grooves are clean all the way around. Now, notice the
large hex on the end of each piston, this is the piston cap. Before we
install the new seals and reassemble the Vanos, we have to install the new
bearing rings. There is one inside each piston, and we’ll remove the piston
caps to get to them.
The actual Vanos “rattle” is caused by axial play in the bearings which are housed inside the piston. The key to solving this problem is to remove the
axial play (tighten), and ideally, provide a slight preload on the roller bearings. To accomplish this, you’ll check the amount of play, install the new ECS
bearing rings in place of the originals, then recheck the amount of play. Due to very strict tolerances and the different rates of component wear from car to car, some fine tuning may be required.
When the Vanos piston is mounted onto the end of the splined shaft, any in and out movement is axial play. This measurement is strictly determined by “feel” and is easily detectable. The key is holding the splined shaft stationary with one hand (they will move a little if you don’t), and gently moving the piston in and out with the other. Side – to – side, or radial play, which is felt by moving the piston left and right in relation to the splined shaft, is normal.
This illustration shows the cause of axial play in the bearings. There is clearance between the roller bearings, the bearing race, and the end washers. The bearing ring in this case is, in effect, too wide. The clearance is eliminated by decreasing the width of the bearing ring until all axial play is removed.
In this illustration, the bearings would be too tight. The bearing ring in this case is, in effect, too narrow. When the piston is assembled, the end washers will “crush” the bearings as they attempt to seat against the bearing ring. In this situation, since you cannot increase the width of the bearing ring, to solve the problem you would decrease the width of the bearing race.
Now that you understand the theory, we’ll get back to it. The picture on the right shows the splined shafts in the end of each camshaft. This is where each of the Vanos pistons is secured with a T30 splined shaft bolt. One at a time, we’re going to mount the Vanos pistons onto the end of the intake cam and check for axial play. We’re using the intake cam simply because the splined shaft is easier to get to.
Now, install one of the pistons onto the end of the intake camshaft and tighten the bolt slightly using a ratchet. You do not need to fully tighten or torque the bolts, they only need to be tight enough to securely hold the bearing race to the splined shaft. A loose bolt here would feel like axial play and throw off your adjustment.
Now it’s time to check for axial play in the Vanos piston. First, using one hand, hold the splined shaft to keep it from moving. Next, follow the flow chart below to check and adjust axial play/ preload of the Vanos pistons.
The piston cap must be removed so we can get to the components inside. You’ll have to hold the piston in a vise, and there are only a couple safe ways of doing this. You must not damage or distort the piston in any way, or it will be ruined, so be careful. If you have nylon vise jaws, they will work perfect, and the only other alternative is a couple pieces of wood as we have done here.
Once the piston is securely held, use an impact wrench to loosen the piston cap. It’s not actually that tight, but you’ll find that the piston will still rotate slightly in the vise jaws, and it’s the rapid shock of the impact that will loosen it. If it doesn’t loosen at first, tighten the vise to limit spinning as much as possible and give the nut multiple “blips” with the impact.
Once you have removed the piston cap, remove the individual components and lay them out in order. Clean everything thoroughly – if these aren’t spotless it can throw off your axial play/preload – then locate the bearing race and the bearing ring.
If this is the initial installation of the bearing ring, remove the original bearing ring from the line up and replace it with the new one. If you have already installed the new bearing ring and are adjusting the bearing ring clearance, go to the ring clearance instructions above. If you have already installed the new bearing ring and are adjusting the bearing race clearance, go to the bearing race clearance instructions above.
To tighten the bearing (when axial play or no preload is present) – sand the bearing ring using the following procedure:
1. Place a sheet of 400 grit sandpaper on a solid, flat surface.
2. Using medium pressure, sand one surface of the ring back and forth 6-8”, approximately 30-40 times.
3. Rotate the ring 90 degrees, and repeat the sanding procedure.
4. Flip the ring over and repeat the sanding procedure.
5. Rotate the ring 90 degrees and repeat the sanding procedure.
This procedure will remove a very small amount of material, approximately .004 – .006mm from the total thickness of the ring.
Thoroughly clean the bearing ring and continue
To loosen the bearing (when excessive force is required to rotate piston) – sand the bearing race using the following procedure:
1. Place a sheet of 400 grit sandpaper on a solid, flat surface.
2. Using medium pressure, sand one surface of the race back and forth 6-8”, approximately 30-40 times.
3. Rotate the race 90 degrees, and repeat the sanding procedure.
4. Flip the race over and repeat the sanding procedure.
5. Rotate the race 90 degrees and repeat the sanding procedure.
This procedure will remove a very small amount of material, approximately .004 – .006mm from the total thickness of the race.
Thoroughly clean the bearing race and continue
Reassemble the Vanos piston using the new bearing ring. Make sure all components are fully seated, then thread the piston cap in by hand until it too is fully seated.
Once the piston is assembled, secure it again in the vise with protective jaws, then use the impact wrench to tighten the piston cap. It doesn’t have to be excessively tight, a few “blips” with the impact is all it takes.
Carefully install the new rubber o-rings into the piston grooves, making sure they are not twisted.
Warm the new Teflon seals in hot tap water, then carefully install them by starting them in the groove on one side of the piston, seating them all the way around as far as possible, then stretching them over the opposite edge with your fingers. Once they are fully seated, allow them to cool for a few minutes to return to their normal size.
Coat the Teflon seals with clean engine oil.
Prepare to reassemble the Vanos unit. Make sure you locate the intake and exhaust pistons on the correct side, and place the spring into the Vanos housing on the exhaust side.
Place the metal gaskets onto their corresponding Vanos cylinder cover plate, then coat the bore of each cover plate with clean engine oil.
Gently push each piston into its corresponding cover plate, rocking it back and forth gently as required so the Teflon seal seats easily into place.
Install the intake cover plate and piston, gently rocking the piston back and forth as necessary to guide it into the piston bore.
Install the exhaust cover plate and piston, again gently rocking the piston back and forth as necessary to guide it into the piston bore. You will have to work against the spring tension on this piston, and once it is installed, hold the cover plate against the Vanos housing, and install the bolts.
Install the intake cover plate bolts as well, then torque them all in an alternating fashion to 10 Nm (7 Ft-lbs).
Just to double check the operation, push the pistons in and out to make sure they operate smoothly. The exhaust will require additional effort to overcome the spring tension.
You’re almost ready to reinstall the Vanos unit. Remember the piston caps you pulled off? The o-rings are no doubt shot, just like the one in the LH photo, so we’ve included new ones. If you purchased a hardware or refresh kit, you’ll have new caps w/o-rings. If not, remove the old o-rings, – you may have to use an exacto knife – then clean up the piston caps and install the new 9mm o-rings.
Installing the rebuilt Vanos unit is as easy as taking the old one off, but here’s a few points about the job:
• Be sure and clean all surfaces thoroughly before reinstalling components.
• Be sure to use a new Vanos unit gasket.
• Push the Vanos Intake piston all the way into the Vanos unit to make installation easier.
• Torque all fasteners to the proper specification.