Single Vanos 6-cyl (E36, E34, E39)

6-cylinder Single Vanos Procedure (E36, E34, E39)  

The following information is provided for reference purposes only and should be used at your own risk Single Vanos system
In no event shall Beisan Systems, LLC or its members be liable for incidental, consequential, or special loss or damages of any kind however caused.

Introduction

“Vanos” is BMW”s name for its variable valve timing units. Vanos units take on various shapes and design according to car year and model (engine model). The vanos discussed here is BMW part # 11-36-1-748-036 (M50TU, US S50) and 11-36-1-748-819 (M52, S52). It”s a single vanos, meaning only the intake valve timing is varied. This vanos unit is part of BMW 6-cylinder engines M50TU, M52, US S50, S52.

You can find them in the 3-series E36 (93-97), 5-series E34 (93-95) / E39 (96-98), 7-series E38 (95-98), Z3 Roadster 2.8 E36 (96-98), EU Z3 Coupe 2.8 E36 (96-98), US M3 E36 (94-99), and US Z3 M E36 (98-99).

This vanos has been experiencing a failure.

Diagnostics indicate that the failure results from deterioration of the Vanos piston seal O-ring. The O-ring is made from Buna (Buna-N, NBR, Nitrile), a common material for O-rings. However, Buna has limitations in temperature and chemical resistance.

Unfortunately it is fairing quite badly in the vanos/engine environment. The O-ring has been found to harden, shrink, and have flat surfaces. This deterioration is causing the O-ring to lose its functional characteristics and thus cause the vanos to fail.

BMW has been contacted about this issue but has decided not to take action, stating, “No further development will be done.”

However, new (rebuilt) VANOS units continue to be sold with the same Buna O-ring. It is important to note that BMW does not offer the VANOS piston seal or O-ring as a separate replacement part.

For instance, here is a link to the Roadfly BMW E39 forum where much of this information regarding the double VANOS was first made public: http://bimmer.roadfly.com/bmw/forums/e39/7494631-2.html.

Furthermore, the double VANOS shares the same seal design and O-ring failure as the single VANOS. Specifically, the piston O-ring lies under and provides support to a piston Teflon seal ring. Consequently, replacing the O-ring requires removing the Teflon seal to access the O-ring. However, the Teflon seal is extremely difficult to remove from the piston seal groove without damaging it. Thus replacing the O-ring necessarily requires replacing the Teflon seal.

Single Vanos 6-cyl

The Buna O-ring can be replaced with an O-ring made from Viton. Viton (FKM, Fluorocarbon) has similar functional characteristics to Buna, but has much higher temperature and chemical resistance characteristics. It”s also recommended for the automobile engine environment. The VANOS Teflon (PTFE-filled) seal is not a standard part and requires semi-custom manufacturing.

The single vanos has one piston with one seal/O-ring. Additionally, a VANOS seal/O-ring repair kit is available from Beisan Systems (bee-saan) at www.beisansystems.com/products.

This kit includes a vanos replacement OEM Teflon seal and enhanced (Viton) O-ring. Moreover, here is a link to the Roadfly BMW E39 forum where the double vanos seals product was first introduced: http://bimmer.roadfly.com/bmw/forums/e39/8705552-2.html. It is important to note that the double vanos utilizes the same Teflon and O-ring material and design as the single vanos. Therefore, the repair process for both types of vanos systems is quite similar.

Symptoms

Cars experience:
Overall loss of torque and power, particularly in the lower RPM range, < 3k. Bogging then surging at 3k RPM. Uneven power distribution and RPM transition. Engine hesitations in the lower RPM range, < 3k. Louder idle and intermittent idle RPM hiccups. Difficult takeoffs. Loss of power and bogging when AC on. Increased fuel consumption.
Repairing the vanos seals provides:
Overall increase in torque and power, particularly in the lower RPM range, < 3k. Resolution of bogging then surging at 3k RPM. Smooth even distribution of power and RPM transition. Resolution of engine hesitations in the lower RPM range, < 3k. Quiet stable idle. Smooth easy takeoffs. Improved performance when AC on. Reduced fuel consumption, by ~10%.

In some cases the engine computer will generate the following fault code:
P1519 (BMW 212, 0xD4): Vanos mechanically stuck (jamming).

Diagnosis

A vanos fault code, as described above, without previous tampering with the engine timing, is most likely a vanos seals failure indication.

Otherwise, you must remove the VANOS from the engine for inspection. After removing the VANOS cylinder cover, inspecting how the piston seals fit in the cylinders will reveal a loose fit, indicating seal failure. Removal of the seals from the piston will show the inner O-ring has flat spots and a loss of elasticity.

In general, a diagnosis is not necessary. The vanos Buna O-ring is deteriorating in 20k miles (32k kilometers). Thus essentially all the cars with this vanos have a deteriorated seal O-ring and a failing vanos.

Repair Procedure

The following is an E36, E34 & E39 single vanos piston seals R&R (remove and replace) procedure.

If the valve cover gaskets are over 40k miles (64k kilometers) old, then it”s prudent to replace them during this repair. If they are over 80k miles (128k kilometers) old, then it is a requirement to replace them during this repair, otherwise they might leak due to being dismounted and reused. These gaskets have an estimate lifespan of ~60k miles (96k kilometers) and replacing them during this repair requires no extra effort. The needed parts and replacement procedure are included as optional.

Repair time: 4 hours mechanic, 6+ hours DIY.

Parts, Tools, and Shop Supplies

The first item in the kit is the Single Vanos Seals Kit (6-cyl) (BS011), available for $30 each at www.beisansystems.com . In addition , you will need a vanos gasket (part number 11-36-1-740-840), which costs $7.48 each. Finally , don’t forget to include two vanos oil hose/pipe washers (part number 32-41-1-093-596), priced at just $0.25 each.

Valve Cover Gasket Replacement Parts:
To begin with, the valve cover gasket set is available for different engine types. For instance, the M50TU and US S50 engines (1993-1995, silver metal cover) require part number 11-12-0-034-107, priced at 32.89each.Similarly,theM52andS52engines(1996−1999,blackplasticcover)usepartnumber11−12−0−034−108,whichcosts32.89each.Similarly,theM52andS52engines(1996−1999,blackplasticcover)usepartnumber11−12−0−034−108,whichcosts35.70 each.

In addition to the gasket set, you will need other components. For example, 15 valve cover bolt grommets (11-12-1-437-395) are required, priced at 1.37each.Furthermore,anoilfillneckgasket(11−12−7−526−447)isnecessaryandcosts1.37each.Furthermore,anoilfillneckgasket(11−12−7−526−447)isnecessaryandcosts2.29 each.

Easily Breakable Parts:
When working on the replacement, it’s important to handle certain parts with care because they are prone to breaking. Specifically, you will need 4 cover bolt/nut caps (11-12-1-726-089), priced at 3.05each.Additionally,2fanshroudrivets(17−11−1−712−963)arerequired,costing3.05each.Additionally,2fanshroudrivets(17−11−1−712−963)arerequired,costing0.35 each. For E36 models, 2 air duct rivets (51-48-1-915-964) are needed, priced at 0.49each.Lastly,forE39models,aradiatoroverflowneck(17−11−0−419−132)isnecessaryandcosts0.49each.Lastly,forE39models,aradiatoroverflowneck(17−11−0−419−132)isnecessaryandcosts1.67 each.

Easily Lost Parts:
Finally, don’t overlook small parts that are easily lost during the process. For instance, 4 engine cover pads (11-12-1-730-352) are required, priced at $2.35 each.

E36 & E39: Small adjustable hose clamp. Needed if radiator overflow hose OEM clamp not previously replaced with adjustable clamp.

First , for scraping and prying tasks, you will need a gasket scraper and a putty-knife. Additionally , a straight pick tool, razor knife, and medium nose pliers (small) will come in handy for more precise work.

Next , for general assembly and disassembly, you’ll require several screwdrivers and wrenches. This includes a Philips screwdriver (medium), a Torx driver (any small size), and three flathead screwdrivers (two medium, one small). Moreover , you’ll need a tack lifter, needle file, small mirror, and magnet pickup for detailed work.

Moving on to sockets and wrenches , you’ll need a variety of sizes and types. For 1/2″ tools, include a 22mm socket, 19mm socket, and both a standard and long-arm 1/2″ ratchet. In addition , for 3/8″ tools, gather a 13mm socket, 10mm deep socket, 10mm socket, E-10 Torx socket, a 3/8″ ratchet, and a 3/8″ long-arm ratchet. Finally , for 1/4″ tools, a single 8mm socket and a 1/4″ ratchet will suffice.

For extensions , you’ll need a short 3/8″ socket extension and a short 1/4″ socket extension. Lastly , don’t forget your torque wrench, which should be capable of handling 8 Nm (6 ft-lb) and 50 Nm (37 ft-lb).

First , ensure you have the essential camshaft lock blocks (part number 11-3-240), which are crucial for securing the camshafts during timing procedures. Additionally , a sprocket turner (part number 11-5-490) is necessary for safely rotating the camshaft sprockets.

Next , to lock the crankshaft in place, you’ll need the crankshaft lock pin (part number 11-2-300). Furthermore , for maintaining proper tension on the camshaft, the camshaft tensioner lock pin (part number 11-3-292) is required. Alternatively , if the tensioner lock pin is unavailable, a small set nail (3d) can be used as a substitute.

First , you’ll need a 32mm combo wrench, which is essential for loosening the fan nut. In addition , a BMW water pump pulley holder (part number 11-5-030), priced at $20 each, is required to hold the pulley steady while working on the fan.

Finally , a handheld sledge hammer (3 lb) can be used to gently tap the wrench and break the fan nut free if it’s tightly secured.

First , you’ll need a ~6″ length of 5/16″ (8mm) vacuum hose, which is essential for creating a makeshift tool to help remove or install certain components. Additionally , two small clamps will be required to secure the vacuum hose in place during the process.

To complete this repair, you will need the following materials:

• Paper towels
• Water-based cleaner (such as Simple Green, diluted 1:10)
• Spray lubricant
• Brake cleaner
• Engine oil (synthetic 5W30)
• Parts plate
• RTV sealant
• Large cup

Not shown: A large pad (quilt), an oil pan, and three small cloth towels.

Repair Preparation

Before starting the repair, ensure the car engine is completely cold to avoid burns or other risks.

For M50TU and M52 engines, specific details will be labeled accordingly:

• M50TU (1993–1995): Features a silver metal valve cover.
• M52 (1996–1999): Features a black plastic valve cover.

Additionally, all right and left references in this guide assume you are standing at the front of the car, facing the engine bay.

Component Removal

Fan & Shroud Removal

• E36: Steps for removing the fan and shroud.
• E34: Steps for removing the fan and shroud.
• E39: Steps for removing the fan and shroud.

Cabin Filter Housing Removal

• E39: Steps for removing the cabin filter housing.

Valve Cover Removal

Instructions for removing the valve cover follow

Removing the Engine Top Covers

Unscrew the oil fill cap, remove the left engine cover, and then reinstall the oil fill cap.

First , begin by removing the engine top covers. To do this , pry off the two center caps on each engine cover using a flathead screwdriver.

Next , move on to the fasteners securing the covers. On the right cover , unscrew the two bolts, and on the left cover , remove the two nuts. For this step , use a 10mm socket (3/8″) with a ratchet and extension to ensure proper leverage and ease of removal.

Use a magnet pickup tool if necessary.

Remove the right engine cover.

First , locate the valve cover vent hose at the right front corner of the cover. Once located , remove the hose by prying up the retaining clip using a flathead screwdriver.

Next , with the clip released, pull off the connector carefully to avoid damaging any surrounding components.

M52 Engine:
To start, remove the valve cover vent hose located at the right front corner of the cover. Next, press in the hose connector ring clip on both sides and gently wiggle the connector off. Warning: Avoid pulling the connector off directly, as this can cause a sudden release and potentially break the hose. Instead, carefully wiggle the connector to remove it safely.

Afterward, disconnect the ignition coil’s electrical harness. For each coil, begin by pulling up on the coil connector’s metal lock. Then, pull off the cable’s electrical connector.

M50TU Engine:
In contrast, for the M50TU engine, you will need to remove the connector cables from the valve cover cable bracket, which is located on the left side of the cover.

Now , returning to the M52 engine, the next step is to remove the coil harness ground wire. Specifically , this wire is attached to the valve cover bolt/stud located between coils 2 and 3.

To accomplish this , use an 8mm socket with a 1/4″ ratchet and extension to carefully unscrew the bolt. Additionally , keep a magnet pickup handy for convenience, as it can help retrieve the bolt or wire if they slip out of reach.

First , begin by disconnecting the coil harness rail from the valve cover clips. To accomplish this , gently pry on each valve cover coil harness rail’s right-side clip using a flathead screwdriver.

Once the clips are released , carefully pull out the coil harness rail. Afterward , once the rail is fully removed, pull off the complete coil harness and set it aside on the left side of the engine bay. Be sure to position it securely so that it doesn’t interfere with other components during the rest of the procedure.

Next, proceed to remove the coils. Note: The mounting method differs between engine types. For the M50TU engine, the coils are mounted with nuts, whereas for the M52 engine, the coils are mounted with bolts. Use a 10mm socket with a 3/8″ ratchet and extension to remove the 2 mounts at each coil.

M50TU-Specific Step:
If you’re working on the M50TU engine, make sure to maintain the coil harness cables in the brackets mounted with coils 3, 4, and 5. This will help keep the harness organized and prevent tangling during reinstallation.

Finally, pull up and out all the coils from their positions. Important Note: Be sure to maintain the coil/cylinder association during removal to ensure proper reinstallation later. This is not necessary, but is good practice.

First , remove the coil ground strap(s) using an 8mm socket with a 1/4″ ratchet and extension.

For the M50TU engine , locate and remove the ground strap at cylinder 6. This step is straightforward , as there is only one ground strap to detach in this model.

On the other hand , for the M52 engine, you’ll need to remove ground straps at both cylinders 1 and 6. Start with one cylinder , then proceed to the next, ensuring all connections are fully detached before moving on.

Begin by removing the 11 valve cover mounting bolts, along with their washers and grommets, located around the perimeter of the valve cover. For this task , use a 10mm socket with a 3/8″ ratchet and extension. If necessary , a flathead screwdriver can assist in prying or accessing difficult areas.

As you work , take care to methodically remove each bolt to avoid missing any. Importantly , don’t forget the bolt hidden in the left rear corner—a common spot that’s easy to overlook.

After removing all bolts, double-check the perimeter to ensure none remain before proceeding to the next step.

First , focus on the valve cover mounting bolts located at the center of the valve cover.Specifically, you need to remove four bolts or studs along with their washers and grommets.

As you proceed , note that the third bolt/stud from the front is identical to the perimeter bolts in terms of size and removal method. To remove these bolts , use a 10mm socket (3/8″) with a ratchet and extension for optimal leverage.

Then, double-check that you haven’t left any components behind before moving on to the next step. Use a flathead screwdriver if needed. A flathead screwdriver may help if needed.

M50TU Engine: The second bolt/stud from the front is the same as the perimeter bolts.

Remove valve cover from engine head.
Insert blade (putty-knife) between valve cover gasket and engine head at all front end accessible locations to break gasket bond.
Pull up and remove valve cover. If resistant, insert blade (putty-knife) between valve cover gasket and engine head at sticking locations.
Note: If the valve cover cannot be removed, double-check that all 11 perimeter bolts and 4 center bolts/studs have been taken out. If the valve cover is stuck, pull up on the free front end to break the gasket bond on the remaining section.

M50TU: Pull up coil harness cables to allow access for cover removal.
M52: Remove cables from valve cover rear bracket/slot. Lift up on rear cables to allow access for cover removal.

Maintain cover perimeter gasket with cover.
Valve cover perimeter gasket will stick at rear half moon dips due to RTV sealant. Pull up on gasket to release.
Remove valve cover sparkplug well gaskets.

Note: If gasket is stuck to engine head, attempt inserting blade between gasket and head from an edge (putty-knife). This facilitates gasket removal without breaking plasticized brittle gaskets into pieces.

First , begin by removing the intake camshaft cover. To do this , gently pull up on the cover to release the clips that secure it in place. Once the clips are released , carefully lift the cover off and remove it from the engine bay.

Next , with the camshaft cover removed, it’s important to lock the engine timing to prevent any movement during subsequent steps. This ensures that the engine remains properly aligned and avoids potential damage.

If manual transmission, place transmission in neutral. This allows turning of crankshaft.
Turn crankshaft pulley clockwise until cylinder 1 intake and exhaust cams point to each other at ~45 degree angle (22mm socket 1/2″ / 1/2″ long-arm ratchet).
Note: Turning crankshaft counter clockwise is acceptable.

First , adjust the crankshaft pulley to properly position the exhaust camshaft. For this step , use a 22mm socket with a 1/2″ drive and a 1/2″ long-arm ratchet for better leverage.

Next , carefully rotate the crankshaft pulley until the rear camshaft square is perfectly flush with the head surface. This alignment is crucial , as it ensures the camshaft is correctly positioned for subsequent steps.

Once the adjustment is complete , double-check that the camshaft square is flush with the head surface before proceeding further.

First , ensure both sides of the rear wheels are securely chocked for safety. This is an essential step to prevent the car from moving while you work.

Next , inspect the TDC (Top Dead Center) timing marks on the engine timing cover and crankshaft harmonic balancer. These marks are critical for proper engine timing and are located at approximately the 11 o’clock position. For better visibility , use a mirror to get a clear view of the marks.

Once you’ve located the marks , adjust the crankshaft pulley to align the TDC timing marks. To do this , use a 22mm socket (1/2″) with a long-arm ratchet for precise control.

Note that the viewing angle can affect alignment. To ensure accuracy , slightly tilt your view toward the 11 o’clock position when checking the marks. This small adjustment helps confirm that the alignment is correct before proceeding further.

Raise the front of the car and secure it on jack stands following the appropriate procedure.

First , locate the crankshaft lock hole plug at the engine’s right rear side (using the front orientation as your reference point). This plug is typically small and may be easily overlooked , so take your time to identify its position.

Next , to remove the plug, insert a narrow driver—such as a torx bit driver—into the plug’s eyelet. Once inserted , gently pry the plug out by leveraging the driver against the engine frame. Be careful during this step , as excessive force could damage the surrounding area.

After the plug is removed , set it aside in a safe place to avoid losing it, and proceed with the next steps in your task.

First , insert a narrow driver into the crankshaft lock hole to roughly measure its depth. This step is important because it provides a reference for the correct insertion of the crankshaft lock pin in the next step.

Once the driver is inserted , take note of the approximate depth of the hole. This measurement will ensure that the crankshaft lock pin is inserted to the appropriate depth without causing any damage or misalignment.

After recording the measurement , you’ll be ready to proceed with the next step, which involves inserting the crankshaft lock pin.

Insert crankshaft lock pin into crankshaft lock hole.
Pin should insert as far as narrow driver in previous step.

When lock pin is fully inserted crankshaft pulley will be locked in place and can not be rotated. Check crankshaft pulley is locked (22mm socket 1/2″ / 1/2″ long-arm ratchet).
Note: Crankshaft pulley will have very slight play (movement) when locked.

If the retention pin does not fully insert or the crankshaft pulley does not lock, adjust the crankshaft pulley in slight increments and attempt pin insertion (using a 22mm socket, 1/2″ drive, and 1/2″ long-arm ratchet). Should the securing pin still resist full insertion, clean the lock hole surfaces with a needle file. Persistent difficulty inserting the locking pin may indicate rust and grime at the engine case hole and/or the drive plate/flywheel hole.

Insert wide diameter driver into crankshaft lock hole instead of lock pin (Philips).
Precisely align timing marks on engine timing cover and crankshaft harmonic balancer.

Lower car from jack stands (follow appropriate procedure).

Removing Rear Valve Cover Studs and Excess Sealant

Clean excess RTV sealant from the top of the engine head, especially at the half-moon corners, to ensure a proper seal when reinstalling the valve cover.

Remove the three valve cover studs at the rear of the engine head using a 10mm socket (3/8″) with a 3/8″ long-arm ratchet & extension.

Note for E36: There is no room for a socket extension, so use a direct socket connection.

Place exhaust camshaft lock block (bolt hole on block right) on exhaust camshaft rear square and engine head.
Note: Lock block might not fit well until camshaft position adjustment in next step.

Place open wrench (24mm combo wrench) on exhaust camshaft hex at middle of camshaft.
Adjust camshaft to allow flush seating of camshaft lock block on engine head (24mm combo wrench).
For final fine tuning, rock wrench back and forth while feeling block by hand.

Place intake camshaft lock block (bolt hole on block left) on intake camshaft rear square and engine head.
Note: Lock block might not fit well until camshaft position adjustment in next step.

Adjusting the Camshaft for Lock Block Placement

Adjust the camshaft as needed to allow the camshaft lock block to seat flush on the engine head
For final fine tuning, rock wrench back and forth while feeling block by hand.

Position a 24mm combo wrench on the intake camshaft hex at the middle of the camshaft.

Install lock blocks bracket and bolts (13mm socket 3/8″ / 3/8″ ratchet).
Note: Bracket helps maintain lock blocks position and counters block movements.

Removal of vanos

Remove vanos oil hose and bolt (19mm combo wrench).
Note: There are 2 washers, one at each side of hose end contact surfaces.
Discard washers.

Detach engine lift bracket at vanos intake solenoid.
Clear top and bottom bolts (13mm socket 3/8″ / 3/8″ ratchet & extension).
Eliminate bracket.

Disconnecting the Vanos Intake Solenoid Electrical Connector

Press the spring clip on the connector and pull off the cable connector to detach it.

Disconnect the electrical cable connector from the Vanos intake solenoid.

Move the valve cover vent hose and Vanos oil hose to the right side of the oil filter canister to create more working space.

Follow the solenoid cable by pulling it upward to locate the electrical connector.

M50TU:
Remove cable bracket E-clips under vanos.
Pull off E-clips to left side (medium nose pliers).

M50TU:
Remove cable bracket from mounting studs.
Pry off electrical cable from back of cable bracket and remove bracket.

M52:
Remove vacuum pipe 2 bracket mounting nuts (10mm standard & deep socket 3/8″ / 3/8″ ratchet).

M52:
Pull off vacuum pipe from mounting studs.
Pull vacuum pipe further out and lay down on thermostat and radiator lower hose.
Note: Side vacuum hoses provide slack needed to pull forward on vacuum pipe.

Remove 2 vanos exhaust sprocket access bolts (19mm socket 1/2″ / 1/2″ long-arm ratchet).

Insert cloth towel below exhaust sprocket. This will prevent any falling bolt from dropping into oil sump.

Detach 4 exhaust sprocket mounting bolts (E-10 torx socket 3/8″ / 3/8″ ratchet & extension).
Take off any dropped bolt with magnet pickup and not by hand.

Clear cloth towel.

Install camshaft chain tensioner lock pin.
Press down on tensioner and insert pin up to chain.
Note: Lock pin should not be inserted under chain as it can inadvertently tension chain.

Remove vanos 6 mounting nuts at front lower half of vanos (10mm standard & deep socket 3/8″ / 3/8″ ratchet & extension).
M52: 2nd nut from left and 1st nut from right were removed previously when removing vacuum pipe.

Cover AC belt and lower radiator hose to protect from oil leakage (towels).
Install small bag over vanos oil feed hole to catch leaking oil (vanos seals product bag).

Remove vanos from engine head.
Mount sprocket turning tool on exhaust sprocket.
Wiggle vanos forward off engine head while simultaneously turning exhaust sprocket clockwise.
Vanos Removal and Oil Drainage

• Note: Turning the exhaust sprocket clockwise creates chain slack, allowing the intake sprocket to rotate clockwise, which in turn enables the Vanos splined shaft to retract.
• Caution: A significant amount of oil will drain from the Vanos oil feed hole.

Draining the Vanos Unit:

1. Move the Vanos unit to an oil receptacle (such as an oil pan).
2. Tilt the Vanos unit to help drain oil from both the inner oil relief spout and the outer oil feed hole.

Vanos Gasket Removal:

3. Lay the Vanos unit flat on a table with the inner side facing up.
4. Remove and discard the old Vanos gasket from the engine head.

Next Step: Replacing the Vanos Piston Seals

During following seals installation procedure, great care should be taken to not drop and damage vanos components. Perform work over table, so if part is dropped it will fall to table top.

Remove vanos cylinder cover mounting bolts (10mm socket 3/8″ / 3/8″ ratchet).

Vanos Cylinder Cover and Piston Removal

1. Remove the cylinder cover along with the splined shaft and piston from the Vanos body.
2. Drain oil from the cylinder and cover into an oil receptacle (oil pan).
3. Wipe off excess oil from all Vanos components using clean towels.

Failure Diagnosis Verification

Inspect the Vanos cylinder wall by touch. It should feel exceptionally smooth with no noticeable irregularities or marring.
Note: Seal sliding wear patterns will be present. Also cylinder wall will not be as polished at ends of cylinder.

Insert and move the piston in and out of the Vanos cylinder to check for a loose fit.

Piston seals removal and installation

Cut cross section of piston Teflon seal in piston groove (razor knife).
Note: Rocking of blade while pressing helps create cutting motion.

Remove cut Teflon seal from piston grove.

Cut cross section of piston O-ring in piston groove (razor knife).
Note: Rocking of blade while pressing helps create cutting motion.

Remove cut O-ring from piston grove.

Note: Deteriorated O-ring will be flattened at top and bottom surfaces, shrunk in size, and plasticized thus having a loss of elasticity. This is the common vanos failure mode.

After both piston seal rings are removed, piston groove will be metal.
Wipe clean piston groove (towel).

Install new O-ring (circular brown) in piston groove.
Insert O-ring in piston groove at one end, and stretch other end over piston and drop into groove (hands/fingers).
Note: O-ring should not be twisted during installation process.

Verify O-ring is not twisted in piston groove. Adjust and center as necessary (pick tool).

If Teflon seal in cold environment, <65F (18C), soak seal in warm water for 2+ minutes.
Remove and dry Teflon seal just before installation.

Note: Perform following step on ground over large pad while kneeling with knees on pad. This minimizes risk of dropping piston and damaging its surfaces.

Teflon Seal Installation and Resizing

1. Install the new Teflon seal (rectangular black) into the piston groove.
   • Insert one end of the seal into the groove.
   • Gently stretch the other end over the piston and drop it into place using your hands/fingers.
   • Avoid excessive stretching.

Important Notes:

• Stretch the Teflon seal evenly to prevent scuffing or damage.
• Some sliding of the seal over the piston rim is normal.
• Moderate force is required to stretch the seal.

Once installed, the Teflon seal will fit loosely in the piston groove.

Piston Teflon Seal Resizing

Coat the Teflon seal and adjacent piston surfaces with assembly lubricant to facilitate proper resizing and installation.

Apply assembly lubricant (engine oil) to the Vanos cylinder wall, ensuring full coverage, including the chamfer (rim bevel).

Press in on helical gear shaft to fully separate piston from cylinder cover.
Insert piston into cylinder at ~30 degree angle, then rotate piston to insert into cylinder.
Rotate piston to be flush with cylinder. As piston is rotated, excess seal protruding from piston groove will be collected and pressed into piston groove.
If seal is binding, reposition piston and attempt again. With each attempt seal will partially resized. Eventually piston can be fully rotated without binding seal.

Press in on splined shaft to fully insert and properly position piston in cylinder.
Verify cylinder cover is fully seated on vanos body.

Allow piston to sit in cylinder for 2 minutes then remove. Teflon seal will be compressed close to original size.

Reinstall piston in cylinder.
Press in on splined shaft to fully insert and properly position piston in cylinder.
Rotate cylinder cover to achieve proper mounting holes orientation.
Mount cover 5 bolts (10mm socket 3/8″ / 3/8″ ratchet).
Fully tighten, 10 Nm (7 ft-lb) (10mm socket 3/8″ / 3/8″ torque wrench).
Note: Tighten bolts evenly in crisscross pattern.

Double check piston movement in vanos cylinder by inserting and retracting helical gear shaft. This will take force due to new seal tight fit.

Comparison of new seal piston resistance to movement in cylinder to old seal piston movement in cylinder verifies old seal failure.

Fully insert vanos splined shaft in vanos.

Cleaning of parts

Note: When cleaning parts, spray cleaning compound on towel then wipe component with towel. Components can also be placed in a small container and sprayed with cleaning compound then individually wiped with towel.

Clean all mounting bolts/studs, nuts, washers, rubber grommets, ground strap ends (brake cleaner & towels)

Clean vanos matting surfaces; head, valve cover, oil feed (brake cleaner & towels).

Remove sealant compound on engine head (gasket scraper, finger nail).
Clean engine head matting surfaces; vanos, vanos studs, valve cover gaskets (brake cleaner & towels).

Clean coils mounting contact surfaces (at coils) (brake cleaner & towels).

Remove sealant on valve cover gasket (pick tool, finger nail).
Clean valve cover gaskets (water based cleaner & towels).
Clean valve cover mating surfaces; gaskets and mounting bolt access holes (water based cleaner & towels), coils (brake cleaner & towels).

Optional: Replacement of valve cover gaskets

Replace valve cover gaskets.
Eradicate 15 valve cover bolt grommets from bolts and install new grommets on bolts.
Cut valve cover oil fill cap. Remove oil fill neck gasket and install new gasket. Mount valve cover oil fill cap.

Note: If old gasket is stuck to valve cover, attempt inserting blade between gasket and cover starting from an edge (putty-knife). This facilitates gasket removal without breaking plasticized brittle gaskets into pieces.

Installation of vanos

Note: Verify old vanos gasket is removed from engine head and surface clean.
Mount new vanos gasket onto engine head front. Mount top corners onto dowels and place gasket flush with head surface.
Note: Gasket is asymmetric.

Mount sprocket turning tool onto exhaust sprocket.
Rotate exhaust sprocket clockwise as far as possible. This will rotate intake sprocket clockwise as far as possible.
Note: This step is critical for proper installation of vanos in next step.

Fully insert vanos splined shaft in vanos. Note: This step is critical for proper installation of vanos.
Mount vanos onto engine head front.
Insert vanos onto engine head studs. Insert helical gear shaft into intake sprocket.
Rotate helical gear shaft and slightly insert into sprocket. Helical gear shaft will slightly insert into sprocket and stop rotating.

Important Note: It turned out that the best method for the largest possible adjustment travel is to look for the first matching pair of teeth with which the helical gear shaft already slides in without using the lever to turn the exhaust gear counterclockwise!
When you have found the smart pair of teeth, simply press the Vanos with the ball of your hand onto the cylinder haed and screw the housing tight. No longer turn the lever counterclockwise on the outlet gear, otherwise you pull the piston out of the Vanos and the timing will be wrong!
This video shows how to find the smart tooth: Finding the smart teeth
With this method you can skip the next step:

Mount sprocket turning tool onto exhaust sprocket.
Rotate exhaust sprocket counter clockwise while pushing in on vanos to insert helical spline shaft into intake sprocket. Wiggle vanos and sprocket tool to help insertion.
Note: It is critical to insert into first possible gear spline alignment. Push vanos in while turning sprocket.
Insert vanos onto engine head studs, then vanos top corners onto head matting dowels.

M52: Do not install 2nd nut from left and 1st nut from right in this step. Thus only 4 nuts will be installed.
M50TU: Install all 6 nuts.
Install vanos mounting nuts and tighten evenly working back and forth (10mm standard & deep socket 3/8″ / 3/8″ ratchet & extension).
Fully tighten, 8 Nm (6 ft-lb) (10mm standard & deep socket 3/8″ / 3/8″ torque wrench & extension).

Remove camshaft chain tensioner lock pin.
Press down on chain tensioner and remove lock pin.

Insert cloth towel below exhaust sprocket. This will prevent any falling bolt from dropping into oil sump.

Install 4 exhaust sprocket mounting bolts and tighten evenly in crisscross pattern (E-10 torx socket 3/8″ / 3/8″ ratchet & extension).
Extract any dropped bolt with magnet pickup and not by hand.
Fully tighten, 20 Nm (15 ft-lb) (E-10 torx socket 3/8″ / 3/8″ torque wrench & extension).

Cut cloth towel.

Install 2 vanos exhaust sprocket access bolts (19mm socket 1/2″ / 1/2″ ratchet).
Fully tighten, 50 Nm (37 ft-lb) (19mm socket 1/2″ / 3/8″ torque wrench & 3/8″ to 1/2″ socket adapter).

M50TU:
Install cable bracket under vanos onto electrical cable.
Press cable into bracket rear cable slot.

M50TU:
Install cable bracket onto mounting studs.
Install cable bracket E-clips onto mounting studs (medium nose pliers).

M52:
Install vacuum pipe onto mounting studs.
Install 2 bracket mounting nuts (10mm standard & deep socket 3/8″ / 3/8″ ratchet).
Fully tighten, 8 Nm (6 ft-lb) (10mm standard & deep socket 3/8″ / 3/8″ torque wrench).
Verify 6 vanos mounting nuts fully tightened, 8 Nm (6 ft-lb) (10mm standard & deep socket 3/8″ / 3/8″ torque wrench).

Install vanos intake solenoid electrical cable connector.
Press in connectors until clip snaps in place.

Install engine lift bracket at vanos intake solenoid.
Install long bolt at top and short bolt at bottom (13mm socket 3/8″ / 3/8″ ratchet & extension).
M50TU: Install ground wire with top bolt.
Fully tighten, 8 Nm (6 Ft-lb) (13mm socket 3/8″ / 3/8″ torque wrench & extension).

Install vanos oil hose with bolt and 2 new washers (19mm combo wrench).
Mount first washer on bolt. Insert bolt through hose. Mount second washer on bolt. Screw bolt onto vanos.
Fully tighten, 32 Nm (24 ft-lb) (19mm combo wrench / by feel).
Note: Insert rod (flathead) between hose pipe and vanos intake solenoid to keep hose from turning.

Unlocking engine timing

Remove camshaft locking blocks.

Remove sealant compound on engine head half moon corners (gasket scraper, finger nail).
Clean engine head matting surface (brake cleaner & towels).

Install 3 valve cover studs at rear of engine head (10mm socket 3/8″ / 3/8″ ratchet & extension).
Fully tighten, 8 Nm (6 Ft-lb) (10mm socket 3/8″ / 3/8″ torque wrench & extension).
E36: No room for socket extension.

Raise front of car and place on jack stands (follow appropriate procedure; chock both sides of both rear wheels).

Remove crankshaft lock pin from crankshaft lock hole.
Note: Wiggle pin while pulling to help release.

Insert plug into crankshaft lock hole.
Note: If plug difficult to insert, insert narrow driver into plug eyelet and press in plug (torx bit driver).

Lower car from jack stands (follow appropriate procedure).

Installation of valve cover

Install intake camshaft cover.
Orient cover with arched end at rear and open end at front.
M50TU: Lift coil electrical harness wires to facilitate access.
Press down on cover to lock tabs on valvetrain.
When fully installed, cover will have no vertical movement and slight axial (fore/aft) play.

M52:
Install valve cover perimeter gasket and sparkplug well gaskets on valve cover.

M50TU: Install Valve Cover Spark Plug Well Gaskets

First , begin by installing the valve cover spark plug well gaskets onto the engine head. This step is essential to ensure a proper seal around the spark plug wells and prevent oil leaks.

Next , carefully orient the gaskets to fit around the valve cover studs. Pay close attention to the orientation, as the gasket cup side should face downward. This positioning is crucial to ensure the gaskets sit correctly and provide an effective seal.

Once the gaskets are in place , double-check their alignment with the valve cover studs and confirm that the cup side is facing down. This final check will help avoid any issues when reinstalling the valve cover.

Place thin coat of RTV sealant at 2 engine vanos/head contact points and head rear half moon corners.
Allow sealant to solidify for 2 minutes before mounting valve cover.

M50TU:
Install valve cover perimeter gasket onto engine head/vanos. Take care to align properly before placement.
Lift coil electrical harness wires to facilitate access.

Install valve cover onto engine head/vanos. Take care to align properly before placement.
M50TU: Lift up coil electrical harness wires to facilitate access.
M52: Lift up rear cables for access. Install rear cables in cover rear bracket/slot.

Install Valve Cover Bolts

First , begin by installing the 11 bolts with their washers and grommets around the perimeter of the valve cover. For this step , use a 10mm socket (3/8″) with a 3/8″ ratchet and extension to ensure proper tightening.

Next , install the 4 bolts or studs with their washers and grommets at the center of the valve cover. This step is crucial to secure the cover evenly and prevent leaks.

For the M50TU Engine:

Note that the second bolt/stud from the front in the center row is the same size and type as the perimeter bolts. This ensures consistency across the installation process.

For the M52 Engine:

In contrast , for the M52 engine, the third bolt/stud from the front in the center row matches the perimeter bolts. Be sure to identify this bolt correctly to avoid confusion during installation.

Once all bolts are installed , double-check that each one is securely tightened and that all washers and grommets are properly seated. This final verification will help ensure a leak-free seal.

Tighten bolts/studs evenly working back and forth, assuring even pressure distribution on cover. Tighten until bolts/studs bottom out on head.
Fully tighten, 10Nm (7 ft-lb) (10mm socket 3/8″ / 3/8″ torque wrench & extension).

Install Coil Ground Strap(s)

First , install the coil ground strap(s) using an 8mm socket (1/4″) with a 1/4″ ratchet and extension to secure the mounting nut(s).

For the M50TU Engine:

Begin by attaching the ground strap at cylinder 6. This step ensures proper grounding for the ignition system.

For the M52 Engine:

In contrast , for the M52 engine, install ground straps at both cylinders 1 and 6. Start with one cylinder , then proceed to the next to ensure all connections are secure.

Note that the highly bent end of the ground strap mounts on the valve cover stud. Specifically , the cylinder 1 strap connector should be oriented toward the top corner, while the cylinder 6 strap connector should face the bottom corner. This orientation is important as it facilitates the alignment of the strap’s loose ends with the coil mounts, ensuring a proper and secure connection.

Install coils.
M50TU: Coils mount with nuts.
M52: Coils mount with bolts.
Install each coil into original sparkplug well with 2 mounts (10mm socket 3/8″ / 3/8″ ratchet & extension).
Note: Coil boot will not fully insert onto sparkplug during initial mount. This is normal.
M50TU: Mount coil harness cable brackets with coils 3, 4, 5. Mount ground strap with coil 6.
M52: Mount ground straps with coils 1 & 6.
Rotate between coil mounts to mount coil evenly.
M50TU: “Mount coils 3, 4, 5 evenly together to assure even mounting of coil harness cable brackets.
Fully tighten, 10Nm (7 ft-lb) (10mm socket 3/8″ / 3/8″ torque wrench & extension).

Install Ignition Coil Electrical Harness

First , begin by installing the ignition coil electrical harness according to the specific engine type.

For the M52 Engine:

Start by installing the coil harness rail onto the valve cover and clip it into place. This step ensures that the harness is securely positioned before connecting the coils.

Next , for each coil, lift up on the connector’s metal lock, press in the cable electrical connector, and then push down on the metal lock to secure the connection. Repeat this process for all coils to ensure proper electrical contact.

Afterward , install the coil harness ground wire by attaching it to the valve cover bolt/stud located between coils 2 and 3. For this step , use an 8mm socket (1/4″) with a 1/4″ ratchet and extension to tighten the bolt securely.

For the M50TU Engine:

In contrast , for the M50TU engine, install the coil harness cables into the valve cover’s left-side cable bracket. This step organizes the cables and prevents them from interfering with other components.

Install valve cover vent hose at cover front right corner. Push hose connector onto cover neck until it snaps on.

Engine Cover Installation

Insert the clip at an angle, then gently press down on the opposite end until it clicks into place.

Install the Right-Side Engine Cover

First , align the arches of the right-side engine cover with the intake manifold air tubes on the right side of the engine. This alignment is crucial to ensure the cover fits securely and properly.

Next , secure the cover by tightening the two mounting bolts. For this step , use a 10mm socket (3/8″), a 3/8″ ratchet with an extension, and a magnet pickup tool to retrieve any dropped bolts if necessary.

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Install the Left-Side Engine Cover

Now , move to the left-side engine cover. Before positioning the cover , unscrew the oil fill cap to allow for proper installation.

Once the oil fill cap is removed , position the left-side engine cover in place. Afterward , reinstall the oil fill cap to secure it in its original position.

Finally , secure the left-side cover by tightening the two mounting nuts. As with the right-side cover , use a 10mm socket (3/8″), a 3/8″ ratchet with an extension, and a magnet pickup tool to ensure all components are properly fastened.

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Attach the Bolt/Nut Cover Caps

To complete the process , clip on the two center caps—one for each engine cover. When attaching the caps , align the silver lines on the caps with the edges of the covers. This alignment ensures a clean and professional appearance.

Post repair procedures

Allow RTV sealant to dry a minimum of one hour before driving car.

On first engine start after repair engine will experience a couple engine hiccups at idle. This might be related to trapped air in the vanos.

Check and replenish engine oil.
Drive car, then park car and let engine oil settle.
Remove oil dipstick; wipe dipstick end; fully reinsert dipstick; remove dipstick again; read oil marking. If oil is low add needed (small) amount of new oil at oil fill cap at valve cover.

E36 & E39:
Check and replenish coolant fluid.
When car is fully cold (morning), inspect coolant level at side of expansion tank (reservoir). Coolant should be at mid level. Fill coolant as needed.
Drive car until warm. Slightly open bleed screw at expansion and allow air to escape (Philips). Close bleed screw when only fluid is escaping.
Repeat fill and bleed procedure as needed to achieve proper coolant level.

~100 miles (160 kilometers) of city driving is needed to break-in new seals to achieve smoother RPM transition.

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