BMW DIY – Double VANOS Repair (Rebuild) on M52TU, M54 and M56 6-Cylinder
This DIY can be used as full step-by-step instructions for installation of the BavAuto Double VANOS Seal Repair Kit. Use this DIY in conjunction with the BavAuto DIY video for replacing valve cover gaskets on 6-cylinder 24-valve engines (M50, M52, M52TU, M54, M56, S50, S52, S54).
Fan clutch removal pulley holder tool
This specific VANOS repair kit is applicable to all M52TU, M54 and M56 BMW 6-cylinder engines. These engines are used in the following models:
E46 3-series 99-05 sedans, coupes, convertibles and wagons (except 99 coupes and convertibles): 323i. 323ci, 325i, 325ci, 325cic, 325xi, 325xit, 328i, 328ci, 330i, 330ci, 330cic, 330xi.
E39 5-series 97-03 sedans and wagons: 525i, 525it, 528i (with M52TU), 528it (with M52TU), 530i.
E60 & E61 5-series 04-05 sedans and wagons (only models with the M54 engine): 525i, 525xi, 530i, 530xi.
E36/7 & E36/8, Z3 roadsters and coupes 99-02 (with M52TU or M54 engine): 2.3i, 2.5i, 2.8i, 3.0i.
E85 & E86, Z4 roadsters and coupes 03-08 (M54 engines only): 2.5i, 3.0i.
E83 X3 04-06 (M54 engines only): 2.5i, 3.0i.
E53 X5 00-06: 3.0i.
NOTE – In order to remove the VANOS unit for rebuilding, the valve cover must be removed. Be sure to order the valve cover gaskets and the Reinzosil gasket sealant for resealing the valve cover, along with the VANOS repair kit. See the valve cover removal procedures in the DIY blog post/video below.
1) Remove valve cover (see DIY video).
2) Remove the engine fan and shroud. Specific fan shroud removal steps will vary from model to model. The X5 is shown here. See the applicable Bentley repair manual for specific models.
- Release the two plastic push rivets by pulling the center pins out and then pulling the rivets out.
- Remove the harness plug from the AUC sensor and pull the auxiliary fan harness plug from the mounting clips.
- Use the special 32mm fan clutch wrench and pulley holder tools to remove the fan from the water pump pulley flange. Position the holder over one of the pulley bolt heads and inset the wrench onto the fan clutch nut. Note that the nut is left-hand thread (the wrench will turn clockwise when viewed from the front of the vehicle). Hit the wrench with a hammer to shock the nut loose. Spin the fan off by hand.
- Pull the fan and shroud up and out.
3) Unplug the various electrical connector plugs from the VANOS solenoids, exhaust camshaft sensor and the thermostat (four in all). There are two connector plugs on the lower passenger side of the VANOS housing (cam sensor and VANOS solenoid), one connector on the rear end of the intake VANOS solenoid and the thermostat electrical connector, just under the driver side of the VANOS housing, at the front.
4) Remove the VANOS oil pressure line from the VANOS solenoid valve housing. This is a banjo type fitting. Remove the bolt and watch for the two sealing washers on either side of the banjo hose end. Use an oil absorbing “Pig Mat” towel to catch any oil drainage.
5) Remove the VANOS piston plug caps. Use a 8mm Allen bit to remove the caps. Additional oil will drain from the housing when the caps are removed. Be prepared with a small container to catch the oil.
11) Place the VANOS assembly on the workbench. Using a couple layers of the Pig Mat absorbent mats will help to control the additional oil that will continue to drain from the unit.
12) Remove the 5 bolts securing the intake side VANOS piston cover to the housing and gently pull the cover up and remove it from the housing. The housing will be filled with oil. Hold the piston in place and drain the oil into a container. Once drained, pull the piston out of the housing.
13) Remove the 4 bolts securing the exhaust side VANOS piston cover to the housing and gently pull the cover and piston up and remove it from the housing. Note that there is a moderately strong spring under piston and the piston will be pushed up with the cover. Loosen the bolts in a crisscross pattern, while pushing down on the cover to prevent the cover, piston and spring from flying off. Once the bolts are removed, gently allow the spring to push the piston and cover up and remove them. The housing will be filled with oil. Drain the oil into a container.
14) Clean the VANOS housing, pistons and covers with brake parts cleaner or other solvent based cleaners. If the gasket between the VANOS unit and the cylinder head is attached to the VANOS housing, remove it now and clean the mating surface on the housing.
15) Note that there are eight new seals in the repair kit; four large and four small. Of these, two large and two small seals are black and noticeably stiffer (and have a square cross-section) and the other four are brown and more pliable (and have a round cross-section). The main seals are the black ones and the pressure/expander rings are the brown ones.
17) Remove the piston seals from the pistons.
- Use a miniature pick tool to hook the seal and pull it out of the groove. Be careful not to lever the hook against the edge of the piston as this may mar the piston.
- Pull the seal up until you can pull it out of the groove and off the piston … or the seal breaks.
- Remove the secondary seal pressure ring in a similar manner as used for the main sealing ring. Note that there are two rings in each groove; the main seal and the pressure/expander ring. Be sure to remove both rings.
- Repeat for both the large and the small ends of each piston.
20) Install the brown pressure/expander rings into the piston grooves (large diameter and small diameter rings, for both pistons). Try not to roll the rings into the grooves. Gently stretch them over the pistons and drop them into the grooves. This will prevent them from being twisted in the grooves.
21) Install the black large main seal ring (that has been softening in the hot water) into the piston groove. You must gently stretch the seal over the piston lip and drop it into the groove. These seals absolutely cannot be twisted or rolled.
22) Re-form the main seal ring by inserting the piston into the bore in the VANOS housing. Apply clean oil to the bore and the piston. Gently push the piston into the bore, on an angle. When the last edge is ready to go into the bore, use your finger or a small flat-blade screwdriver to carefully push the seal into the piston groove and then down into the bore. DO NOT PINCH THE SEAL BETWEEN THE PISTON AND THE BORE.
23) Repeat steps 21 and 22 for the second piston.
24) Leave the pistons in the bores for a few minutes.
29) If the old gasket is still affixed to the front of the cylinder head, remove it now.
32) Position the VANOS assembly into place at the front of the cylinder head. Gently push the VANOS assembly to the cylinder head until it is fully seated. If the VANOS housing will not fully mate to the cyinder head, verify proper alignment and that there is nothing being pinched and use a hammer to gently tap the housing until fully seated against the head and gasket.
33) Install the VANOS assembly securing bolts (6 screws and 1 stud) and torque to 6-ftlbs in an outward alternating pattern, starting in the middle.
34) Install the VANOS piston bolts (remember that these are left-hand thread). Torque to 6-ftlbs.
35) Install the VANOS bolt plugs. Push the plugs securely into place using the flat-nose pliers.
36) Install the VANOS piston plug caps. Torque to 37-ftlbs.
34) Connect the four electrical harness plugs that were removed.
35) Install the oil line Banjo fitting, making sure that the mating surfaces are clean and there is a new sealing washer on each side of the banjo. Torque to 24-ftlbs.
36) Follow the valve cover gasket replacement video for replacement of the valve cover and new gasket.
37) Install the engine fan and fan shroud.
38) Reconnect the harness plug to the AUC sensor on the fan shroud and remount the auxilliary fan harness plug assembly to the shroud.