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VANOS Oil Pressure Accumulator Replacing
 
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Pelican Technical Article:

VANOS Oil Pressure Accumulator Replacing

Nick Czerula

Time:

2 hours2 hrs

Tab:

$260

Talent:

***

Tools:

22mm wrench, E5 Torx, 4mm Allen

Applicable Models:

BMW E46 M3 Coupe/Conv (2001-06)
BMW Z4 Coupe/Conv (2006-08)

Parts Required:

VANOS pressure accumulator, sealing washers, VANOS line

Hot Tip:

Work with a cool engine

Performance Gain:

Remedy fault codes and restore engine performance

Complementary Modification:

Replace pressure valve filter

To improve engine breathing at a variety of rpms, thus improving fuel efficiency, emissions and power, BMW engines are designed with VANOS, an acronym based on the German words VAriable NOckenwellenSteuerung or variable camshaft timing. Though a number of VANOS systems have been designed and implemented, the basic principle behind all of them is the need to change the relative timing between intake and exhaust valve opening. The VANOS actuator on each camshaft is supplied with engine oil under pressure; a solenoid controlled by the engine control module (ECM) retards or advances camshaft timing by modifying the supply of pressurized oil to the VANOS actuator.

Intake valves:

  • Retarded during idle, improves smoothness of idle.
  • Advanced during part-throttle acceleration, improves torque and emissions.
  • Retarded at full-throttle, improves high power production.

Exhaust valves:

  • Retarded during deceleration so that more exhaust can stay and mix with the cylinder charge, thus diluting the mixture, lowering combustion temperature and reducing NOx in the exhaust. This is similar to the effect of exhaust gas recirculation (EGR).
  • Advanced during warm-up phase in order to allow rapid warm-up and more efficient operation of catalytic converters.

BMW S54 engines utilize one main VANOS (variable camshaft timing) solenoid, mounted to the front of cylinder head. They are responsible for direct oil flow to the VANOS actuator. The VANOS oil pressure accumulator provides a constant pressure for start-up and when pressure assistance may be needed. You can check pressure using a BMW scan tool, should be in the 29 to 43 Bar range, if not the accumulator is likely faulty. However the most common failure is always an oil leak.

When replacing the accumulator, it is a good idea to replace the oil line and oil line heat shield, in case it has debris in it. This will require removal of the exhaust manifolds, where replacing the accumulator can be done from below.

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability.

Vehicle models change and evolve as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Questions or want to add to the article? Leave a comment below. When leaving a comment, please include your vehicle information.

The VANOS oil pressure accumulator (red arrow) provides a constant pressure for start-up and when pressure assistance may be needed.
Figure 1

The VANOS oil pressure accumulator (red arrow) provides a constant pressure for start-up and when pressure assistance may be needed. You can check pressure using a BMW scan tool, should be in the 29 to 43 Bar range, if not the accumulator is likely faulty. However the most common failure is always an oil leak.

Place a drain pan under the front of the engine.
Figure 2

Place a drain pan under the front of the engine. Then, remove the 10mm VANOS line fastener (red arrows). Next, remove the 14mm VANOS banjo bolt (blue arrow). Be prepared to catch any dripping oil. Remove the fastener slowly and cover it with a rag while unscrewing.

Remove the VANOS line (red arrow).
Figure 3

Remove the VANOS line (red arrow). Then reinstall the banjo bolt with a sealing sleeve (blue arrow) to prevent debris from entering the VANOS unit. Then seal the VANOS line with a cap. I use rubber caps and make the sleeve out of a rubber cap, cutting the top off.

Remove the engine splash shields.
Figure 4

Remove the engine splash shields. See our tech article on engine splash shield removing. Working at the steering rack, remove the 10mm hose loop mount (red arrow) fastener.

Lift the hose loop up (red arrow) and place it out of the way.
Figure 5

Lift the hose loop up (red arrow) and place it out of the way. You now have access to the accumulator from below. The following steps will show it being replaced from above, as if you had to replace the oil line as well. If replacing from below, you can use the same steps, working in a more restricted space above the steering rack.

Remove the exhaust headers.
Figure 6

Remove the exhaust headers. See our tech article on exhaust headers replacing. You now have access to the accumulator (red arrow).

Working at the top of the accumulator, remove the 14mm banjo bolt (red arrow).
Figure 7

Working at the top of the accumulator, remove the 14mm banjo bolt (red arrow). Inspect the oil line heat shield (blue arrow), replace if necessary with the oil line.

Working at the side of the accumulator, loosen the 10mm bracket pinch bolt (red arrow).
Figure 8

Working at the side of the accumulator, loosen the 10mm bracket pinch bolt (red arrow).

Loosen the 10mm bracket pinch bolt (red arrow) until is it out as far as shown, do not remove it.
Figure 9

Loosen the 10mm bracket pinch bolt (red arrow) until is it out as far as shown, do not remove it. Pop open the bracket until it stops at bolt head (blue arrow).

Twist accumulator to free bond of runner insulator and remove from vehicle.
Figure 10

Twist accumulator to free bond of runner insulator and remove from vehicle. Be prepared to catch any dripping oil in a pan.

To replace the oil line, remove the final 10mm fastener at the front of the timing cover.
Figure 11

To replace the oil line, remove the final 10mm fastener at the front of the timing cover. Then, pull the oil line out through the top of the engine, feed new line in from top of engine.

Reverse steps to install new accumulator, transfer rubber insulator (red arrow) over to new accumulator.
Figure 12

Reverse steps to install new accumulator, transfer rubber insulator (red arrow) over to new accumulator. When installing, accumulator will drop into bracket until it hits lower stop, then tighten clamp pinch bolt. Be sure to replace all the sealing washers and change your engine oil. Follow the instructions on the old unit (blue arrow) for proper disposal.

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Page last updated: Fri 12/2/2016 03:04:08 AM