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Old 11-24-2007, 11:45 AM   #1
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Join Date: Nov 2007
Location: Raleigh, NC
Posts: 1,295
My Ride: 528i 06/00
Vanos seals solution

As many of you know E46 6-cylinder cars are experiencing a vanos problem. A friend and I diagnosed this problem three years back. Hereís the link where we made our findings public. http://bimmer.roadfly.com/bmw/forums/e39/7494631-2.html

The double vanos in question is part # 11-36-1-440-142, and is found on 6-cyl engines M52TU, M54, M56. These engines are all found on E46 models. If you have an E46 6-cylinder (non-diesel, non-M3) then you have one of these engines and implicitly this vanos.
On M52TU cars, 99-00, the failing vanos is manifesting cold weather cold engine start idle jolts and possible stall. I expect most 99-00 owners have experienced this symptom. On cold mornings the DME utilizes the vanos to help warm up the cats to bring them to operating temperature faster. When the vanos malfunctions the DME reacts badly and causes the idle jolts and possible stall. This scenario was addressed in the subsequent engines M54 and M56 with a software patch to address the DME reaction to the failing vanos. There is also apparently an update to the M52TU software that also addresses the symptom.
The failing vanos will reduce torque and power, particularly in the lower RPM range (< 3K). Hiccups and hesitations are also experienced in the lower RPM range (< 3k). Owners are now also beginning to encounter fault codes caused by the failing vanos. These codes are all related to the vanos exhaust side.
P1520 (BMW 104, 0x68): B (exhaust) Camshaft Position Actuator (faulty reference value).
P1523 (BMW 106, 0x6A): B (exhaust) Camshaft Position Actuator Tight or Jammed (mechanically stuck).
P1397 (BMW 18, 0x12): Camshaft Position Sensor B (exhaust) Circuit.
The Camshaft Position Sensor (CPS) is a common failure. But if replacing the exhaust CPS (w/ OEM CPS) doesnít work then itís likely the vanos failure.

The vanos failure is due to deteriorating vanos piston seals. The seals are a combination of outer Teflon seal ring and underneath supporting O-ring. The O-rings are hardening, shrinking, and having flat top and bottom surfaces. This causes them to lose their supporting function to the Teflon seals. This causes the piston seal function to fail and in turn the vanos function to fail.
The OEM O-rings were tested for material makeup and were found to be made from Buna-N (Nitrile, NBR). This material is not compatible with the engine synthetic oil and high temperature. The high temperature in particular is causing its failure.

BMW was engaged for some period regarding this matter but has indicated they have no intention of addressing the issue.

The O-rings can be replaced with a better material to withstand the synthetic oil and high temperatures, but to replace the underneath O-rings the outer Teflon seals need to be removed and necessarily damaged. Thus the Teflon seals also need to be replaced in the process. The Teflon seals are significantly more expensive than the O-rings and need to be semi-custom manufactured. This has to be done in large volumes (thousands) to even approach a reasonable cost.
I have taken the initiative in the past two years to pursue this endeavor and have succeeded in reverse engineering the seals and producing a seals repair kit that addresses the vanos failure. Here is the post where I recently introduced this solution.

Here is the website for the company I created to vend the product: http://www.beisansystems.com
You will find more information there, including a repair procedure: http://www.beisansystems.com/procedu..._procedure.htm
The procedure currently addressed the E46 with the electric fan. I hope to update it soon to show the E46 mechanical fan. For now the E39 mechanical fan removal can be referenced.

The vanos seals repair kit currently costs $60, plus $5 US shipping. It addresses all the known vanos failure symptoms. Owners have also been quite please with the performance enhancements attained from the repair.
A new (rebuilt) vanos will solve the vanos failure, but a new vanos costs ~$500. Even more problematic, a new vanos still comes with the same failing Buna O-rings. Numerous owners have installed new vanos units only to have them fail again. I inspected my new vanos seals after 20k miles and found them to be significantly degraded.

I will be happy to answer any questions. Please take the time to read the information in the referenced links.
In the future, please direct your questions to the vanos forum referenced by the Beisan website.
Rajaie is offline   Reply With Quote
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