BMW is a brand with a long history of revolutionary innovations that keep the company ahead of the curve. Their vehicles make their drivers feel elite, as if they belong to an exclusive motoring club. There’s a lot to love about BMW, such as their smooth drive and luxury. The innovation that is at the heart of the amazing BMW driving experience is the VANOS system. In this article, we will take a closer look at the system, its most common problems, and discuss what the annoying rattling from the VANOS system can mean for your BMW.
What is the VANOS system?
VANOS is an abbreviation of the German words “VAriable NOckenwellen Steuerung.” This was introduced in 1992 as BMW’s version of the engine variable valve timing unit. This system is able to reflexively open and close the engine intake and exhaust valve, which provides greatly-improved engine performance, notably in regards to torque and smooth idling. The VANOS system is also able to monitor the oil flow within the engine, using its solenoids, and will allow for more precise timing.
Types of VANOS System
There are three types of VANOS system that your BMW may have, and being able to identify the type that is within your car may help you get to the root cause of your rattling problem:
1992-2000 in 6-cylinder M50, M52, & S52 engines
1999-2002 in V8 M62TU engines
1999-2005 in 6-cylinder M52 TU, M54, & S54 engines
2004-2010 in 6-cylinder N54
Double VANOS with Valvetronic
2004-2010 in 6-cylinder N52 & N55
2004-2010 in V8 N62 & N62 TU engines
2005-2015 in V12 N73 & N74 engines
What causes the rattle?
A rattling VANOS unit is quite a common problem and is typically caused by the wear of the variable valve timing helical gears. These gears are slanted and are found in three places: the camshaft, the camshaft sprocket, and the splined shaft, which is directly connected to the VANOS system. When these gears become loose, they can begin to vibrate, knocking into other parts at certain RPM’s, thus creating the annoying rattle.
BMW are constantly trying to improve upon their systems year after year. They have made some modifications to the VANOS unit to try to reduce the risk of a rattle developing. The VANOS piston bearing was modified first with little success. Next, this was extended but actually resulted in an increase in reports of rattling. Finally, the bearing was decreased, which helped to resolve the issue. Since then, far fewer cases of rattling have been reported.
Engines with higher performance cam, also known as lift, are at an increased risk of developing VANOS rattling. They are likely to experience a worse rattle than vehicles without this.
What are the other symptoms and what vehicles are susceptible?
Typically, a rattle that is being caused by the VANOS system will occur when your camshaft is between 1800-2200 RPM. The rattling can also occur when idling too, but not always. Due to BMW’s experiments in reducing rattling, some models are more prone to VANOS rattling than others, with some of the top culprits being:
- The 3-series including the E46 320i, 323i, 330i
- The 5-series including the E39 520i, 523i, 530i E60 530i
- All models of Z3
Will the rattle harm my car?
Other than being quite annoying, a VANOS rattle is usually harmless. It is safe to ignore it, if you can. However, you should keep an eye on it for any changes. If the rattle is accompanied by any of the symptoms below, then it is best to bring your BMW in for repairs, as these signal a more general issue with the VANOS system:
- Power/torque loss
- Engine struggling at lower RPM
- Rough idling
- Reduced fuel economy
- Poor cold starts/stalling in cold weather
- Warning light illumination
- Limp engine after acceleration
Seeking Repairs at Import Car Center
Drivers living in or around Colleyville, Keller, Southlake, Westlake, and Grapevine, TX who have BMWs that are struggling with VANOS rattling are in luck. Import Car Center are on hand to help. We are specialists in Import automobiles, and no job is too big or too small or beyond our extensive knowledge base. Stop by today or call us for an appointment. We are happy to speak with you about your concerns regarding your BMW.
* BMW M4 Car image credit goes to: Wirestock.