If you drive or own a BMW or MINI vehicle, there’s a good chance you’ve heard the acronym VANOS in relation to the car's performance, servicing or repair. The system brings some great benefits to the vehicle but can be prone to failure, and expensive to fix. 

We’ll take a look at what the system does, what causes failures and how much VANOS systems cost to fix.

What is a VANOS system? 

A Vanos system is a variable camshaft timing system in BMW cars; VANOS stands for Variable Nockenwellensteuerung which is a GERMAN translation of a variable camshaft system. BMW developed the system in the early 90s and it is now seen on all BMW petrol-engined vehicles. 

VVT systems in general use some kind of electromechanical or hydraulic mechanism to alter the timing of the opening and closing of the engine’s valves. Manufacturers such as Honda, Toyota and VW all have their own brand of VVT systems. 

VANOS differs slightly in its application from other VVT systems as it combines hydraulic and mechanical systems. The implementation of the former is often the cause of headaches for many BMW owners. 

How does a VANOS engine work

Overall, an engine with VANOS differs very little from one without, the VANOS unit can be seen as a protrusion from the cam cover atop the engine. On modern BMW cars, the VANOS unit is more integral, and often hidden by a plastic engine cover. 

The VANOS system uses two cam gears instead of one, per camshaft. One is driven as normal by the engine via the cam belt or chain, and the other is driven by a hydraulic clutch system.  

When the computer detects the engine is in a specific set of parameters of RPM and load, a hydraulic solenoid valve opens to allow oil from the engine to activate the VANOS cam gear. 

On early versions of the system, the second camshaft drive was at a fixed speed, meaning the valve timing altered from one set position to another. On modern systems, it is infinitely variable, the equivalent to VVT-i systems made by other manufacturers. 

Valve timing is adjusted only at high engine speeds, this is done to both extend the period for which the valve is open and to alter the time in the engine's cycle it begins to open.  

Most VANOS or VVT systems begin to activate at between 2,500 and 3,300 RPM on most models. The threshold depends on engine load, speed and throttle position.  

VANOS systems differed from its competitors when introduced as they could activate gradually, instead of in a binary fashion as with Honda engines for example. This can be considered a benefit or a drawback depending on the circumstance.

Double or Single VANOS

After the improvements to efficiency and power gained from adding the VANOS valve timing system to the engine's intake camshaft, BMW developed what is known as the double VANOS system. 

This adds a control system similar in design to the single VANOS unit, to the exhaust camshaft, allowing the ECU to now control the timing of both the intake and exhaust valves. 

Do all BMW engines have VANOS?

Other than diesel engines, almost all BMW engines since 1993 have some variation of a VANOS system. With the exception of a few select models that still used the older version of a BMW engine after 1993. 

What years did BMW use VANOS?

Introduced in 1992, the BMW M50 engine was the first to be introduced as the M50B20TU - the B20 designating a 2.0L displacement, TU is used on all BMW engine codes to identify engines fitted with VANOS. 

The M50 engine was used in both the 3 series and 5 series of the era from 1992 onwards. 

Double VANOS was first used in 1996, on the S50 engine found again in the 3 and 5 series, along with the famous E36 M3. 

What causes VANOS failure?

BMW’s innovative VANOS system allowed their petrol-engined cars to achieve amazing efficiency and performance figures. But with some systems now reaching 30 years of age, it’s handy to know how to check if a VANOS system is starting to fail.  

The relatively complex nature of the VANOS system is usually its downfall. It is a common issue for older BMWs for the system to not work correctly, and the specialism required to fix them can make them a costly repair. If you’re worried about the cost, Bumper can help you spread you repair and service costs into interest-free instalments at 1000s of dependable repairers across the UK.

Often, the culprit of such failures is the ageing of the oil seals that control oil flow through to the VANOS unit. Rubber seals degrade over time, and seals that are not continually exposed to oil will perish faster than normal. 

With the VANOS unit sitting at the top of the engine, all residual engine oil used when running the engine will drain to the sump within an hour or so. This leaves the seals to dry out when the car is not in use.

Another regular component for replacement is the VANOS solenoids themselves, these control the flow of oil to the VANOS system, and when they fail can cause multiple problems.

VANOS system failure symptoms

As the system uses complex mechanisms that are driven by the engine, any wear or improper function can usually be heard or felt whilst the engine is running. With this in mind, there are other symptoms to be aware of. 

VANOS system ticking

When at idle and especially upon startup, the VANOS unit may make a ticking noise, some owners remark it makes the engine sound like a diesel, this is often the fault of worn seals in the VANOS unit.  

Low on power

Variable valve timing enables the car to retain power low down in the rev range, whilst allowing the engine to reach a higher peak output at higher RPMs.

If the VANOS system on your BMW is failing, you may notice a distinct lack of power, especially when below 3,000 RPM 

Rough Idle 

Because the cam timing will not be properly regulated, the ECU cannot accurately control the ignition and fueling at any given RPM, this is most prominent at very low engine speeds.  

When idling, the car may sound particularly rough, as if a misfire is occurring, as well as being erratic in its speed, i.e. raising and lowering its idle speed at random. 

Engine fault codes

When the ECU on cars post-1996 detects a fault, it is usually logged in the computer’s memory, and displayed on the dashboard. This may be from an idle sensor, camshaft/engine speed sensor or emissions sensor.  

Indication of this will usually be an engine management light, and the code stored will likely correspond with one of the components in the VANOS system. Common fault codes are: 

• 2A82: Vanos intake solenoid 
• 2A87: Vanos exhaust solenoid 
• P1520: Camshaft position actuator, exhaust 
• P1523: Camshaft position actuator is jammed, exhaust 
• P1397: Camshaft position sensor B 

VANOS system maintenance

Like any ancillary system on a vehicle, maintenance is required to keep the VANOS working properly.  

Common failure points, as mentioned include the solenoid valves and rubber seals. These are therefore the most important maintenance components.  

Seal kits are available, and it is recommended they are replaced every 50,000 miles. If your car does not cover much mileage but is an older model, it may be worth replacing before these milestones.  

Solenoid Cleaning 

To avoid complete solenoid failure, it is recommended that the solenoid valves for both the intake and exhaust VANOS systems are cleaned at semi-regular intervals.

These can become clogged with contaminants and over time, become slow or completely unresponsive. Any BMW specialist garage should be well aware of this procedure. 

BMW VANOS repair cost

The average VANOS repair cost is between £300 and £2,000. At the lower end, the rubber seals are relatively easy to replace, but if the unit itself is faulty, this can be an expensive job in parts and labour. 

Whether your entire VANOS system needs replacing, or your car just needs the seals replenished, the cost can vary greatly from vehicle to vehicle, as well as depending on your location.

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