BMWs are great vehicles with a lot of positives, but if you have owned one long enough you have probably witnessed first-hand one of the most common problems associated with these vehicles: a ticking noise coming from the engine bay. What causes a BMW to make a ticking noise, and is it a serious problem or just a minor annoyance?
A BMW ticking noise is most commonly caused by faulty hydraulic lifters. Ticking hydraulic lifters are common on higher mileage and poorly maintained BMWs, but they do not present a serious problem to the vehicle. Other causes of ticking noises include VANOS failure, a loose spark plug, or a faulty pulley. With the proper tools, diagnosis is fast and relatively simple.
Let’s take a deeper dive into the kinds of things that can cause a ticking noise in your BMW. Let’s also look at how to diagnose these causes and let’s determine how serious a ticking noise is for your BMW.
What does a ticking noise mean?
If you don’t work on your own vehicles often you might be surprised to learn that DIYers and mechanics attribute different meanings to different sounds and we describe them accordingly. A “tick” is distinctive from a “knock” or a “marbles” sound. A “knocking” noise often (but not always) indicates a serious problem with the engine, most infamously a rod knock, and a “marbles” sound typically indicates a faulty VANOS.
The subject of this article is what to do and how to diagnose a ticking noise coming from your BMW, but it was important to first point out that different problems in your engine bay will produce different noises.
What causes a ticking noise?
Faulty hydraulic lifters
Google “BMW ticking noise” and it’s certain that you will see a dozen forums complaining about loud lifters. Hydraulic lifters are an integral component to your BMW, they basically create space for components in your engine to expand and contract under normal operation.
Unfortunately inadequate lubrication inside your engine (oil) will quickly turn this important engine component into an annoying part of your daily drive.
The good news is that loud lifters are a common feature of BMWs with a little age in them and there is nothing to suggest that ticking lifters will cause damage to your engine. In fact, every BMW I have owned with over 100,000 miles had a lifter tick, it’s something that most used BMW owners get used to.
Common symptoms of a ticking lifter include:
- 1) the ticking is most pronounced after a cold start and while the car is idling
- 2) the ticking disappears as you press down on the accelerator or after the vehicle has warmed up
- 3) the ticking noise sounds like it is coming from the top of the engine and right beneath the valve cover
- 4) the ticking noise decreases or completely disappears briefly after changing the engine oil.
How can you fix a hydraulic lifter tick?
The first and most simple solution to a lifter tick problem is to perform an “engine flush”. This is basically just an oil change with an additional step or two. Engine flushes certainly are not full-proof solutions to hydraulic lifter ticks but they will often fix a mild lifter tick temporarily and sometimes permanently.
The goal of an engine flush is to clear out some of the gunk and sludge that has built up inside of the engine. Many professional BMW mechanics recommend that owners perform engine flushes on high mileage BMWs.
Whenever someone refers to an “engine flush” they could be referring to a few different things. Some people use harsh cleaners and/or high pressure steam to try and clean out the insides of the engine.
My engine flush entails pouring half a can of Sea Foam Motor Treatment into the engine, idling the vehicle for five to ten minutes, and then proceed how you would for a normal oil change. You can view a visual aid here.
If the engine flush does not silence your lifter tick you can also try one of the many aftermarket additives that are available. I personally do not use lifter additives because you have to be careful about who you purchase your additives from. You can check out several lifter additive videos here.
If none of these solutions work your last option should be to replace the hydraulic lifters. Hydraulic lifter replacement is a considerable repair and is not recommended for novice DIYers. Lifter replacement requires several special tools to hold the engine in place, hold the camshafts in place, and remove the VANOS.
As I mentioned previously, if it comes down to replacement or live with noisy lifters, most BMW drivers opt to live with noisy lifters. Ticking hydraulic lifters have not been found to cause any drivability problems or excess wear inside of the engine. For these reasons, noisy hydraulic lifters are annoying, but they will not force you to make an expensive repair.
VANOS failure
The infamous VANOS rattle is a common problem on BMWs. A VANOS rattle is distinct from the ticking noise that you will hear from a loud hydraulic lifter, however, for the average driver unfamiliar with these various components you may not be able to distinguish the two. Here is the Vanos rattle noise.
VANOS is a German acronym which translates to “variable camshaft timing”. The VANOS unit is located in front of the engine on both camshafts. The unit(s) adjust the intake and exhaust camshafts. This allows for a smoother idle and more power. VANOS was first introduced in 1992 and it is standard on all BMWs today.
The VANOS rattle is more serious than a ticking hydraulic lifter because it will actually have an impact on your engines performance.
Common symptoms of a faulty VANOS include:
- 1) loss of power and torque (mainly in the lower RPM)
- 2) higher fuel consumption
- 3) engine hesitation and rough idle
- 4) check engine light
- 5) Rattle that sounds like “marbles in a can”
How can you fix a VANOS failure?
Unfortunately the only way to fix a VANOS failure is to replace the faulty part. A VANOS failure, unlike a loud lifter, is not something that you want to sit on. VANOS replacement will require you to remove the valve cover, lock the engine in place, and lock the camshafts in place. The procedure will require specialized tools and is not recommended for the beginner DIYer.
If you believe that your VANOS has become faulty you should determine whether you want to replace it yourself or have a professional perform the repair, and do not procrastinate.
Loose spark plug
Spark plugs can and sometimes will become loose on BMWs. This can happen on a spark plug that you recently installed and it can happen out of nowhere on an old spark plug. The most common cause of a loose spark plug tick is that the spark plug was recently installed but not to the recommended torque spec.
Spark plugs provide spark to each cylinder but they also seal off the engine. If one loosens up you will hearing a ticking noise generated by the engine internally.
How can you fix a loose spark plug?
Loose spark plugs on BMWs are extremely common after a DIYer has installed them, usually it just means that one or more of the plugs were not installed tightly enough.
- 1) The first thing you should do is ensure that the engine is cold. Spark plugs get extremely hot and so does the engine so wait until the engine cools off.
- 2) Next, pull the ignition coils off of each spark plug.
- 3) With the spark plugs exposed, attempt to hand-tighten each of them. If any of them are easily tightened by hand, then the spark plug was too loose.
- 4) Tighten all loose spark plugs, put everything back together, and start the engine.
If you had to tighten some loose spark plugs, you have likely solved your problem.
Faulty pulley
A bad pulley bearing or even a loosely bolted on pulley can make a loud and annoying ticking noise. Your BMW serpentine belt runs on pulleys which turn important components of your vehicle such as your water pump, power steering pump, air compressor, alternator, and of course your engine’s crankshaft.
When pulleys begin to go bad they will often make an annoying noise. Oftentimes you can zero in on the faulty pulley by using a mechanic’s stethoscope. A stethoscope is an extremely useful tool for pinpointing exactly where a noise on an engine is coming from.
How can you fix a faulty pulley?
A bad pulley bearing typically requires replacement of the entire pulley. Serpentine belt pulleys are typically relatively easy to replace and well within the skill level of most DIYers.
Like the VANOS, however, you should not procrastinate on the replacement of a faulty belt pulley. Pulleys often make noise before they completely fail. Pulleys can seize up eventually which will cause the serpentine belt to break off and leave your vehicle on the side of the road.
Conclusion
In this article we learned that a ticking noise coming from a BMW engine bay is most commonly generated by loud hydraulic lifters. Luckily, this is not a serious problem and many used BMW owners drive with ticking lifters. We also learned that engine bay ticking noises can also be generated by a bad VANOS, loose spark plug, or a faulty pulley. If your ticking noise is caused by any of these sources you should have a mechanic fix it or repair it yourself before you put the vehicle back on the road.