Why Is My BMW Engine Rattling?

There is nothing more worrying to a car lover than when you are driving around and suddenly a noise starts coming from the engine bay. Most car owners are not experienced enough to be able diagnose these sounds they are hearing. Sometimes the sounds are normal and sometimes they are not. Find out what qualified mechanics from Foreign Affairs Motorsport say are usually the most common noises you need to worry about when it comes to why you hear your BMW engine rattling.

Most Common Rattling Noises And Problems When Your BMW Is Idling?

When your car is idling and you can hear rattling noises this most commonly points to 3 problems that mechanics have found. Below are the different noises and exactly what you need to do when you start to hear them. 

1. Connecting Rod Noises are created by an excessive clearance between the crankshaft and connecting rod bearing surface. Connecting rods are the arm that connects the piston head to the crankshaft. When there is excess clearance between the crankshaft and connecting rod it can cause quite a noise. This is created by either low oil pressure – which will dry up the lubrication on the crankshaft – or bad oil maintenance like not changing oil on a regular basis. This in turn allows grime and grit to build up in the oil which increases wear and tear on your engine. This is remedied by getting a qualified mechanic to replace the connecting rod, and in extreme cases, the crankshaft as well.


2. Piston Pin (Gudgeon Pin) Noises are caused by lack of lubrication and excessive clearance between the piston pin and piston. This issue can result in low oil pressure which will create other issues in your engine. This is remedied by replacing the piston. 


3. Overheating is a problem that will create a clicking or rattling noise in the engine compartment. This could be caused by many different factors such as low oil levels, low oil pressure, and cooling problems. This is definitely a problem you need to go see your mechanic about – if an engine overheats too much it could cause the bearing and crankshaft to seize completely which becomes very costly to repair.

The rule of thumb is if you hear a noise that you haven’t heard before when your car is idling it probably is something that needs to be checked out. The best option is to visit a BMW approved motor mechanic as soon as possible.

Most Common Engine Noises You Need To Be Concerned About When Accelerating.

If you hear a rattling noise when you are accelerating then this is definitely a friction problem. This could be a simple fix such as tightening or replacing your engines various belts. You can do a simple check by dropping some water on the belts and revving the engine. If this doesn’t quieten down the noise you could have a more serious problem on your hands.

1. Bad or Faulty Water Pumps have 2 areas that can be the cause of rattling – the accessory belt and the bearing. General wear and tear will cause these items to give in. You might also see your engine temperature rising above normal if this has happened. If this is the case you need pull over and turn off the engine immediately to allow it to cool down or it could cause serious damage.


2. Bad Alternator Bearings which are inside the alternator could be another cause of rattling. These bearings work through being rotated by the rotor to charge your battery and run electrical components on your car. If these are starting to go you will also notice your car having some trouble starting and a rattling grinding noise coming from the front of your car when accelerating. If this is not checked soon you will more likely get stuck and your BMW won’t start.

It is definitely not the best thing to hear a noise when you accelerate as this usually will lead to even bigger problems down the line. The first time you notice these noises it’s a good idea to get down to your nearest approved BMW mechanic to get a checkup for your engine.

There are some other general problems which will make a noise all the time. Loose engine mounts will always cause a noise as the engine is not securely fitted allowing too much movement. This movement could cause some extreme damage and would be very costly if left too long.

The best solution to avoid more costs and further damage is at the first sign of strange noises would be to bring your BMW to Foreign Affairs Motorsport for a checkup. Our qualified mechanics are certified to work on BMW’s and we have the most updated diagnostic equipment to help find any problem and repair them to the highest standard.