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4 Common Mercedes CLA Problems You Should Know!

What kind of problems does a Mercedes CLA usually have? In this blog, we’ve outlined the most important things you should watch out for when you’re in the market for a CLA. However, let’s first start with a quick answer.

Common problems for all generations of the Mercedes CLA are oil leaks from the gearbox, a burning oil smell in the cabin, and having severe difficulties with aligning the car properly. Finally, the 2016 – 2020 CLA has had a large recall for debris stuck in the fuel injectors.

That was the most straightforward answer possible. In the article below, we’ll discuss every problem in detail. This means that, no matter what model year you’re looking at, you should know what issues you can expect, what causes them, and how they should be fixed. Read on!

1. Gearbox Leak Problem

Finding a leak on your Mercedes CLA is never comforting, and it is even less reassuring when it is a gearbox leak.

Gearbox leak is a common problem reported by many owners in their Mercedes Benz CLA.

If you have spot puddles or stains of oil on the ground beneath your car. Then it becomes imperative that you check your Mercedes CLA for any leak coming from the gearbox. To start, get under the car and find the source of the oil leak. If the leaking oil comes from the transmission, it must be from the gearbox sum or other surrounding components.

Common culprits behind the transmission oil leak on the CLA are:

  • A wrongly screwed gearbox cap
  • Cracked or damaged transmission oil sump
  • Faulty torque converters (on automatic transmission)
  • Damages seals and gaskets

After discovering the different roots of a transmission oil leak on your Mercedes CLA, repairing this problem becomes essential. For this, you must first detect the exact source of the leak. In the case of small leaks, you can consider buying a sealing key that costs about $50 and is effective in small leaks.

However, identifying the exact underlying problem leading to the oil leak is complicated and requires a lot of expertise and labor. Hence you should take your CLA to the service station to inspect the issue. Overall, the technician will offer these solutions to cope with the leak –

  • Often, the technician will take apart the gearbox to detect the leak, necessitating more time and a high labor cost.
  • If a gasket is found faulty, the technician will replace it and will reassemble the gearbox.

To avoid the gearbox or transmission leaks on your Mercedes CLA, you should –

  • Perform regular oil changes for your gearbox.
  • Drain old gearbox oil frequently and fill in new oil.
  • Use particular additives for gearbox seals, which help restore the seals’ flexibility.

In worst cases, when the issue is irreparable, you might have to replace the complete gearbox of your Mercedes CLA. Replacing the gearbox of your CLA might include exorbitant costs.

Note that gearbox problems often lead to a replacement of the faulty part. Depending on the part and the varied labor costs, solving problems with the transmission leak can cost anywhere from $50 to $1800. 

Also read: The Complete Cost Of Maintaining A Mercedes-Benz

2. Car Smells Like Burnt Plastic

Reportedly, among quite a few problems with the Mercedes CLA. The issue of the car smelling like burnt plastic is common. In general, detecting a smell of burnt plastic or rubber is never a good sign. In reality, this could mean a critical malfunction of any internal component. 

Following are the different possible origins of the burnt plastic smell –

Transmission Oil

In most cases, the transmission oil is the primary source of the burnt plastic-like odor in the CLA. The purpose of transmission or gear oil is to lubricate various gearbox components, so the pinions and gears work correctly. However, it also has a second objective: to maintain the optimal temperature of the engine.

As time passes, the transmission oil loses its performance and would not lubricate the parts or control the temperature appropriately. This triggers the oil to heat excessively, resulting in the burnt plastic-like smell in your Mercedes CLA. It is a good idea to change the transmission oil in your CLA if you detect the plastic odor to avoid pre-wearing your gearbox or its vital components.’

To check the transmission oil for the burning smell, open the oil cap (when cold) and verify that the oil fluid is enough and should be reddish. If you find any debris inside and it is darker, consider replacing the transmission oil.

Accessory Belt

Though rare in occurrence. With time, wear and tear can cause the accessory belt in your CLA to degrade and no longer rotate correctly on its axis. This will lead to accidental friction that will trigger the plastic of the belt to heat and burn out. Thus producing a strong smell of burnt rubber or plastic in the engine bay of your Mercedes CLA.

To check the accessory belt for the burning smell, visually inspect the belt. If in a poor state, it might also produce a whistling sound. Moreover, if you find the accessory belt faulty, don’t think twice about replacing it.

A Body Component

Suppose your Mercedes CLA has been in an accident recently or in the past. Then, as a result, components near the front or rear tires like; bumpers, wheel arches, or other plastic body components might have disoriented from their original position. 

In that case, these damaged components might have been rubbing against the wheels giving off that burnt plastic-like smell.

To check the body components for the burning smell, inspect all the tires of your Mercedes CLA to ensure nothing is rubbing against them that could lead to a foul odor.

Hose Wear

This problem usually occurs in Mercedes CLA, a few years old, or has stayed for a long time without rolling. Storing your vehicle contrary to what you may think will trigger plastic parts in the car to wear more quickly.

Hoses are the components that are greatly affected by this phenomenon. The outer rubber of the hoses will disintegrate little by little as the fluid’s heat inside it rises. Moreover, it also might lead to complete breakage of the hose if the car is resting for a very long period. 

To check the hoses for the burning smell, visually verify that all the hoses are not frayed or melted. If found damaged, consider replacing them as it might cause the burnt plastic-like smell inside your Mercedes CLA.

3. Car Pulls To The Right

If you think that your Mercedes CLA is pulling to the right, your car might have some problem that needs attention. Usually, a car pulling in one direction, either left or right, is due to any of the following reasons –

Incorrect Tire Pressure

A minor difference in tire pressure is enough to pull your Mercedes CLA to one side. Moreover, incorrect tire pressure also leads to excessive tire wear. Consequently, you might have to replace them earlier. Thus, ensure that the tires on either side of the vehicle have correct tire pressure.

Dead Silent Blocks

Silent blocks on the Mercedes CLA are a suspension component, two metal bushings surrounding a rubber insert. The primary function of the silent block is to connect the suspension parts and damp vibrations between the nodes.

On the Mercedes CLA, silent blocks add to the comfortable ride quality due to the elasticity of the rubber, which serves as a damper among the suspension parts. 

If your CLA pulls to the right or the left, then your silent blocks are dead. When worn out, the silent blocks don’t contribute to the shock resistance and create a lack of stability in the steering, which in most cases causes the vehicle to lean on one side.

Inspect your silent blocks for any wear and tear to solve this problem. If found faulty, they should be replaced immediately to avoid the car pulling to the right or left.

Faulty Bearings

Another explanation for your Mercedes CLA pulling to the right can be your faulty bearings. In most cases, the bearings at the front go bad, giving rise to vibration and rolling noise and the trajectory issue.  

Furthermore, if the bearings are faulty, they will no longer work correctly and slow down the wheel’s motion on which they are fitted, which inevitably leads to the trajectory problem.

If you suspect bad bearings on your Mercedes, have them swapped to overcome the trajectory problem.

Faulty Suspension

Another possible reason for your CLA pulling to the right can be a faulty shock absorber. It doesn’t matter if the problem is of tired springs, damper cup, or twisted cylinder, every issue related to the shock absorbers can disrupt the usual behavior of your Mercedes Benz CLA.

Therefore, it is necessary to timely inspect the shock absorbers’ condition and parts.

A fault in the suspension system and its components leads to the trajectory problem, but it can also be the reason for any unusual noise coming from the suspension when you drive over bumps. 

Also, read Mercedes 4Matic Problems.

4. Problem Of Leaking Injector

Although rare, the problem of leaking injector on the Mercedes CLA needs immediate attention. If the injector in your CLA is leaking, you can easily spot oily/black drops along the sides of your engine. Moreover, other symptoms like abnormal black smoke and a troubled ideal also indicate a leak in the injector of your Mercedes CLA.

You should know that the injectors on petrol and diesel engines on the CLA are different. This is because of the difference in combustion between these engines that makes the injection dissimilar. But any leaking injector can bring about more severe engine problems in your vehicle. Thus it must be resolved.

Injector Leak On CLA Petrol Engine –

Generally, in the petrol engine on the CLA, the injection pressure varies between 3.5 bars (for indirect injection) to 120 bars (for direct injection).

It should be known that injector leaks are pretty infrequent in the petrol engine on a Mercedes Benz CLA. This is generally because there is a lower pressure in the petrol intake systems. Still, there are two common types of injector leaks that you can suffer. Furthermore, Mercedes did issue a recall for this problem in 2016 – 2020 CLA:

2016- 2020 platform vehicles with a gasoline engine, a leak may develop between the fuel rail and fuel injector due to trapped debris from the production process, which could affect the safety and emissions of the vehicle. Trapped debris might damage the seal between the fuel rail and fuel injector, which over the life of the vehicle, might result in a fuel leak into the engine compartment.

Source

Leakage From The Bottom Of The Injector

You may suffer a leakage from the bottom part of the injector of your CLA. If this happens, you can notice a leak at the junction with the engine and not with the rail.

Leakage From The Top Of The Injector

Sometimes, you may suffer a leak from the top part of the injector of your CLA. This is the part connected with the fuel rail, and an O-ring might be involved.

Injector Leak On CLA Diesel Engine –

Unlike petrol engines, which have spark combustion, diesel engines burn fuel through compression. This process usually generates much higher pressure in the diesel engine, as do the injectors. Thus, the pressure is more than ten times higher than the petrol engines with the direct injection between 1800 to 2000 bars. 

In the case of leaking diesel injectors on the Mercedes CLA, there are primarily three kinds of leaks –

Injector Return Leakage –

This leakage concerns the leakage of fuel when it returns to the injectors. The main culprit behind this leakage is the O-ring and its leaking plastic tip. 

Leakage From Injector Inlet

This leakage on the diesel engine injector happens when the inlet pipe deforms. In most cases, the lead would occur at the clamping point.

Leakage From Injector Base

The most annoying leakage; happens at the junction between the injector nose and engine that leaks at the copper seal. You will experience compression loss accompanied by air noise when this leak occurs.

Overall, to fix any leak from the injector on your Mercedes CLA, you will either have to repair or replace it. To avoid further damage, it is recommended to take your CLA to the service station to have the leakage inspected by a skilled technician.

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