Bad Oil Cooler Symptoms, Causes, and How it Works

The oil cooler plays a vital role in the vehicle’s engine cooling mechanism, aiding in managing the engine oil’s temperature. With the passage of time, the oil cooler may suffer wear and tear, leading to different signs that can impact the engine’s efficiency and lifespan. This article explains the bad oil cooler symptoms, causes, and its replacement cost. 

What is Oil Cooler?

An oil cooler is a part of the vehicle that uses engine oil as a coolant to cool the mechanical parts of the engine.

oil cooler

In contrast to the water-based cooling system, the oil cooler is designed as a small radiator. The main function of the oil cooler is to reduce the vehicle engine temperature while driving. It only works during the operation of the vehicle.

Cooled oils have many uses as heavy-duty transmission oils. An engine with a cooling fan has the ability to quickly cool the oil-based and water-based radiators.

Due to the oil cooler’s role as an extra cooling device, the high temperatures of the engine significantly reduce when it is applied to an air-cooled engine. Due to the oil coolers, the service life of the engine significantly extends. Heavy trucks take full advantage of the oil cooler and help put more pressure on the drivetrain.

Improved cooling allows heated engine oil to run effectively at lower temperatures, reducing the chance of early failure. The degradation of oil loss reduces the functionality of the engine oil; due to that, it doesn’t properly cool and lubricate the engine.  

Working Principle of Oil Cooler

The engine oil cooler is one of the most important parts of the engine. The main function of the engine oil cooler is to properly cool the engine oil and the engine parts.

Working of Oil Cooler

The oil-to-air cooler is installed in the radiator front. The oil coolers work during the operation of the vehicle. When the vehicle runs, the oil cooler activates. As a result, the engine oil quickly gets the coolest fresh air from the cooling fans. In maximum systems, the oil leaves the engine in the form of a “sandwich” adapter.

The adapter installs between the engine block and oil filter to allow hot oil to pass through the oil filters. As the hot oil passes through the filter, then it flows by the oil cooler before flowing back to the engine to repeat the process. Some adapters have a thermostatic regulator that stops the flow of oil until a certain temperature is reached.

Few vehicle cooling systems have a remote control that forms the base of the oil filter and an extra adapter that contains the existing oil filters. The existing oil filter connects to the plumbing hose that connects the remote filter base to the radiator.

For vehicles that do not have enough space in the radiator front, the manufacturer provides radiators on other parts of the engine. Some have their own cooling fans.

Symptoms of a Bad or Failing Oil Cooler

As the engine oil cooler goes bad, it produces one of the below-given signs:

1) Oil Leaks

Oil leakage from the oil cooler adapter is one of the most common symptoms of a bad engine oil cooler.

Oil leak from oil cooler

The system has two oil cooler adapters:

  1. One adapter links the cooler to the oil lines
  2. The second adapter transfers the cooled oil back to the oil sump.

As the adapter goes bad, it may lead to oil leakage from the engine. If the oil leakage is very low, you may observe an oil puddle at the engine bottom. You may also notice the oil leakage on the ground behind the vehicle.

If you notice an oil leak under the vehicle, you must immediately contact a professional mechanic. If you ignore the oil leakage, it may lead to engine overheating.

Therefore, you must take the leakage failure seriously, as the entire engine has lost enough lubrication. This problem can lead to increased engine temperatures and premature component wear.

Read More: Low Engine Oil Symptoms and Causes

2) Engine Overheating

Engine overheating is one of the major symptoms of a bad engine oil cooler. As we discussed, the cooler prevents the engine from overheating.

engine overheating

When the cooler fails, it doesn’t properly cool the engine oil, which leads to engine overheating.

3) Coolant Leaks

When an oil cooler fails externally, it may cause the coolant to leak from the engine. The leakage of the coolant may range from a minor puddle to a continuous flow of coolant beneath your car.

Coolant Leaks

The coolant leaks due to a malfunctioning oil cooler may lead to various issues like engine overheating. Hence, it is important to contact a mechanic to diagnose and address the issue in a timely manner.

Read More: Coolant Leak Symptoms and Causes

4) Oil in the Cooling System

When the oil cooler adapter leaks internally, the engine oil starts going into the cooling system.

Oil in the Coolant

When the adapter is damaged internally, the oil pressure becomes higher than the internal pressure of the cooling system during the engine operation. Due to the pressure difference, oil is pushed into the cooling system. Ultimately, this may quickly reduce the oil level and cause severe engine damage.

Read More: Bad Cooling System Symptoms and Causes

5) Coolant in the Oil

Oil and Coolant Mixture

The coolant in the engine oil mixes when the engine doesn’t work, but the cooling system is pressurized. In such conditions, the cooling system forces the coolant into the oil sump. Excessive oil levels in the sump may badly damage the engine if the crankshaft hits the oil during its rotation.

6) Reduced Engine Performance

Poor Engine Performance

The reduction in engine performance is one of the main signs of a bad oil cooler. This is noticeable in slow acceleration and low top speed. The engine also shows high temperatures on the heat gauge during operation. This is because the engine doesn’t cool down fast enough and overheats.

7) Higher Temperature on the Temperature Gauge

Temperature Gauge

The temperature gauge shows the engine temperature. It is located on the car dashboard. The higher temperature on the temperature gauge shows that your engine is not cooling properly.

The engine may overheat due to different reasons, and a bad oil cooler is one of them.

8) Black Smoke

Black Smoke from the Exhaust Pipe due to a bad oil cooler

When the oil cooler of your vehicle goes bad, the oil may leak into the engine’s combustion chamber. This results in the emission of thick black smoke from the tailpipe of your vehicle.

When your vehicle emits black smoke, it is essential to switch off the vehicle immediately, as it could potentially cause damage to integral engine parts.

9)  Excessive Vibrations

In addition to the black smoke emissions, the entry of oil into the engine cylinder due to a faulty oil cooler may generate vibrations.

These vibrations are caused by irregular combustion in the combustion chamber, which could potentially harm other parts of your engine if not addressed promptly. Therefore, you should engage a qualified mechanic to inspect and rectify the problem at the earliest.

10) Check Engine Light

The latest vehicle models come with various sensors. The function of these sensors is designed to identify issues relating to the cooling system and the engine oil.

Check engine light flashing

When there is something goes bad with the oil cooler, the vehicle’s main computer triggers a warning light on your dashboard. These warning lights could include the engine temperature warning light, the oil pressure warning light, or the check engine light.

In case any of these lights illuminate, it’s crucial to contact a professional to fix the issue.

Read More: Causes of Check Engine Light Flashing

Causes of Bad Oil Cooler

Corrosion, poor maintenance, wrong installation, and wear and tear are the most common causes of a faulty oil cooler. When the cooler becomes faulty, you need to replace it to prevent your engine from damage.

The following are the common causes of a bad engine oil cooler:

1) Corrosion

As time progresses, the oil cooler can suffer corrosion owing to contact with moisture and other corrosive substances. This may lead to the deterioration of the cooler, ultimately resulting in damage.

2) Wrong Installation

Incorrect installation of the oil cooler may also lead to damage due to factors like excessive vibrations. Hence, it is of utmost importance to get the oil cooler installed by a mechanic who is well-acquainted with the specific vehicle model.

3) Blocked or Clogged Passages

The oil cooler of a vehicle contains multiple channels for the flow of oil. Over time, these channels may get obstructed or blocked. Such blockage can stop the oil flow, triggering overheating of the oil cooler and consequent damage.

4) Poor Maintenance

Similar to all other car parts, proper maintenance of the oil cooler is necessary to guarantee its optimal functioning. A lack of proper maintenance may result in its damage and premature failure.

5) Physical Damage

Generally, the oil cooler of your vehicle is usually situated in a susceptible location of the engine, making it prone to damage from road contaminants. Even minor damage or puncture may also lead to oil leakage from the cooler.

Advantages of Engine Oil Cooler

  1. It helps to cool the hot oil.
  2. It helps to properly cool the engine parts.
  3. The engine oil cooler ensures efficient oil cooling before pumping it throughout the engine.
  4. It prevents the engine from overheating.
  5. It is very easy to install.
  6. It improves the performance of the engine.
  7. Oil circulation is controlled and efficient.
  8. The oil coolers reduce the use of the water-cooling system due to that they prevent the engine parts from corrosion.

Disadvantages of Engine Oil Cooler

  1. It uses oil instead of water. The oil is flammable, which increases the risk of fire.
  2. These systems consume a high amount of oil for efficient operation.
  3. They require regular maintenance for efficient working.
  4. The failure of the engine cooler oil leads to engine overheating.
  5. The engine oil is expensive.

Engine Oil Cooler Location

Typically, the oil cooler is located between the main radiator and the grille to ensure it receives maximum airflow.

Oil Cooler Location

However, certain vehicles may require mounting it lower behind the front valance. Additionally, some oil coolers need to be positioned upright, while others can be installed on their side.

How To Test Oil Cooler

FAQ Section

What is the replacement cost of the engine oil cooler?

The replacement cost of the oil cooler varies according to the vehicle model and the type of brand. The average replacement cost of the oil cooler is from $520 to $600. In this cost, the cost of the parts is from $350 to $400 while the labor cost is from $1170 to $200.

What happens when an oil cooler fails?

A malfunctioning oil cooler may expel all the coolant from the engine, increasing the chance of engine overheating, which in turn could cause potential engine damage. In the event of a major leak, you may spot coolant puddles under your vehicle.

Can a faulty oil cooler cause the oil in the coolant?

Yes, a faulty oil cooler is one of the most common causes of oil in coolant.

What happens if the oil cooler gasket fails?

In case your oil cooler gasket is damaged or worn out, your vehicle’s performance will start to reduce. This reduction in performance may observe as poor acceleration or poor fuel economy.

When should I change my oil cooler?

With the application of proper maintenance practices, the engine oil cooler of your vehicle should ideally last for the entirety of the vehicle’s lifetime. Therefore, without any accidents, there would be no need to replace your oil cooler for many years.

Can you drive with a bad oil cooler?

Yes, it’s possible to continue driving for a brief period with a faulty oil cooler, but you shouldn’t drive for a long time. If your oil cooler isn’t working properly, it’s still okay to drive it gently as long as you don’t push it too hard. However, you should get it fixed as soon as possible. Continuing to drive with a faulty oil cooler for a long time could seriously harm your vehicle and lead to permanent damage.

What is the main function of an oil cooler?

The main function of the oil cooler is to cool the oil that flows through its passages. This cooling process helps extend the lifespan of both the transmission and the engine.

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