What Are the Symptoms of a Bad Oil Cooler?

A lousy oil cooler is a significant issue! It keeps the engine’s oil cool and at the correct viscosity level. If it’s not functioning right, performance and wear will suffer.

bad cooler

To detect if yours is off, look out for the following:

  • Oil leaking
  • Engine running hot
  • Smoke and steam
  • Loss of power or torque
  • Noisy and vibrating motor.

What is an Oil Cooler?

An oil cooler is a unit created to reduce and control the temperature of motor oil in an engine. It’s like a radiator with tubes connected to the engine block on one side and an external fan on the other. This is called a heat exchange system. It transfers heat from hot oil to a medium, such as air or coolant fluid. This lowers the oil temperature and helps prevent engine damage from too much heat. Oil coolers are used for high-performance and heavy-duty engines in race cars and commercial vehicles.

When an oil cooler fails, there can be many symptoms, including:

  • Higher oil temperatures while driving.
  • Loud noises like grinding or rattling are coming from the engine bay.
  • Visible exhaust smoke when accelerating or running at high speeds.
  • Dark greyish fluid underneath your car when parked.
  • Decreased fuel economy and less power due to clogged fuel injectors.
  • Impairments in components such as turbochargers that need cooled motor oil to work well.

Causes of a Bad Oil Cooler

Oil coolers are essential for the functioning of your vehicle’s engine! It regulates oil temperatures and keeps the engine running smoothly. Nonetheless, a faulty oil cooler can cause many issues with your machine.

This article will discuss possible causes of a bad oil cooler and how to detect it:


Leaking is the most common cause of a bad oil cooler. It needs to be sealed properly for it to work. Hot engine oil can escape if the seal breaks, and coolant can enter your internal parts. This will cause wear on the system and reduce cooling.

Inspect the radiator coolant reservoir and along the hoses for signs of leakage like dampness, green liquid, or drips. A pressure tester can be used to check for leaks. Or, have a professional do it if you don’t feel comfortable.


A clogged oil cooler is often the cause of a broken one. This causes engine overheating due to blocked cooling fluid. Signs of this are poor engine performance, high temps, and a check engine light.

Clogging can be caused by bad fuel quality, corrosion, and aging fluid deposits. Incorrect installation or servicing of an aftermarket cooler can also reduce flow rates.

Inspect the unit for blockages if you experience temp increases or reduced performance. You must clean or replace it to restore performance if it’s clogged.

Loose Connections

Oil cooler connections can loosen due to age or vibration. This leads to overheating and loss of power and performance. You may also spot oil or antifreeze leaks near the oil cooler.

To avoid this, check the connections often for tightening and security. If you find them loose, pull them right away. This will keep your engine running correctly.

Symptoms of a Bad Oil Cooler

Oil cooler failure? Watch out! Symptoms can include:

  • an over-heated engine;
  • decreased oil pressure;
  • fluid leaks; and
  • a check engine light.

Let’s look closer at these signs of a bad oil cooler. Act fast to take the right action.

Overheating Engine

Is your engine running hotter than usual? It could be a sign of a bad oil cooler. This happens when the engine oil can’t get rid of its heat. The excess heat accumulates in the engine, leading to an increase in temperature.

Other indicators of an issue with the oil cooler include:

  • low oil pressure,
  • poor fuel economy,
  • and a layer of sludge under the hood.

It is essential to replace the oil cooler if you see these symptoms. Otherwise, it may lead to severe damage and reduce the lifespan of your vehicle.

Oil Leaks

A lousy oil cooler can cause an oil leak. O-rings become worn or brittle, which doesn’t seal the lines tightly. Regular car inspections can spot these leaks. Smoke from under the hood or around the exhaust pipe means oil isn’t dispersing evenly. Pressure in the cooling system can indicate a weak seal caused by a faulty oil cooler. Overheating and breakdowns can occur if these issues go unchecked.

It’s essential to act quickly to avoid permanent damage:

  • Check for oil leaks.
  • Check for smoke from the hood or exhaust pipe.
  • Check for pressure in the cooling system.
  • Check for overheating and breakdowns.

Poor Performance

Bad engine performance can indicate that the oil cooler is not working correctly. It cannot regulate the temperature of the engine. This might mean the engine runs too hot or too cold. Too hot can lead to power loss and high combustion temperatures. Too hard can cause a fuel efficiency drop and incorrect air/fuel ratios. If either state continues, it can damage car parts.

Unusual Noises

An oil cooler gone wrong may cause an unusual noise from the engine – like grinding or rattling that gets louder when the car accelerates. Vibrations may also be felt due to debris and worn parts.

Hot readings on the dashboard could mean a coolant leak from the oil cooler, causing excessive engine heat.

Decreased performance and low fuel efficiency could also be signs of a bad oil cooler. It can lead to reduced power output, sluggish response time, and torque.

It’s always good to check your car health often. If you hear any strange noises from the hood, investigate the issue immediately – it could be the oil cooler.

Excessive Smoke

When the oil cooler is not working, it can cause smoke to come out of the exhaust pipe or even appear as black-gray clouds when you accelerate. If your car emits more smoke than usual, this could indicate problems with the oil cooler. Also, when you start your vehicle, you may see more smoke due to the oil’s temperature changing quickly.

If you see large quantities of white, light blue, or grey smoke coming from the tailpipe, this is an issue with the oil cooler system. Even after the engine runs for a few minutes, some white-gray smoke may still be visible from the exhaust pipe. Too much engine heat and not enough cooling of the engine oil can cause motor oils and other lubricants to deteriorate quickly. If not fixed, this could lead to more damage and more significant repair costs.


Thus, a few fundamental indications of a malfunctioning oil cooler should be watched. If your oil temperature rises quickly or your vehicle guzzles more oil than usual, this may signify the cooler is failing. Also, look for any seepage around the cooler or additional noise from the cooling system.

Lastly, if you detect any of these symptoms near the oil cooler, it is crucial to immediately have it replaced to prevent further harm to your engine and other parts of your car.

Frequently Asked Questions

What are the signs of a bad oil cooler?

Signs of a bad oil cooler include a sudden drop in oil pressure, engine overheating, and an oil leak.

What causes an oil cooler to fail?

An oil cooler can fail due to debris or sediment buildup from the oil, a faulty gasket, or a broken internal component.

How can I tell if my oil cooler is terrible?

You can tell if your oil cooler is terrible if you experience any of the symptoms mentioned above or notice a decrease in engine performance.