Some Subaru models have a 2.5L turbo boxer engine. However, in all models, the 2.5L turbo engine seems to have reliability issues that hinder the usability of the car. Some of the most common issues with the 2.5L turbo engine in Subaru vehicles are below. However, keep in mind that some of the issues vary by the model of Subaru and the exact engine that is used.

What are the most common issues with the Subaru 2.5 turbo engine?

The Subaru 2.5  turbo engine has a long list of common issues, including:

  • Fragile head gaskets
  • Oil and coolant mixing together
  • Rod bearings breaking
  • Oil leaks and filter clogs
  • Oil starvation
  • Valve cover leaks
  • Broken piston rings
  • Misfiring
  • Coolant leaks

For a full breakdown of these most common problems with this Subaru engine, keep reading!

1. Head Gasket

The head gaskets of Subarus with a 2.5L turbo engine are notorious for having head gaskets that break after 10,000 miles or 10 years of use. 

It is actually the #1 issue that owners have to fix. Unfortunately, it is extremely expensive to replace head gaskets, especially if the Subaru is older and the parts necessary to make the repair are hard to find. 

The head gaskets of 2.5L Turbo engine Subarus break so often because they are made of cheap materials, especially older Subarus. 

These head gaskets are made out of composites and are extremely thin, so it is no wonder they break and cause issues within Subarus.

2. Oil and Coolant Mixing Together

Because of the defective head gasket, oil and coolant often mix together in Subarus with 2.5L turbo engines. When oil and coolant mix together, a sludge is created.

That sludge means the coolant and oil can’t do their jobs, and it can sometimes get stuck in the engine and hinder its performance.

The sludge means that the oil can’t lubricate the engine, and the coolant can’t cool it down. This causes the engine to work harder than needed to function, engine parts to break or wear out prematurely, and can potentially cause it to overheat because there isn’t enough coolant.

3. Rod Bearings Breaking

The rod bearings in Subaru 2.5L turbo engines often break, especially those in an EJ255 turbo engine. The breaks are typically caused by a lack of oil.

When rod bearings break in a Subaru 2.5L turbo engine, they start to knock against the engine’s cylinder walls. 

If the issue is not fixed immediately, the rod bearings could make a hole in the engine block or cause the motor to seize. This will prevent your engine from working and cause more damage than there was initially.

If your Subaru’s rod bearings are broken, you will hear knocking in your engine, see metal shavings in the oil when you or a car repair tech drains it, and your car will lose oil pressure. Take your car to a car repair shop as soon as possible if you notice any of these issues.

Subaru 2.5 Turbo Engine Problems 1 Subaru 2.5 Turbo Engine Problems: 9 Common Issues

4. Oil Leaks and Filter Clogs

Subarus with 2.5L turbocharged engines have extremely small oil filters, which causes them to get clogged easily. 

Once the filters are clogged, oil won’t go through them and will just bypass the filter, which means gross and dirty oil will run through your Subaru’s engine. If it has old or dirty oil running through it, it won’t work as well as it should.

The small filters can also cause oil to leak. If oil leaks into parts of the engine that it’s not supposed to be in, it will damage your car’s engine. Oil leaks can also make your car lose oil.

5. Lack of Oil (Oil Starvation)

A lack of oil, otherwise known as oil starvation, is a common issue that is found in Subarus with a 2.5L turbo engine. 

Oil starvation is mostly caused by the small oil filter used in these engines, but it can also be caused by oil leaks if you don’t top off your car’s oil enough when it leaks to the exterior of your vehicle.

Because the oil filter is so small and gets clogged easily, not much oil gets through the filter, even when it bypasses the filter. This means your car’s engine won’t get enough oil, and parts will wear out faster or break. 

6. Valve Cover Leaks

The valve covers on the head gaskets in Subarus with a 2.5L turbo engine rarely work after 10,000 miles or 10 years of use. As the car is used, they deteriorate and allow oil to leak. When the oil leaks, oil and coolant can mix together. 

These valves can easily be replaced, and you can have the replacement done ahead of time to avoid engine problems, but it is a hassle that most people don’t want to deal with.

If your Subaru’s valve covers need to be replaced, you will notice smoke coming from the engine, oil leaks, and the smell of burning oil. Take it to a car repair shop as soon as possible.

7. Broken Piston Rings

The piston rings in Subarus with a 2.5L turbo engine often break. These engines have 3 piston rings, and after the car is used for a while, the piston rings start to crack. 

If the cracked piston rings are not replaced, the pistons could start to break and the cylinder walls can be damaged. However, it is hard to find cracked piston rings, especially if the cracks are small.

If your car’s engine’s piston rings are cracked or broken, you will notice ticking or knocking coming from the engine, loss of compression, loss of power, and an excess of smoke coming from the exhaust.

8. Misfiring

Subaru 2.5L turbo engines are notorious for misfiring. Misfiring can be caused by many things, including boost leaks, vacuum leaks, broken or faulty piston ringlands, and tight valves. 

If your Subaru with a 2.5L turbo engine has black exhaust, doesn’t accelerate well, the sounds coming from the engine change, or idles roughly, it is likely misfiring. 

Take it to a car mechanic as soon as possible.

9. Coolant Leaks

Coolant leaks often are seen in Subarus that have a 2.5L turbocharged engine. It can be caused by many things, but it is often caused by a small hole in the tubing or a loss of connection to a valve. If you notice that your car is overheating, wait until the engine is cool and add coolant.

If the issue persists, take it to a nearby mechanic as soon as possible.

Overall, there are many issues with the 2.5L turbo engines used in Subarus. It may be best to consider a Subaru with a different engine or a turbo car made by a different car manufacturing company. 

However, that decision is entirely up to you.

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