7 Worrying Subaru EJ253 Engine Problems (2.5L Flat Four)

We already talked about the 2008-2013 Subaru Forester here on Lifeonfour, however, we never paid any attention to one of the most popular engines in the previous generation of the Forester. We’re talking about the 2.5L flat four boxer engine, dubbed the EJ253. This article will uncover all the common Subaru EJ253 engine problems.

Research is a word that most people hate because it means that they need to put some effort and actually spend some time researching. But that’s the wrong way to approach things, especially when it comes to buying a used car. Ten-year-old cars can have tons of problems, and you need to be aware of them if you want to live peacefully. And that’s why we are here to give you some help.

First, we are going to learn more about the Subaru EJ253 engine specs and see what numbers this engine makes. Then, we are going to cover the common Subaru EJ253 engine problems and learn what issues this Subaru has. Lastly, we will cover the applications of this engine. So, let’s get started.

Basic Subaru EJ253 Engine Specs

Now before we dive into the common Subaru EJ253 engine problems, let’s first cover some of the basic specs of the EJ253.

For those who don’t know, the EJ253 is a variation of the EJ25 engine. This is a flat-four boxer engine with 2.5L in displacement.

The EJ253 has replaced the previous EJ252 engine. This new engine included many improvements compared to its predecessor.

These improvements included reinforced casting around the main bearing journals and alterations to the cylinder liner shape. Also, this engine included a Tumble generator valve, to reduce the start-up emissions.

Also, engines produced from 2007 onward included Intelligent Active Valve Lift, also known as i-AVLS; this feature has provided a valve lift for one of the intake valves per cylinder.

On top of that, the MAP sensor that was regulating the intake volume was replaced by the MAF sensor. So, overall, the new EJ253 was a big refinement compared to its predecessor.

Nevertheless, here are the basic engine specs of the EJ253.

  • Configuration: Flat-Four
  • Displacement: 2.5L
  • Bore: 99.5 mm
  • Stroke: 79 mm
  • Block & Head Material: Aluminum
  • Head Design: SOHC
  • Fuel Injection: Port Injection
  • Horsepower: 162 – 175 hp
  • Torque: 167 – 169 lb-ft (226 – 229 N-m)

Common Subaru EJ253 Engine Problems

Now let’s list the most common problems with the EJ253 engine

  • Oil Pump & Cam Seal Leaks
  • Idler Pulley & Tensioner Failure
  • Head Gasket Failures
  • High Oil Consumption
  • Rod Bearing Failure
  • Alternator Failures
  • Fuel Pump Failures

Now that we covered the main problems with this engine, we can move on and further elaborate on these issues.

We feel the need to further explain when and how these problems happen. This way, you will have a good perspective on how serious these problems are and how you can detect them on time. So, let’s get started and elaborate on each of these issues in detail.

1. Oil Pump Seals and camshaft Seal Leaks

The most common problem with this engine is oil leaks that can come from various places. But the most common ones are the oil pump seals, the camshaft and crankshaft seals.

These are rubber O-rings that over a long time and a lot of miles are starting to get hard, and they simply break.

So, it is a good idea to replace them if the engine has higher mileage because if you don’t replace them, the engine will lose oil if they start to leak.

That’s why we would recommend that you do so. Since these issues can appear on the highway, you can start losing a serious amount of oil. So, when you get to the destination, the engine will suffer some serious engine loss.

That’s why we advise the replacement of these parts every couple of years in order to bulletproof the engine.

2. Idler Pulley & Tensioner Failure

Another very common problem on these engines is the issue with idler pulleys and tensioners. Both for the timing belt and the drive belt.

This engine uses a timing belt and this belt has an idler pulley and a tensioner. And this is the same case with the drive belt.

What happens on these engines is that these components can fail and cause problems. There can be squeaks and noises when the idler pulley fails.

Or there can be a failure if the tensioner relieves some of the tension. That’s why we recommend that you monitor the condition of the belts and whether they are making noises.

The timing belt is the bigger concern in this case. If this belt fails, you will have permanent engine damage. Since the valves and pistons will collide with each other.

3. Head Gasket Failures

Head gasket failures are very common on these engines. Especially engines that were produced before 2003.

For those who don’t know, the head gasket is the gasket material placed between the cylinder head and the deck of the block.

This gasket has the purpose of keeping a seal between the two components. And if a head gasket fails, there will be coolant leaks, coolant mixing with oil, and overheating.

The most problematic are the engines before 2003 because these engines were using some cheap head gaskets that didn’t hold particularly well.

So, Subaru replaced them with improved ones in the following years. But still, even with these head gaskets, Subaru engines simply love to overheat and fail these components.

This is why Subaru engines are such a pain to deal with in the first place. They are really unreliable because of these issues.

4. High Oil Consumption

High oil consumption is a common problem with these EJ25 engines by Subaru. They tend to drink a ton of oil.

Many owners are pretty unaware of this issue that has developed in their car and they drive like that.

In this case, the engine runs low on oil and this causes sludge and high engine wear. It will shave off a ton of miles of the lifespan of this engine.

That’s why we often advise that you always check the oil level and top off the oil if needed because you don’t want to leave the car running dry on oil.

Eventually, the engine will completely seize and you will need a brand-new engine.

5. Rod Bearing Failure

Another very common problem with the Subaru EJ253 engine is the rod bearing failure. So, what is a rod bearing, and why does it fail?

Well, this bearing is located between the rod and the piston. The rod bearing allows the piston to move freely.

And what happens to a lot of these engines is that they consume a ton of engine oil. So, whenever this happens, the rod bearings will fail.

The engine will spin a bearing and there will be a situation when the engine is knocking, also known as rod knock.

Whenever this happens, the way around will require a thorough engine rebuild or engine replacement.

Now let’s move on to the next Subaru EJ253 engine problems.

6. Alternator Failures

Alternator failures were also noted on the Subaru EJ253 engine. So, what is the alternator, and why does it fail?

The alternator in simple words is the generator that creates power. This generator creates electricity for the ignition and accessories to run.

And when these vehicles reach higher mileage, the alternator will fail and start to underperform. So, the battery can be constantly empty, the accessories can malfunction.

The way around this problem will be to either rebuild the alternator at a shop that is working with these components or replace it.

Replacing it can be somewhat expensive, and that’s why rebuilding it might be a better choice.

7. Fuel Pump Failures

And the last problem on our list is the problem with the fuel pump. We found a couple of reports on this component.

What happens is that the fuel pump that is located in the gas tank fails and this causes the engine to lose fuel supply.

Once this happens, the engine will shut off or not be able to start. The only way around this problem is to replace the fuel pump. Something that can be pretty expensive to do.

Which Models Have The Subaru EJ253 Engine?

  • Subaru Forester 2002 – 2008
  • Subaru Legacy/Outback 2001 – 2009
  • Subaru Baja 2003 – 2006
  • Subaru Forester 2003 – 2008


What Are Common Subaru EJ253 Engine Problems?

Common problems with this engine include high oil consumption that can lead to rod bearing failure and engine failure. Also, head gasket failures are quite common, fuel pump failures, alternator failures, and leaks from the camshaft and oil pump seals. Idler pulley and tensioner failures are also very common.

Is The Subaru EJ253 Engine Reliable?

Overall, this is a second-hand Subaru engine and we cannot say that will be reliable. These engines are very risky because they tend to fail very often and cause a lot of headaches to owners. This is why you should really inspect the vehicle and the engine thoroughly in order to be sure that it doesn’t have problems.

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