How to Complete the Subaru Short Block Replacement – Details Explained!

The Subaru short block Replacement manual is designed to make your job easier.

The instructions cover the information needed to remove, install, and align the new short block with the engine before rebalancing the crank bearings.

This document covers most of the models with 4-cylinder engines in their complete details.

Replacing the Subaru short block is possible only when you have the right details about the technical components of the engine.

Subaru Short Block Replacement: the Steps

This is useful when replacing a faulty engine part due to wear or when you just need help aligning pieces when putting it back together.

It’s also great for learning how to do maintenance on your own vehicle so you can save money in the future or fix an issue without having to take it in for repair over and over again.

Replacing the short block Subaru is a little bit complicated task so you need to focus on every step of the process.

Here are the major steps of Subaru short block engine replacement:

1. Removing the old engine

Removing the old engine is the first step. Remove all screws, nuts, bolts, and other parts that are restraining your vehicle.

You can perform this task by using a simple socket wrench and the other option is to do it in a manual way.

Remove all types of pipes that are attached to the radiator. If you have winter tires, be sure to remove all rubber hoses from them as well.

Take out the air cleaner assembly from under the hood or take off all hoses connected to it also, if it’s connected to your car radiator.

2. Remove the Old Belts

Remove all types of worn-out belts to replace them with new ones. You can detach them by your hand or by pliers.

Be careful not to damage the engine block, water pump, timing belt, and other parts of your vehicle because you could damage the whole engine block.

If your car doesn’t have a timing belt (most Subaru models don’t), then you won’t need to worry about that step after removing the hoses connected to it.

3. Remove all Hoses

You should also remove all hoses connected to the radiator, air conditioning system, and coolant reservoir.

All these hoses are usually connected by using clamps or special locking mechanisms, so it should be easy for you to remove them.

4. Taking out the Engine

Now it’s time to take out your engine.

If your car is equipped with an engine with an in-line six-cylinder configuration, you do it in two steps; otherwise, you only need to remove one side of the engine.

Please refer to your vehicle manual in order to know how to remove the engine.

If there are any parts of your car that you want someone else to do for you. So they will understand then take them along with you when you go to get the short block replaced.

Because some people may not know exactly how to fit it back into place or may forget some parts like water pump, timing belt and other things like that.

5. Removing the In-Line Six

If your car has an In-Line Six, then you need to remove the engine as two separate pieces. Take out the first side of the engine from under your hood.

Take it out slowly because there are usually transmission oil lines connected to it and you don’t want to damage them if you plan on using your old transmission again.

If you do plan on using it again, then disconnect all hoses connected to it so they won’t leak onto your new short block later on during the installation process.

6. Lifting the New Engine Out

After you take the first side of the engine out, it’s time to lift the new one in. Pay attention to how it is installed properly, so you will be able to put the timing belt back in place.

If your car isn’t equipped with an engine with an in-line six-cylinder configuration, then you should connect all transmission oil lines during this stage.

Because they are usually very easy to connect if they are not heavily damaged. Now it’s time to install your short block.

7. Install Short Block

Finally, after you disconnect all hoses connected to the new engine and put the old one back, take out the new engine assembly from your car.

Install it carefully into its original position.

Make sure that you don’t mix up the timing belt with any other rubber parts that are attached to it because your car needs them in order for your engine to run properly.

Now you can put back together everything that was removed before installing the new short block into place.

Now you can check if everything is in place and works properly before driving your vehicle again.

What is a Short Block Engine?

Short Block engines are also known as In-Line Six or inline 4 cylinder engines.

They are used in passenger cars and light trucks made by Subaru, Toyota, Nissan, Honda, BMW, Mitsubishi, and more.

The term “short block” refers to the engine block itself or the engine assembly.

You must be aware of the term short block engine if you are interested in Subaru short block replacement.

Subaru Short Block Engine Specifications

Either you are an experienced mechanic or car enthusiast; you must have knowledge about the technical specifications.

Engineering for every engine is different. Depending upon the model of the vehicle, there are always some variations.

The Subaru Short Block Engine is a modified version of the Mitsubishi Lancer engine with many improvements and new features, including:

  • A new cylinder head with improved airflow integrated under the top-side cam cover for more horsepower and torque
  • A revised intake manifold design including a larger diameter intake port to improve low/mid-rpm power
  • WS6 cylinder heads use hydraulic roller lifters which reduce noise levels while improving performance at high RPMs due to reduced friction losses.

In simple words, you can say that the short block is a complete engine assembly that contains the following major components:

  • Crankshaft/Connecting Rods
  • Piston/Cylinder Block Assembly
  • Cylinder Head Assembly
  • Valve Cover/Intake Manifold

These specifications are going to be pretty useful when you need to understand the real working of the engine.

Having a deep understanding of the different components also leads to better results while maintaining your car.

Short Block vs Long Block Subaru Engines: Face to Face Comparisons

The short block is also known as the engine block, the critical part.

In this guide, we have mainly covered all the important points that you need to know about replacing Subaru short block engine.

Short Block Engine

Short-block is composed of a crankshaft, connecting rods, pistons, main bearings, and other components.

The performance and reliability of the long block engine are usually better but some models only support the short block engine.

Long Block Engine

The long block includes all of these except for the cylinder heads. Long-block engines are so named because they have a longer number of cylinders than short blocks.

In an automobile engine, short blocks are mounted to a crankcase or head casting while long blocks sit in a frame that houses them all together.


In terms of pricing, a short block engine is cheaper than a long block engine. The exact cost of the engine is also associated with the make and model of the car.

You also need to remember that you need to buy some additional components with the short block engine for Subaru.

If you are thinking about engine replacement, consider the make and model of your car for precise results.


The warranty for the engine replacement is an important factor for the users. Short block engines come with limited-time and less warranty as compared to long block engines.

Usually, warranties only cover the parts that are included in the original purchase. With a short-block Subaru engine, you have to buy several additional components.

So, the warranty claim will not cover the additional parts.

Right Choice for your Vehicle

Although you might find the long block engine more reliable and powerful yet you need to consider all other aspects while making the purchase.

Not every vehicle supports all the engine blocks. For the short block Subaru, you may not be able to install a long block engine.

It is better to consult with a professional mechanic about making the purchase.

Common but Crucial FAQs for the Subaru Short Block Engines

While going through the engine replacement, you will encounter several issues and challenges. Here are some most common questions that relate to the topic of this guide.

You should read these FAQs for a better understanding of the subject.

1. What does Short Block Replaced Mean?

Short block replaced mean that engine is worn out to the maximum level and now it was impossible to use the old one.

Short block replacement is usually said as major servicing of the car. When a vehicle requires short block replacement, it is simply about car engine assembly replacement.

2. What is better between a short block and a long block engine?

Both short block and long block engines for Subaru have different capabilities and specifications.

In a nutshell, short block engines have a more powerful torque at lower RPMs while long block engines have a higher horsepower at higher RPMs.

In general, short engine blocks are often used in race cars because they’re light and offer high torque for acceleration from low speeds.

Longer engine blocks are usually found in sportier vehicles because they have a higher horsepower to weight ratio and can reach high rpm levels more easily.

It’s up to you which one you want, but keep in mind that your vehicle will be more powerful depending on the type of engine that you get installed.

3. When does a car need short block replacement?

Short block replacement is the process of removing the engine’s cylinder heads, repairing and installing new ones. It is also known as cylinder head overhaul or engine swap.

The most common cause of short block replacement is damage due to failed oil pump gears, camshaft wear, rocker arm wear, or piston ring problems.

A piston ring issue will happen when the ring slides out of place at one end without you even noticing.

This means your car may stop running completely with no warning signs whatsoever if it’s not caught in time.

The best way to prevent the problem is by checking your car for any unusual noises or vibrations which might indicate that something’s wrong with the engine before anything happens further down the line.

4. Are Subaru engines bad?

Subaru engines are not bad. Lifted Subaru is bad, but the engines themselves are very good for their intended use which is to move you from point A to point B in a reasonably safe manner.

If you have the following options then the Subaru engine is probably one of your best choices.

Because with these two choices, you’ll be able to get exactly what you want out of an engine without having any issues with it.

The thing about building a car with an engine is that it can be difficult because there are so many factors that have to align for everything else about the car to work together seamlessly.

5. Can you replace Subaru short block DIY?

It is possible only if you have the appropriate experience and tools. Without essential tools and resources, you may end up damaging your car.

It is better to seek professional assistance for such complicated replacement tasks.

6. Why does the Subaru engine need short block replacement?

A replacement Subaru engine is only needed in the event that the engine has completely failed.

That is vehicle-dependent, but in general, it can happen when higher mileage vehicles are taken to an extreme, such as when the driver excessively abuses the truck’s braking system.

7. Can you use any engine in your Subaru?

No, you cannot do so. Occasionally, short block replacement can also be needed when there are issues with other components in your Subaru engine.

Whenever there is a need for a new engine in your car, it will need to be replaced with an identical one or one which was specifically designed for your vehicle.


The whole guide was about making the replacement process easier and more understandable for you.

The exact steps for the replacement may vary depending upon the year of manufacturing. This manual will make your job a lot easier and more effective.

If you are stuck at any point, you can seek professional help from Subaru mechanics.