How to Rebuild a Subaru Engine: A Comprehensive Guide for DIY Car Enthusiasts and Mechanics

Subaru engines are known for their reliability and performance, but like any other machine, they require maintenance and occasional repairs. If you’re a car enthusiast or mechanic who wants to learn the ins and outs of engine rebuilding, this guide will walk you through the process of rebuilding a Subaru engine step-by-step. We’ll cover everything from tools and parts required to diagnosing engine problems and preventive measures.


This article targets car enthusiasts, mechanics, and DIY car enthusiasts who want to learn how to rebuild a Subaru engine. From novice to intermediate level knowledge, we aim to cater to all levels of knowledge.

Subaru Engine 101

Before diving into the process of rebuilding a Subaru engine, it’s essential to understand the basics of how it works. Subaru engines are four-stroke internal combustion engines that use horizontally opposed pistons. The cylinders are arranged in a flat-four configuration, which gives the engine a lower center of gravity and better handling. Subaru engines also have a reputation for being durable and long-lasting.

Tools and Parts Required

To rebuild a Subaru engine, you’ll need the following tools:

  • Socket set
  • Combination wrench set
  • Engine hoist
  • Engine stand
  • Torque wrench
  • Piston ring compressor
  • Connecting rod bearing scraper
  • Feeler gauge
  • Timing light

You’ll also need the following parts:

  • Engine gaskets
  • Piston rings
  • Bearings
  • Timing belt
  • Oil pump
  • Water pump
  • Head gaskets
  • Camshaft seals

Step-by-Step Guide for Rebuilding a Subaru Engine

Now that you have the tools and parts required let’s walk through the steps to rebuild a Subaru engine:

  1. Remove the engine from the car and disassemble it.
  2. Inspect and diagnose the engine for any problems. (It’s recommended to have a specialized mechanic to do this)
  3. Clean all engine parts thoroughly.
  4. Inspect the connecting rods and crankshaft for any damage and replace if necessary.
  5. Install new piston rings and pistons into the engine block.
  6. Install new rod bearings and main bearings.
  7. Install the oil pump and water pump in place.
  8. Install the timing belt and timing components.
  9. Reinstall the cylinder heads and torque down to specifications.
  10. Install the new camshaft seals.
  11. Reinstall all other components, including the intake and exhaust manifolds.
  12. Install a new engine gasket kit to seal the engine back together.
  13. Reconnect all hoses, wiring, and other connections.
  14. Reinstall the engine back into the car.
See also  How to Connect the Black Yellow Wire on Your Subaru p127 Deck for Perfect Stereo Installation

Preventive Measures

After successfully rebuilding your Subaru engine, it’s essential to take proper care of it to avoid future engine problems. Here are preventive measures that can help:

  • Regularly change the oil and oil filter.
  • Replace the timing belt every 100,000 miles.
  • Check and replace the air filter regularly.
  • Use a high-quality fuel injector cleaner.
  • Inspect and replace spark plugs as needed.
  • Keep an eye on the temperature gauge and address any issues promptly.

Engine Problems and Diagnosis

Despite the preventive measures, engine problems can still happen. Here are some common problems that you may encounter with your Subaru engine, and how to diagnose them:

  • Overheating: Check the coolant level, radiator, and thermostat.
  • Misfires: Check the spark plugs and ignition coils.
  • Low oil pressure: Check the oil level and oil pump.
  • Engine noise: Check for loose or worn components such as timing components, rods, or bearings.


Q: Can I rebuild a Subaru engine myself?
A: Yes, if you have the necessary tools, parts, and knowledge, you can rebuild a Subaru engine yourself. However, it’s recommended that you consult with a specialized mechanic or experienced hobbyist before attempting to rebuild an engine.

Q: How long does it take to rebuild a Subaru engine?
A: The time it takes to rebuild a Subaru engine varies depending on the extent of the damage, the availability of parts, and the skill level of the person doing the rebuilding. Plan on one to two weeks for the entire process.

Q: Is it worth it to rebuild a Subaru engine?
A: Yes, rebuilding a Subaru engine can be worth the time and investment, especially if the car has sentimental value or unique features that would be challenging to replace.

See also  Can Subaru Make a Key from the VIN?


Rebuilding a Subaru engine is an involved process that requires knowledge and experience. By following this guide, you’re on the path to giving your engine new life. Remember to take preventive measures and address any problems promptly to keep your engine running smoothly for years to come. Happy rebuilding!

Avatar photo

Alton Brobst

As a longtime Subaru enthusiast, Alton brings a wealth of knowledge and experience to our blog. From his early days of tinkering with engines to his current role as a certified Subaru technician, Alton has seen it all when it comes to Subarus. When he's not working on cars, he enjoys hiking and exploring the great outdoors.

Recommended Articles