Subaru engines, particularly the EJ series, are loved by enthusiasts for their unique boxer configuration and turbocharged performance. However, these engines have earned a reputation for reliability issues, especially when it comes to rod knock, head gaskets, piston ring, and bearing failures. In this article, we’ll delve into these problems, explore their causes, and discuss key upgrades to enhance your engine’s longevity and reliability.
What Causes These Failures in Subaru Engines?
Rod knock, Piston ring/ringland and bearing failures are often the result of insufficient lubrication, high operating temperatures, or prolonged stress on engine components. Key factors include:
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Oil Starvation: Subaru’s factory oiling system can sometimes struggle to keep up with the demands of high-performance driving.
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Heat Management Issues: The boxer engine layout can lead to uneven cooling, particularly around cylinder 4.
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Poor Maintenance: Neglecting regular oil changes, excessive oil leaks (Oil Pressure Sender leak as the most common cause) or using low-quality oil can exacerbate wear and tear on bearings.
Essential Upgrades to Improve Subaru Engine Reliability
To address these issues and prolong the life of your Subaru engine, consider the following reliability upgrades:
1. Killer B Oiling System
The Killer B oiling system is a must-have for any Subaru enthusiast looking to tackle oil starvation issues. This system includes:
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High-Performance Oil Pickup: Prevents cracking and ensures consistent oil delivery under high-stress conditions.
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Baffled Oil Pan: Reduces oil slosh during spirited driving or track use.
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Oil Baffle Windage Tray: Helps to maintain stable oil flow and reduce aeration.
2. Cylinder 4 Cooling Mod
Cylinder 4 is notorious for running hotter than the other cylinders due to its location in the engine block. The cylinder 4 cooling mod redirects coolant flow to this critical area, reducing the risk of overheating and premature wear.
3. High-Quality Oil and Proper Weight
Using the right oil is crucial for preventing rod knock and bearing failures. Always opt for:
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High-Quality Synthetic Oil: Brands like Motul, AMSOIL, or Rotella T6 are highly recommended.
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Heavier Oil Weight for Summer/Spirited Driving: Consider using 5W-40 or 10W-40 in warmer climates or during aggressive driving to maintain better film strength.
4. Air Oil Separator (AOS)
An air oil separator prevents oil vapor from re-entering the intake system, reducing carbon buildup on intake valves and improving overall engine efficiency. Brands like IAG Performance and Crawford offer excellent options.
5. 11mm Oil Pump
Upgrading to an 11mm oil pump increases oil flow and pressure, ensuring adequate lubrication for high-performance applications.
6. MLS Head Gasket and ARP Head Studs
The use of MLS head gaskets and ARP Head Studs ensures a stronger overall material and composition for the head gaskets in addition to the increased clamping force of the head studs ensures that the head gaskets can resist any added pressures from increased boost and mitigate against these failures
7. Proper Engine Tune
A professional engine tune is critical for optimizing air-fuel ratios, ignition timing, and boost levels. An improper tune can lead to detonation, excessive heat, and undue stress on engine components.
Additional Reliability Upgrades
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Oil Cooler: Helps maintain stable oil temperatures during demanding conditions.
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Turbo Heat Shield: Protects surrounding components from excess heat.
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Fuel System Upgrades: High-flow injectors and a fuel pump ensure adequate fuel delivery, reducing lean conditions.
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Regular Maintenance: Consistently check for oil leaks, replace worn gaskets, and stick to a strict maintenance schedule.
Preventative Maintenance Tips
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Monitor Oil Levels: Regularly check and top off your oil to prevent starvation.
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Use a Quality Oil Filter: Stick with OEM or high-quality aftermarket filters for optimal oil flow.
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Address Leaks Promptly: Oil leaks can quickly lead to low oil levels and engine damage.
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Invest in Gauges: Install oil pressure, oil temperature, and coolant temperature gauges to monitor critical engine parameters.
Conclusion
While Subaru engines may have a history of rod knock and bearing failures, proper maintenance and targeted upgrades can significantly enhance their reliability. By investing in components like the Killer B oiling system, cylinder 4 cooling mod, and air oil separator, you can protect your engine from common pitfalls. Remember, consistent maintenance, high-quality oil, and a proper tune are the foundation of a reliable Subaru engine.
At SSS JDM, we’re passionate about helping enthusiasts get the most out of their vehicles. Browse our selection of Subaru performance parts and reliability upgrades to keep your boxer engine running strong for years to come.