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Time to read 9 min
As we know, every dedicated Subaru enthusiast undoubtedly has their preferred platform. If you have been around our community for a substantial length of time, you know these faithful individuals will accept the common frustrations an owner will feel because of flaws, issues, and/or specific problems that have become well-known over time. Whether you are a novice or an experienced enthusiast, you will quickly confirm that Subaru's 2.5 Turbo Engine is a popular performance choice within the community because of its impressive and efficient power output and innovative, compact design. In the world of modern performance, this obvious choice has attracted a good selection within the community, especially those searching for a vehicle that can provide success no matter what challenges are thrown its way. Although this favorite may “do no wrong” in the heart of the most dedicated enthusiast speaking about Subaru's 2.5 Turbo Engine like an angelic, faultless child may be both naive and careless. This engine, like any mechanism that was designed for high performance, cannot exist without experiencing some issues over time. Some alternative brand enthusiasts will report that historically, Subaru's naturally-aspirated engines behave much more reliably than their turbo-charged siblings. They claim that even though Subaru's turbo models are a fast and incredibly enjoyable experience behind the wheel, that reported issues like premature turbo failure, piston ring-land failure, melted exhaust valves, and other frustrations are not worth gambling with the investment of time, money, and energy it takes to keep them performing at peak levels.
The US was the first to receive a Turbocharged 2.5L in the 2004 STI. All previous examples were turbocharged 2.0L or 2.2L. The NA 2.5 was released in 94 as the "25D". The WRX was a 2.0L up until 2007, In 07 it changed over to a 2.5 known as the (255) which was the less powerful version of the STI's (257) sti engine. The STi was equipped with a 2.5t in 04 when it came to the US market (and only in the US market). In all other markets the STI was equipped with a 2.0L (Ej207) up until 2015. Short of some early STI models (Pre 01) that featured slightly different 2.0T Ej engines. Some variants of the Crosstrek do have a 2.5 but not an EJ, and not turbocharged. In the US market the Legacy GT, Outback XT, and Forester XT were equipped with a (255) in 04-05 with the STI counterparts. In reality, these were really STI engines (257) without the red intake manifold, Subaru was experimenting with the WRX (255) variant engine to be released in 07, which was detuned and some of the forged parts were removed before being put into production in order to save costs. These same models continued with the 255 up to 2015 ish when the line was changed over to the FA engine. In other markets the legacy chassis saw some weird engines, such as twin turbo Ej's and even a turbo diesel This inclusion has propelled all of these platforms with provenance and popularity attracting both drivers on the street, track and lovers of the overland lifestyle. Before making a lot of assumptions, focusing on what is fact and fiction, and what maintenance practices may align with common failures, we wanted to outline a handful of common issues that have affected owners of cars powered by Subaru's 2.5 Turbo Engine and, most importantly, identify the probability behind the problem.
Although it has been updated with several variants over the years, Subaru's 2.5 Turbo Engine has maintained a high level of praise for its reliability and performance, but one of its most common issues, Oil Starvation, has caused some criticism from both dedicated fan and skeptic outsider alike. Oil Starvation is defined as a condition when the engine is not supplied with its required amount of oil to keep it running both smoothly and efficiently. This lack of oil would result in overheating, but would first damage the bearings and other metal on metal components. The engine would be totally destroyed before it noticeably overheated. The excessive wear of these components will then affect the normal performance and functionality of the engine's mechanisms, which will cause the engine to fail. Any enthusiast will confirm the importance of maintaining an engine's oil levels, periodically checking these levels throughout the vehicle's timeline of performance, and maintaining a proper changing schedule to expel both dirty and/or old oil from the system to avoid problems. This is not always the case with every driver and how they have been schooled to maintain their platform. Subaru's 2.5 Turbo Engine requires a consistent and adequate supply of oil to ensure that it performs per its specification requirements and does not lead to serious damage or failure. Most importantly, even if the oil supply is at an adequate level, but has not been changed under an appropriate schedule, the oil could be dirty, filled with potential obstructions. This would most likely cause clogs in small oil galleys and more likely introduce debris and contaminants into the wear surfaces of the engine like on its rod bearings and camshafts. Proper maintenance, changing oil, replacing filters, and following a serious practice of checks will aid the enthusiast in keeping their Turbo Engine as healthy as possible. All Subaru enthusiasts who own platforms powered by the 2.5 Turbo Engine should also monitor oil pressure and ensure their oil is topped off.
We have learned that there are a number of factors regarding the vehicle's oil supply that must be kept in check to ensure an engine's proper operation. When lubrication flow is affected or altered it is guaranteed that a vehicle's moving parts will become seriously worn, damaged, or broken. Correcting an efficient flow of lubricants like engine oil is not the last step in the maintenance chain and it also works in concert with other operations to help the mechanical processes functioning as designed. Oil levels, pressure, and temperature work in union with other liquids to guarantee that a turbo engine will keep performing properly. Keeping a high performance engine running cool by controlling the temperatures of all its components is another critical aspect that should not be overlooked and that could contribute to issues with a Subaru 2.5 Turbo engine. Reaching an overheated state is never a good situation for a vehicle to be caught on a daily drive under normal circumstances, but especially during more challenging scenarios. Coolant Leaks can quickly lead to an overheated state and in turn cause serious damage and even catastrophic failure to a 2.5 Turbo engine. One of the most common reasons for a vehicle to leak coolant is a damaged or faulty radiator cap, ruptured hose, or other fractured component in line with the coolant system's flow. A failure at any one of these points can result in interrupted or stoppage of coolant flow, a rapid rise in engine temperature, and a damaging failure if not addressed immediately. Coolant leaks should never be ignored or left unchecked. Remember, the engine depends on its coolant to play a critical role by absorbing excess heat, circulating it through the vehicle's entire system to regulate the engine's overall temperature. Even a small leak can alter the proper measurement of coolant required by design to avoid excessive engine heat leading to warped components, immediate failures or extensive, long term issues.
Again, as we have mentioned, both experienced and novice enthusiasts realize that problems can appear even if they maintain a perfect maintenance plan, follow each directive by the book, and never sway from good habits and care practices to protect their investments. An automobile is constructed from metals, plastics, and other materials that are affected by wear and tear that is not always caused by an abnormal or dysfunctional action. Sometimes parts just break, connections disengage, and operations stop their designed functions. But, as we have stressed, it is important to analyze that categorizations of common failures are most due to avoided practices and strict attention to details when owning and driving a Subaru vehicle, especially one equipped with a 2.5 Turbo engine. As we move forward to examine one of the last few most common problems aligned with Subaru's 2.5 Turbo engine, we will come upon an issue that is most daunting when confronted, the Blown Head Gasket. This is a critical component whose failure or degree of damage can create a domino effect of issues that combine both oil leakage, coolant leakage, and overheating in the same, most immediate breath a driver could imagine. The head gasket creates a seal between the engine block and the cylinder head to effectively keep both engine oil and coolant contained, and flowing easily and freely between both components. As we have mentioned, and what is important to emphasize, a head gasket failure can lead to monumental issues for the vehicle which include a decrease or stop in performance, leakage of oil, leakage of engine coolant, and immediate overheating, which as we've learned can escalate into more catastrophic damage or engine failure. Much like the other issues we have discussed, due diligence, constant attention and monitoring of your engine's proper function, and keeping a watchful eye for specific symptoms can be the difference between catching a future problem with some preventative maintenance, dealing with a costly repair or replacement, or a possible life threatening accident. Common symptoms include a noticeable oil leak at the head, increased engine temperature, or a dramatic amount of white smoke coming from the tailpipe. No matter which is noticed, it is important to address and diagnose these symptoms immediately.
As Subaru enthusiasts we are dedicated to a brand that is, of course, far from flawless, but historically innovative and pioneering. If we pursue success and victory in our own automotive lifestyles, we follow the believe that it is always best to learn how to avoid issues and problems by first grasping Best Maintenance Practices, following care specifications to the letter, and focused on how to service your investment so it serves you efficiently and delivers performance consistently for all the years you spend behind the wheel. It can prove to be quite easy to avoid calamity when you keep your eyes on what is important and use your tools correctly and how they were designed. Keep in mind that all mechanical designs can fail but are less likely to when maintained properly. We have discussed three common issues that may affect Subaru's 2.5 Turbo engine to serve as a reference point for enthusiasts who want to remain aware of signposts that may lead to future trouble, but by no means let serve as a declaration of how non-existent problems will be if you own a Subaru. Keep aware, follow your service schedules, and always treat a performance vehicle and its engine with respect and it will pay you back ten fold with enjoyment and thrills.
Subimods continues to concentrate on providing aftermarket innovations and products that take the Subaru platform of your choice to new levels in the present and the future, no matter if you choose a more exciting, dynamic daily drive, a more exhilarating weekend on the track, or a more aggressive adventure overland and in the wild. Take a look at some options to help keep your Subaru vehicle in top condition, maintain the highest level of performance, and keep your engine running smoothly for many seasons to come. Scroll through some premiere product offerings for the Subimods Online Catalog and contact our team with any questions.
We would be very interested in your thoughts regarding this article and would encourage your feedback and comments regarding any issues or problems you have experienced with your Subaru's 2.5 Turbo engine.
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Bryon Turcotte - Managing Editor/Writer
Turcotte has worked as a writer, journalist, and digital content developer for 30 years. He began his career in music journalism in 1995 then worked for several years as both a staff writer, managing editor, and a freelancer for both regional and national music publications. Over the next three decades his contributions extended beyond the music industry as he served within the realms of higher education, science and technology, manufacturing, and finance. He has been serving as a content developer and writer on the Subimods Marketing team since August 2023.
