The Subaru WRX EJ205, engine bearings, and you.
Innovative Tuning’s head tuner Mike started working on Subarus with his 2002 model year WRX back in 2001. Spanning 2002-2005 model years in North America, we’ve been working on and tuning these 2 liter turbocharged cars for a long time know the engine well. It can be very reliable when treated with a great deal of care and respect, despite aggressive driving.
Every engine has its strengths and weaknesses. Over the years we’ve found the 2 liter engine’s common failure point is the bearings. This is not related to modifications/tuning. For example we’ve seen this happen on a stock car with as few as 30k miles and we’ve had 2 liter engines still running fine with performance upgrades at 180,000 miles.
Here are some things you can do to prolong engine bearing life:
Frequent oil changes (based on mileage and time)
Using good quality oil of the appropriate weight
Only loading engine heavily with oil up to temperature
Not overheating oil
Keeping oil at proper level
Don’t lug the engine down at low RPM which puts extreme stress on the rods and bearings
All it takes is letting an oil change go too long to hurt the bearings. The same goes for running on a turbo that’s worn out. This unfortunately may not show itself until a bearing spins hours, weeks, months or years later. Unless an engine is starved of oil and failure occurs all at once, engine bearing failure generally occurs over a period of time silently, culminating when a bearing or bearings spin. Sometimes this occurs while the driver is cruising along, other times it occurs while racing or on the dyno. Due to the age of this generation of car, an issue has often started while a previous owner had the car and the current owner doesn’t even know about it.
Hopefully you’ll never experience this issue and taking extra care of your engine will pay off. You’ll want to do everything you can to delay a rod bearing surprise.
Oil analysis and monitoring oil pressure are two ways of keeping an eye on bearing condition. If you spot a bearing issue early on, it can save you a great deal of money. Fixing this issue before bearings score heavily or a bearing spins can avoid cylinder head damage, damaging other block components and the turbo. Without oil analysis owners generally have no idea a bearing is about to fail. Oil analysis isn’t foolproof since bearing wear occurring between oil changes/analysis can occur, but it’s the best reasonably priced option to keep tabs on engine bearings. The oil used for analysis should be the oil you usually use, when it’s at the end of your usual oil change interval.
Because bearings that are worn often complete their demise when the engine is run at full boost and revved out near redline, this often happens during full throttle pulls. Failure can occur on the street, track or dyno. Dyno testing and tuning explores the full rev range and includes full boost operation so failure may occur during this process and is in no way related to the tuning being performed. Keep this in mind and be prepared to make repairs before considering modifying or tuning your two liter WRX.
Remember all engines have their weak points and the 2 liter WRX engine is not fragile. We bring the possibility of a bearing issue up because without mentioning it owners generally have no idea it’s coming until it happens. On another engine that has weak pistons you can often notice smoking, some loss of power or some other telltale sign before total failure occurs, allowing more time to plan the repair.