3 Common Subaru EZ36 3.6 Engine Problems

Subaru’s EZ36 engine offers a good balance of performance, reliability, and longevity. These engines can easily make it beyond the 200,000 mile mark without any significant issues. In fact, it really doesn’t have any major design flaws or inherent problems. It does however have a few components that are prone to failing as these engines age.

The EZ36’s timing chain tensioners and serpentine belts tend to wear down by the time you reach approx. 150,000 miles, and older engines are known to develop oil leaks in a few different places. Ultimately, all of these problems are more so general maintenance things verses true problems. But, they can lead to some bigger issues if not taken care of so we’re going to dig into each of these problems in-depth below.

Common EZ36 Engine Problems

• Oil leaks
• Belt tensioner
• Timing chain tensioner

1) Engine Oil Leaks

The Subaru EZ engines have a lot of potential locations for oil leaks to develop. It uses a lot of seals & gaskets which leaves a lot of room for leaks. All engines are prone to oil leaks as they accrue age and mileage. As such, oil leaks are common on older Subaru 3.6L engines.

With age gaskets and seals simply degrade. They become brittle, start cracking, and oil begins leaking. These leaks usually start slowly, but can become large leaks if not fixed in a timely manner. On the EZ36 engine there is a massive front timing chain cover. The engine also uses a 2-piece design for the oil pan gasket. Point is – there are a lot of large areas for oil to leak from.

Look for most oil leaks to develop after 8+ years and 100,000+ miles. Leaks can and do happen sooner, but it’s usually an age and mileage related issue. A few common areas for EZ36 oil leaks are the timing chain cover, valve cover, oil pan gaskets, and crank seals.

2) Serpentine Belt Tensioner

Some EJ series engines use two belts, but the design is different on the EZ36D engine. This engine uses a single serpentine belt to control all of the accessories. The single serpentine belt then uses one belt tensioner to keep tension on the belt. The serpentine belt tensioners are spring loaded to apply the proper amount of tensioner.

Over time, the spring within the tensioner wears down and can cause a few possible issues. For one, the spring may wear down and not be apply to apply enough pressure for proper belt tension. Another problem is that the EZ36 belt tensioner spring may “bounce” around under engine load. Then there’s the bearing on the pulley that can seize and cause problems.

Point is – there are a number of ways for the Subaru EZ36 serpentine belt tensioner to fail. Many issues are age related as the tensioner/pulley simply takes abuse with age and mileage. Belts and pulleys are standard maintenance on many cars, so it’s not a major issue in the grand scheme.

Belt Tensioner Symptoms

• Odd sounds from belt
• Accessory failures
• Overheating
• No start

Belt Replacement

Replacing the belt tensioner on the EZ36 is a fairly minor job. It’s usually a good idea to replace the whole tensioner and belt together, especially on high mileage Outback and Legacy models. The serpentine belt and tensioner kit will run about $100-150 in parts. Add in another $150-250 in labor and the job comes out in the $250-400 price range.

3) Timing Chain Tensioner Problems

Last up for EZ36 flat-6 engine problems is the timing chain tensioner. Fortunately, the Subaru timing chains are reliable and rarely have issues. The timing chain tensioner is a different story, though. This is also likely the least common problem on this engine.

Much like the serpentine belt tensioner the timing chain tensioner is responsible for keeping tension. Simply on the timing chain rather than the accessory belt. Anyways, this plastic tensioner has a tendency to wear down with age and mileage. Eventually, it cannot keep proper tension on the timing chain.

Timing chain tensioner issues are less common on the EZ36 when compared to the EZ30 engine. Problems can and do occur, though. It’s important to look for symptoms. The sooner the tensioner is caught the less likely the need to replace the timing chain or other parts.

Symptoms

• Rattling sounds
• Timing chain slack/marks
• Check engine light
• Poor engine operation

Tensioner Replacement

Again, issues with the Subaru EZ36 timing chain itself are rare. However, if the tensioner begins failing then timing chain replacement may be needed. Timing chain kits can run about $200-400 for parts alone. Labor can also be pretty involving, so another $300+ for labor is standard.

It makes for a fairly expensive repair when all is said and done. Fortunately, timing chain tensioner problems don’t happen often on the Subaru Outback or Legacy 3.6 flat-6 engine.

EZ36 Engine Reliability

Is the Subaru EZ36 flat-6 engine reliable? Yes, we believe the EZ36 earns average to above average marks for reliability. The engine doesn’t have any serious design flaws or issues.

The design of the EZ36 allows a lot of room for potential oil leaks. It’s standard stuff that all engines are prone to with age and mileage. However, the area of the 3.6 engine that requires sealing means leaks are even more likely. Otherwise, the serpentine belt tensioner is a common trouble area but it’s a minor issue in the grand scheme. Last are the timing chain tensioners, but they’re a pretty uncommon issue.

Of course, a lot of Subaru EZ36 reliability comes down to maintenance. Use high quality oils, change fluids on time, and fix problems if and when they happen. It’s all basic stuff that should be done with any engine. Do all of this and chances are it will live a long and reliable life. With proper maintenance the engine shouldn’t have any issues surviving beyond 200,000 miles.