Parts for your 2020 Subaru Legacy

The Role and Maintenance of the PCV Valve on the 2020 Subaru Legacy

The 2020 Subaru Legacy does not actually use a traditional Positive Crankcase Ventilation (PCV) valve like some other vehicles. Instead, Subaru employs a different system design for managing crankcase gases, which is why you won't find a standalone PCV valve under the bonnet of this particular model. Understanding why this system differs and what that means for maintenance is helpful for any Legacy owner keen on keeping their car running smoothly.

So, why no PCV valve on the 2020 Subaru Legacy? Subaru has engineered its engines to have an integrated PCV system that uses hoses and passages rather than a single valve component. This is partly due to Subaru's horizontally opposed 'Boxer' engine layout, which has a unique crankcase ventilation setup. The traditional PCV valve, commonly found in inline or V-type engines, helps redirect gases that escape from the combustion process back into the intake manifold to be burnt off, reducing emissions and preventing pressure build-up inside the engine. But in Subaru's boxer engine, this ventilation is managed more through specially routed hoses and one-way check valves rather than a single PCV valve.

This design works well with the flat layout of the engine and helps to optimise the flow of gases through the engine's crankcase and intake, while reducing oil contamination and maintaining engine efficiency. What it means for the 2020 Subaru Legacy owner is that the specific component called a PCV valve isn't something to inspect or replace during routine servicing, as it just isn't part of this model's design.

Even without a traditional PCV valve, managing crankcase ventilation is still crucial on the Legacy. Subaru's design means that their maintenance routines focus on checking and replacing the related hoses, pipes, and seals in the ventilation system. Over time, these hoses can become hardened, cracked, or blocked with oil and carbon deposits, which can cause performance issues or even damage if left unchecked. So, rather than swapping out a PCV valve, technicians will inspect the entire ventilation circuit as part of regular service intervals.

With that context, let's dive into what owners should know about the equivalent system in their Legacy and the practical side of servicing it.

• Purpose of the PCV System - Even though the 2020 Subaru Legacy doesn't have a traditional valve, the crankcase ventilation system's job remains the same as in any internal combustion engine. It's there to relieve pressure inside the crankcase, prevent the build-up of moisture and harmful gases, and redirect vapours back to the engine's intake side so they can be burned off instead of released into the atmosphere. This helps maintain engine health and keeps emissions down.
• Signs of a Problem - Owners might experience rough idling, oil leaks around the engine, excessive oil consumption, or even a burning smell if the ventilation hoses or seals fail or block up. Because there's no single PCV valve to replace, problems tend to be related to hoses developing leaks or blockages.
• Routine Checks - During servicing, mechanics should check the condition of all ventilation hoses connected to the crankcase and intake manifold. This includes testing for cracks, brittleness, or oil contamination. Keeping these hoses clear ensures the ventilation system functions properly.
• Replacement Advice - If any gasket or hose shows signs of wear, it should be replaced with genuine Subaru parts to ensure a proper fit and performance. Using aftermarket hoses might save a few bucks but can lead to premature failures due to variations in material quality or fit.

Many owners might wonder why Subaru has chosen to avoid a traditional PCV valve on this engine design. The main reason revolves around the boxer engine's layout, which presents unique challenges when routing ventilation gases. Standard PCV valves can sometimes become clogged or sticky due to oil sludging, affecting performance. Subaru's system uses a combination of check valves and specific hose routing, which can be less prone to these issues and support their low-emission and long-lasting engine goals.

From a maintenance standpoint, while there's no need to hunt down a PCV valve as a separate component, Legacy owners should not neglect the ventilation system. A blocked or leaking crankcase ventilation system can cause increased internal crankcase pressure. This can lead to oil leaks at seals and gaskets, potential engine performance issues, and increased emissions. Regular inspections during scheduled servicing help find minor hose damage before it turns into a bigger, costlier problem.

Furthermore, engine oil changes and filter replacements are also key maintenance items that work hand-in-hand with a healthy crankcase ventilation system. Clean oil reduces the chances of vapour contamination and sludge formation in the ventilation hoses, which helps the system operate efficiently.

In short, while there is no traditional PCV valve to replace, the crankcase ventilation system on the 2020 Subaru Legacy remains a vital part of the engine's health and performance. Keeping hoses and related components in good order is essential. Legacy owners are encouraged to discuss any signs of crankcase ventilation issues with their service technician to help catch and fix these things early on.

Knowing this also means owners can feel confident during servicing that they're getting the right care for their vehicle. Subaru's approach to crankcase ventilation on the Legacy demonstrates a thoughtful design balancing simplicity, reliability, and environmental friendliness. So even without a PCV valve, the system is getting the job done.