Engine: D5: Cleaning the PCV D5

[Joe Harding]

Sentinel parts will supply the PCV breather assy but you can prise the diaphragm cap off and see if the diaphragm is distorted or perforated. If it is you can just change that part in a fraction of the time and no need to fit new seals.

[davebb]

The D5 Does NOT HAVE A PCV SYSTEM,
Dave

[curiositea]

Originally Posted by davebb

The D5 Does NOT HAVE A PCV SYSTEM,
Dave

Vida, skandix and both my cars disagree.

[davebb]

Originally Posted by curiositea

Vida, skandix and both my cars disagree.

OK Does your Vida call it a PCV System on the D5, OR A BREATHER SYSTEM
Dave

[Kev0607]

I wasn't aware there was a PCV system on a diesel engine either...

[curiositea]

Originally Posted by davebb

OK Does your Vida call it a PCV System on the D5, OR A BREATHER SYSTEM
Dave

It is used interchangeably. That's because a Closed loop breather system (meaning the fumes are redirected back into the intake using the vacuum created by the turbo) is almost the same thing as a PCV. The only thing it's technically missing is a valve but die to how a turbodiesel works, this is not needed.

So yes, the D5 does indeed have a PCV system, it's just a little different from the gasoline/petrol versions.

You can even ask GPT4 if needed:

The distinction between a Closed Loop Breather System and a PCV (Positive Crankcase Ventilation) System, although they function similarly in many ways, lies in their design and the level of control they offer over the crankcase emissions.

### Closed Loop Breather System

A Closed Loop Breather System is essentially a simpler version of the PCV system, designed to manage the crankcase gases without the more complex components found in a typical PCV system. Here’s how it works:

- **Function**: This system captures blow-by gases (combustion gases that escape past the piston rings into the crankcase) and routes them back into the engine’s air intake system. This prevents these gases from being released into the environment directly and allows them to be burned off in the combustion process.

- **Components**: Typically, a Closed Loop Breather System includes a breather tube that connects the crankcase to the air intake, along with a filter or oil separator to prevent oil mist from entering the intake system. There is no regulating valve as seen in a PCV system; the flow of gases relies mostly on engine vacuum and natural pressure differences.

- **Emissions and Efficiency**: While this system helps reduce emissions and can improve engine efficiency by reducing the buildup of pressure in the crankcase, it does not offer the same level of control or effectiveness in managing all the blow-by gases, especially under varying engine loads and conditions.

### PCV System

The PCV system is a more advanced and controlled method of handling crankcase emissions, widely used in modern vehicles to meet strict environmental regulations. Here’s what differentiates it:

- **Function**: The PCV system also routes blow-by gases back into the engine's intake manifold, but it does so using a controlled valve that adjusts the flow based on engine conditions.

- **Components**: The key component in a PCV system is the PCV valve, which regulates the flow of gases from the crankcase to the intake manifold based on engine vacuum. This helps maintain optimal pressure in the crankcase and improves the efficiency of the gas recirculation, reducing emissions more effectively.

- **Emissions and Efficiency**: The PCV system is more efficient at reducing harmful emissions and improving engine performance. The regulated flow of gases ensures that the engine operates under optimal conditions, preventing issues like oil dilution and excessive oil consumption.

### Summary

In summary, while both systems aim to handle and recycle crankcase emissions, the PCV system offers a more sophisticated, efficient, and controlled approach, utilizing a valve to regulate gas flow according to engine conditions. In contrast, a Closed Loop Breather System provides a simpler solution by routing gases back to the intake without the use of a regulating valve, making it less effective in varying operational conditions but still improving upon the basic open breather system by reducing emissions.

But back to topic. I too am very interested in how and why the PCV/Breather on these D5s would stop working properly. Our V70 XC D5 2006 is loosing oil and the Dipstick has been pushed out while driving on the Autobahn multiple times (spraying oil everywhere yay). The diaphragm in the separator has already been swapped for a new one (and wasn't visibly broken). It's hard to find any real information on the system for the D5244T4 series (independent of what one calls it)