Checking & cleaning a PCV valve

Part 1. Preparation and safety

Objective

• Check and clean the PCV valve part of the emission control system.

Personal safety

Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:

• Work clothing - such as coveralls and steel-capped footwear
• Eye protection - such as safety glasses and face masks
• Ear protection - such as earmuffs and earplugs
• Hand protection - such as rubber gloves and barrier cream
• Respiratory equipment - such as face masks and valved respirators

If you are not certain what is appropriate or required, ask your supervisor.

Safety check

• Always make sure that you wear the appropriate personal protection equipment before starting the job. It is very easy to hurt yourself even when the most exhaustive protection measures are taken.
• Always make sure that your work area/environment is as safe as you can make it. Do not use damaged, broken or worn out workshop equipment.
• Always follow any manufacturer's personal safety instructions to prevent damage to the vehicle you are working on.
• Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.

Points to note

• When an engine is running, some of the air/fuel mixture and some of the exhaust gases can squeeze past the piston rings in the cylinder and leak into the crankcase. A method called "Positive Crankcase Ventilation" or PCV is commonly used to feed these gases back into the intake manifold with the rest of the fuel/air mixture.
• Most modern vehicles have a PCV valve, which should be checked periodically to make sure that it is not clogged with deposits from the exhaust waste. If it is not working properly, the engine may idle less smoothly, the fuel efficiency will drop, and the oil will become contaminated and less effective.

Part 2: Step-by-step instruction

1. Locate the PCV valve
   The PCV valve is usually located next to the valve cover of the engine, or in the intake manifold. If you cannot identify it quickly, check with the workshop manual.
2. Check PCV valve operation
   Switch on the ignition and start the engine. With the engine idling, pinch the hose attached to the PCV valve hard enough to shut off the supply of air through it. If the valve is working correctly, the idle speed should drop enough for you to be able to hear the change. Alternatively, remove the hose from the PCV valve attached to the valve cover, leaving the valve in place, and putting your finger over the opening of the hose, you should feel suction.
3. Clean PCV valve and hose
   Remove the hose and check that it is still pliable and not clogged with sludgy deposits. If the hose cannot be cleaned easily by blowing some air through it, then it should be replaced. Remove the PCV valve and inspect it for deposits. If it can be taken apart, then you can clean it with PCV solvent or lacquer thinners. If it cannot be dismantled but has restricted operation because of sludge, then replace it with a new one of the same type.