* Faulty PCV Valve: This is the most common cause. The PCV valve regulates crankcase pressure. A stuck-open or clogged PCV valve allows excessive crankcase pressure to build up, forcing oil vapor (and sometimes liquid oil) into the intake manifold.
* Clogged PCV Hose(s): The hoses connecting the PCV valve to the intake manifold and crankcase can become clogged with oil sludge or debris. This restricts airflow, increasing crankcase pressure and leading to oil entering the intake. Check all hoses for cracks, kinks, or blockages.
* Worn or Damaged Piston Rings: If the piston rings are worn, they allow excessive blow-by (combustion gases escaping past the pistons into the crankcase). This increases crankcase pressure significantly, pushing more oil into the intake. This is a more serious mechanical issue.
* Valve Cover Gasket Leak: A leak in the valve cover gasket can allow oil to seep into the valve cover and eventually find its way into the intake manifold, particularly if the PCV system is already compromised.
* Improperly seated or damaged oil filler cap: A poorly fitting cap can negatively affect the crankcase pressure regulation and contribute to excess oil build up.
* Breather Hose Issues: Similar to PCV hoses, breather hoses can also become clogged or damaged, hindering proper crankcase ventilation.
Troubleshooting Steps:
1. Inspect the PCV valve: Remove the PCV valve and check if it moves freely. If it's stuck or clogged, replace it.
2. Inspect the PCV hoses: Carefully examine all hoses for cracks, kinks, or blockages. Replace any damaged hoses.
3. Check the valve cover gasket: Look for any signs of oil leakage around the valve cover gasket. If there's a leak, replace the gasket.
4. Check the Oil Filler Cap: Ensure it is properly seated and free of debris or damage.
5. Consider engine compression test: If the problem persists after addressing the above, a compression test might reveal worn piston rings or other internal engine problems.
It's important to address the oil in the intake manifold promptly. Oil in the combustion chamber can lead to fouling of spark plugs, poor combustion, and potential engine damage. If you're not comfortable performing these checks yourself, it's best to take your Windstar to a qualified mechanic for diagnosis and repair.
