Owner's Problem Description
The owner reports that their 1998 Saturn SL2 will not start. They discovered oil in the number 1 spark plug hole, which could indicate a valve cover gasket failure. Previous discussions revealed that similar issues were resolved by changing the valve cover gaskets and spark plugs. The owner is currently cleaning out the oil and is considering whether they can perform the repair at home or if it should be taken to a professional. They are also inquiring about the cost range for repairs.
Professional Technical Analysis
The 1998 Saturn SL2 is equipped with a 1.9L DOHC engine and typically experiences issues related to valve cover gasket failure, particularly in high-mileage vehicles (often over 150,000 miles). The reported symptom of oil accumulation in the spark plug well suggests a compromised gasket, leading to possible misfires or starting issues due to oil fouling the spark plug. This is supported by the owner's observation of the oil smell and prior repairs by others experiencing similar issues. The interconnection of the ignition system and oil intrusion could cause erratic spark performance and prevent the engine from starting. If the valve cover gasket fails, it can lead to oil leaking into the spark plug wells, which in turn disrupts ignition and affects the engine's ability to start. The current vehicle condition is critical as continued attempts to start the engine with oil in the plug hole could result in further damage. Based on experience, it's crucial to address the valve cover gasket issue promptly to prevent additional complications such as oil contamination in the ignition system. The engine must be properly assessed for overheating or other underlying problems that may have contributed to the gasket failure. Safety concerns include potential electrical hazards when dealing with spark plugs and ignition components, and the need for proper cleaning to prevent oil-related misfires.
Possible Causes
Most common causes (ordered by frequency):
- Valve Cover Gasket Failure: The valve cover gasket is a critical seal that prevents oil from leaking into the spark plug wells. When this gasket fails, oil can seep into the spark plug hole, resulting in fouled plugs and potential no-start conditions. Commonly, this failure occurs in vehicles over 100,000 miles due to wear and exposure to engine heat. Replacing the valve cover gasket (OEM part number 21005225) is necessary, and torque specifications for the bolts are typically 89 lb-in in a crisscross pattern. - Oil found in the number 1 spark plug hole, burning oil smell, previous repair history indicating similar issues resolved by gasket replacement.
- Fouled Spark Plugs: If oil seeps into the spark plug wells, the spark plugs can become fouled, leading to poor ignition performance or no-start conditions. Spark plugs should be inspected and replaced as necessary. The correct spark plug for the Saturn SL2 is ACDelco 41-101, and they should be gapped to 0.060 inches for optimal performance. - Presence of oil on the spark plugs, signs of misfire during previous attempts to start the engine, inspection shows wet tips on plugs.
- Ignition System Issues: Other components within the ignition system, such as ignition coils or wires, may also contribute to a no-start condition if they are damaged or worn. Checking the resistance of the ignition wires (should be around 5,000-10,000 ohms) and the ignition coil output (should be around 12V) can help identify faults. - Testing shows resistance in ignition wires exceeds specifications, intermittent spark observed during cranking.
Diagnostic Steps
Professional Diagnosis Process
Follow these systematic steps to accurately diagnose the issue. Each step builds on the previous one to ensure accurate diagnosis.
- STEP 1 - Initial Inspection: Start with a visual inspection of the engine, particularly around the valve cover and spark plug areas. Look for any signs of oil leakage or damage. Remove the spark plugs to check for oil presence and fouling. Use a torque wrench to ensure proper reinstallation of any components removed. Safety precautions include ensuring the engine is cool before inspection and avoiding contact with hot components.
- STEP 2 - OBD-II Scan: Use a professional OBD-II scanner or GeekOBD APP to check for any fault codes related to the ignition system or engine performance. Look for codes that may indicate a misfire or other ignition issues. Ensure to record freeze frame data for further analysis.
- STEP 3 - Fuel Pressure Check: Verify the fuel pressure using a fuel pressure gauge. The fuel pressure for the Saturn SL2 should be around 35-45 PSI at the fuel rail. If the pressure is low, it could indicate a fuel pump issue that may also affect starting.
- STEP 4 - Component Testing: Test the ignition coil and wires using a multimeter. The resistance for the ignition wires should be within 5,000-10,000 ohms, and the ignition coil should provide around 12V output when tested. Replace any faulty components as needed.
