Owner's Problem Description
The owner reports an intermittent noise coming from the engine area of their 2005 Mitsubishi Eclipse. The noise occurs sporadically and does not happen every day. They had a timing belt and other related components replaced less than a month ago, but the noise started approximately 20,000 miles ago. A previous diagnostic indicated that the noise ceased when the external belt was removed, suggesting a possible issue with internal components. Suggestions have included potential problems with the lifters, tensioner, or insufficient oil reaching the top end.
Professional Technical Analysis
The 2005 Mitsubishi Eclipse, equipped with a 2.4L inline-4 engine and an automatic transmission, has reported an intermittent noise likely related to the engine's internal components. The vehicle has approximately 100,000 miles on it. The owner has experienced this noise sporadically over the last 20,000 miles, with recent repairs including the timing belt and tensioner replacement. The intermittent nature of the noise, along with the fact that it ceased when the main drive belt was removed, points towards potential internal engine issues such as camshaft, lifters, or followers. A thorough examination of the components is required, especially focusing on the oil delivery system to the top end. If the vehicle shows signs of poor lubrication, it may lead to premature wear or failure of these components. The noise may also be influenced by the tensioner, which while recently replaced, could exhibit failure patterns under certain conditions. Given the intermittent nature of the issue, it is crucial to monitor the engine during various operating conditions to identify the noise's specific triggers, as well as to check for any associated fault codes that may provide additional diagnostic insight.
Possible Causes
Most common causes (ordered by frequency):
- Internal Engine Noise: The noise may originate from internal components such as the lifters or camshaft followers. If the oil is not reaching these areas efficiently, it can lead to increased wear or failure. The vehicle's oil pressure should be checked, normal pressure should be around 25-60 PSI at idle, and higher during acceleration. If oil pressure is low, inspect the oil pump and the oil filter for clogs or inefficiencies. - Intermittent noise when engine is hot, noise ceases when external belt removed, possible stored codes related to oil pressure.
- Lifter Failure: The hydraulic lifters may not be functioning properly due to lack of oil flow, causing the noise. This is often a result of dirty oil or low oil levels. It's important to check the oil level and ensure that an oil change is performed with the correct viscosity, typically 5W-30 for this engine. - Noise correlating with engine temperature, potential for low oil levels or dirty oil, usual signs of lifter noise during cold starts.
- Tensioner Failure: Even though the tensioner was replaced, a defective or misaligned tensioner can cause abnormal noise. Inspect the tensioner for proper alignment and function. The tensioner should maintain a constant pressure, typically between 10-15 PSI when engaged. If it does not, it may need replacement. - Abnormal noise patterns when engine under load, clear signs of misalignment or wear on the tensioner.
- Oil Delivery Issues: If the oil delivery system is not functioning properly, this can lead to insufficient lubrication of the top end components. Inspect the oil pump and oil passages for blockages. The oil pump should generate at least 25 PSI at idle; if lower, further investigation is necessary. - Intermittent engine noise, particularly under load, and potential for low oil pressure readings during operation.
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 OBD-II Scan: Begin by using a professional OBD-II scanner or the GeekOBD APP to retrieve any stored fault codes. Focus on codes related to oil pressure, engine performance, and any intermittent codes that could provide insight into the noise. Pay attention to freeze frame data for conditions when the noise occurs.
- STEP 2 - Oil Pressure Testing: Check oil pressure using a mechanical gauge to confirm that it meets specifications, ideally at 25-60 PSI at idle and higher during acceleration. If pressure is low, inspect the oil pump and oil filter for clogs. Also, check the oil level and condition to ensure proper lubrication.
- STEP 3 - Inspect Tensioner and Lifters: Remove the timing cover to inspect the tensioner alignment and function. Confirm that the tensioner is properly torqued to specifications, typically around 80 lb-ft. Also, check the lifters for proper operation and signs of wear or blockage.
- STEP 4 - Road Test with Noise Monitoring: Conduct a controlled road test to replicate the noise while monitoring engine parameters with GeekOBD APP. Take note of conditions that trigger the noise and document any variations in oil pressure and other relevant parameters during the test.
