A worn camshaft can be a significant problem for older vehicles, leading to inconsistent starting issues and poor engine performance. The camshaft plays a critical role in controlling the opening and closing of the engine’s valves, which is essential for proper air and fuel flow as well as exhaust removal. When the camshaft is worn, it disrupts valve timing, leading to a host of issues, including difficulty starting the engine.

This article will guide you through diagnosing a worn camshaft, understanding its impact on your vehicle, and how to repair or replace it.

What Is a Camshaft and How Does It Work?

The camshaft is a component of the engine’s valvetrain system, and its primary job is to control the timing and operation of the engine’s intake and exhaust valves. It does this by using precisely shaped lobes that press against lifters or rockers to open and close the valves in sync with the engine’s pistons.

When the camshaft becomes worn, its lobes lose their shape or develop flat spots, which can prevent the valves from opening and closing correctly. This affects the engine’s ability to breathe properly, leading to poor performance or difficulty starting.

How a Worn Camshaft Affects Valve Timing and Starting

1. Inconsistent Valve Operation: A worn camshaft can cause the valves to open at the wrong time or not fully open, leading to improper combustion and reduced compression.
2. Loss of Compression: Valve timing issues can reduce compression in one or more cylinders, making the engine harder to start.
3. Misfires: Worn cam lobes may cause incomplete combustion, resulting in misfires that make starting difficult.
4. Poor Fuel Economy and Power Loss: The engine struggles to maintain efficiency, causing reduced fuel economy and power output.

How to Diagnose a Worn Camshaft

1. Listen for Unusual Engine Sounds
   • A worn camshaft often produces a ticking or knocking noise due to improper valve operation. Listen for these sounds when the engine is running.
2. Check for Performance Issues
   • Symptoms like rough idling, misfires, or difficulty starting can indicate a worn camshaft.
3. Inspect Compression Levels
   • Perform a compression test on each cylinder. Low or uneven compression across cylinders could point to valve timing issues caused by a worn camshaft.
4. Visual Inspection
   • Disassemble the engine to inspect the camshaft. Look for flat spots, worn lobes, or scoring on the camshaft surface.
5. Use an OBD Scanner
   • If your vehicle has an OBD system, scan for trouble codes related to misfires, valve timing, or camshaft position sensor errors.

How to Fix and Repair a Worn Camshaft

1. Determine the Extent of Wear
   • Minor wear can sometimes be addressed by regrinding the camshaft to restore its shape. However, severe wear will likely require replacement.
2. Remove the Camshaft
   • Step 1: Disconnect the battery and drain the engine oil.
   • Step 2: Remove the valve covers, timing components, and any accessories obstructing access to the camshaft.
   • Step 3: Carefully remove the camshaft while noting the alignment of timing marks.
3. Inspect Related Components
   • Check the lifters, rockers, pushrods, and timing chain/belt for wear or damage. Replacing these parts along with the camshaft is often recommended to ensure proper operation.
4. Install a New or Reground Camshaft
   • Install the new camshaft, aligning the timing marks correctly.
   • Replace the timing chain or belt if worn, and reassemble the engine components.
5. Adjust Valve Timing
   • Use the engine’s repair manual to set the correct valve timing. Incorrect timing will continue to cause performance issues.
6. Test the Engine
   • Refill the engine oil, reconnect the battery, and start the engine. Listen for any unusual noises and check for smooth operation.

Preventing Camshaft Wear

1. Regular Oil Changes
   • Proper lubrication prevents excessive wear on the camshaft and its associated components.
2. Use Quality Oil and Additives
   • High-quality engine oil and additives can protect the camshaft from premature wear.
3. Perform Routine Maintenance
   • Regularly inspect the timing components and ensure proper tension in the timing chain or belt.

When to Consult a Professional

If diagnosing or replacing the camshaft seems too complex, consult a professional mechanic. Working on the camshaft requires precision, and improper installation can lead to further engine damage.

Final Thoughts

A worn camshaft can disrupt valve timing and lead to inconsistent starting and performance issues, especially in older cars. By learning to diagnose the problem and either repairing or replacing the camshaft, you can restore your engine’s performance and reliability.

Remember, while the process requires attention to detail, addressing camshaft wear promptly can save you from more extensive engine damage in the long run.