Camshafts are responsible for timing the opening and shutting of engine valves, and as such are integral to the engine’s mechanical performance. Cams may be made of solid steel, low-grade steel or iron. They run the length of the engine head and have uneven-looking lobes set at regular intervals along the shaft. Under normal conditions and with adequate preventive maintenance, camshafts should last a great many miles.
As the engine runs, the cam turns using a chain or belt attached to the end of the crankshaft. This pushes the rods along the lobes, applying pressure to the valves and forcing them open during that phase of the engine stroke. The movement of the lobes then allows valves to close once the stroke ends. Lobe shape regulates engine timing and the time valves spend open. As such, lobe shape directly affects engine performance.
Symptoms of Camshaft Problems
- Failing camshafts make a “ticking” sound or “valve clatter”
- Engine makes “popping” sounds or backfires
- Poor gas mileage or poor engine performance
- Trouble starting
- Signs get progressively worse
- Dark, oily exhaust
If the valve train fails completely, the vehicle is immobilized. Fuel delivery and exhaust removal do not function.
Reasons for Camshaft Problems
- Failing camshafts usually signal other problems
- Cams fail due to other problems in the engine’s valve train.
- Oil can be starved in the engine head, causing increased friction where the cam and rods meet, or causing excessive heat on the cam
- Rocker arm assemblies can be adjusted incorrectly and cause binding
- Valve springs may bind or break
- Occasional manufacturer errors of shipping damage to the cam
- Pitting or scratching on the camshaft from contaminated lubricants
- Mechanical and material stress over time
- Failure to change the oil and adjust valves as recommended
- Poor quality fuel or contaminated oil
Repair and Replacement Costs
- Replacing camshafts requires disassembling the engine timing components including belts and pulley.
- Camshaft replacement requires intensive and difficult labor, driving up costs.
- Camshaft replacement can cost between $1500 to over $3000, depending on the car and the repairs required.
- The price of the camshaft alone can be between $250 and $1000 or more, depending on the model of the car.
- Foreign camshafts may cost two to three times more than domestic ones.
- Labor prices may be anywhere from $20 to $100 per hour
- The average camshaft repair takes five to seven hours
- There will be additional costs for engine parts that support the camshaft and the engine.
- A camshaft position sensor will be needed, costing upwards of $150.