What's the matter with incorrect exhaust camshaft assembly?
3 Answers
In this case, it is necessary to inspect the engine's variable timing system, specifically whether the oil solenoid valve of the VANOS system is functioning properly. Check the solenoid valve's resistance value, wiring, and whether the solenoid valve spool is stuck. If stuck, try cleaning it! Additionally, inspect whether the exhaust camshaft position sensor is working correctly. If necessary, examine the electronic valve system, namely the VALVETRONIC system. Introduction to Camshaft: The camshaft is a component in a piston engine. Its function is to control the opening and closing actions of the valves. Although in a four-stroke engine, the camshaft's speed is half that of the crankshaft (in a two-stroke engine, the camshaft's speed is the same as the crankshaft), its speed is generally still very high, and it needs to withstand significant torque. Therefore, the design requires high strength and support for the camshaft, and its material is usually high-quality alloy steel or alloy steel. Camshaft Structure: The main body of the camshaft is a cylindrical rod approximately the same length as the cylinder group. It has several cams mounted on it to drive the valves. The camshaft is supported within the camshaft bearing holes via camshaft journals, so the number of camshaft journals is an important factor affecting the camshaft's support stiffness. If the camshaft's stiffness is insufficient, it may bend and deform during operation, affecting the valve timing.
When there was an incorrect assembly of the exhaust camshaft in my car, I experienced strange engine noises and poor acceleration. It was last winter when I felt the car was particularly sluggish to start, accompanied by a rattling noise. I looked it up and found that the exhaust camshaft controls the opening and closing timing of the exhaust valves. If it's misaligned or the belt is loose, it can cause uncoordinated ignition and emissions. At the time, I thought it was just a simple chain issue, but upon inspection, it turned out that the timing marks weren't aligned during installation, causing the camshaft angle to shift. This meant the exhaust valves didn't open when they should, affecting the entire engine's power output. Fortunately, I went to the repair shop in time, and the mechanic readjusted the timing system, restoring normal operation. Since then, I've always had the camshaft-related components checked during every maintenance to avoid similar issues caused by aging. If the exhaust system is misaligned, it not only wastes fuel but can also damage the catalytic converter, making repairs more troublesome. I recommend that if owners hear unusual noises or notice poor acceleration, they should promptly consult a professional instead of delaying like I did, which led to engine overheating.
Misalignment of the exhaust camshaft assembly is commonly caused by improper timing system alignment, such as loose or shifted belts/chains, or angular deviations during component installation. As a mechanic, I've handled numerous similar cases—the camshaft controls exhaust valve timing, and incorrect positioning disrupts gas expulsion, leading to unstable engine performance. Symptoms include sluggish acceleration, increased fuel consumption, and occasional black smoke. Diagnosis requires specialized tools to verify cam timing marks synchronize with the crankshaft. DIY attempts risk worsening the issue. For prevention, routinely inspect drive belts during maintenance and change oil regularly to minimize wear. Improper assembly may also damage valve springs, incurring costly secondary repairs. Prompt troubleshooting is crucial—never ignore subtle warning signs like heightened vibrations. Car owners can benefit from learning basic maintenance to save time and hassle.
