You may be surprÂ­ised to discover that a carbon monoxide (CO) detector really isn't a complicated piece of equipment. Housed inside a plastic chamber approximately 3 inches (7.6 centimeters) in diameter are parts that work in unison to alert a househoÂ­ld when lethal gas is detected.
This type of noise is usually caused by malfunctioning valve lifters or an exhaust manifold leak. If the noise lasts for more than a minute and completely disappears or dimishes after the engine is warm, the most likely cause is an exhaust manifold leak.
Middle ear effusion (fluid) is probably the most likely cause of this odd crunching sound, but there are other causes, such as TMJ dysfunction, and myoclonus. Decongestants are far from miracle cures and it is controversial whether they help or not. Mucolytics (like Mucinex) are in the same questionable catagory.