Did you just put a piggy bank on top of your engine's valve cover? Because that grinding and rumbling noise coming from under your hood sounds like it. Rev your engine up. Does the sound's pace keep up with the engine speed? Oh no-you've done it. At least one timing chain tensioner has worn out and it's left the timing chain loosely running over the sprockets. You weren't really aware that a timing chain has to be replaced every 100,000 kilometers, were you? Great! Now you've got a serious problem in your eyes, and the longer you keep running your engine, the more chances of repair costs growing exponentially. So shut off your engine-now!It's time to open up the timing chain cover and eyeball the ruins. In case you weren't aware, engines such as yours use a timing chain to keep the engine in proper timing. It connects the camshaft with the crankshaft, keeping them in sync with one another. And just as timing belt failure would cause severe engine damage, so will timing chain failure. Fortunately, chains are much more durable-and the timing chain tensioner is usually the first to fail. So you'll get a warning that the chain is about to sign off-the grinding sound you heard earlier.Once the timing chain tensioner fails, the timing chain loosens its hold over the cam and crank sprockets. It'll only be a matter of time. Chains and tensioners are available here at Car Stuff.