We have a Hyundai Sonata 2003, 4cyl, 140,000 miles and what is happening is that there is a loud thumping noise comping from the area of the timing belt cover.
The belts, timing included were replaced at 120,000 miles and the noise started at around 130,000. At 132,000 the noise became quite annoying so we took it to the dealer, the verdict, the timing belt cover had become warped and was showing signs of scuffing on the inside. The dealer replaced the cover and all seemed well, for a while at least.
We now have 140,000 miles on the clock and the same thumping noise is back and louder than ever. After the car has been driven on the highway, once parked, there is an odor of hot plastic/rubber from under the hood.
Poking around trying to find the source of the noise the only thing I can seem to discover is that touching the timing belt cover even slightly changes the thumping noise to more of a rattle.
I am scheduled to take it back to the dealer, but I was wondering if anyone here has any idea, as replacing the cover was only a temporary fix.
To attempt to illustrate the problem here is a short video of the noise.