You used the term "timing chain" and belt in your post.
Just know that you do not have a belt that connects your crank to your camshafts. You have a chain.
The usual symptom is a slapping noise at start-up. This is a loose chain slapping against the plastic guides, and this is what usually causes your engine to break.
The loose chain slaps against the guides at start-up. The plastic guides are old and the plastic is brittle. The plastic breaks and the bits and pieces get stuck in the chain and the cam sprocket. The chain stops turning, and the result is the valves will hit the top of the pistons, and your camshaft(s) will likely bend.
This is sooooo common on the V8 engines (116, 117, 119) that I bet every MB shop does several every week. This forum is full of engines where this breakdown happened. There are at least two active threads where this occurred.
I'd guess if it breaks you're looking at $4,000????
If I were you, I'd replace the chain, guides, and tensioner every 100,000 miles.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".