As part of preventative maintenance on my 1987 190E 16V I plan to replace the timing chain, the top guide rail, and the chain tensioner . This is the most I can do without removing the timing cover, which is a very big job on this car. This means I will not be replacing the tensioner rail or the other two chain rails that can only be replaced by removing the timing cover.

My 190E 16V has approx 156,000 miles on it. I bought the vehicle with 39K miles. The timing chain has always had a very brief rattle on a hot engine start up, especially on a hot Calif day. This has never gotten worse or more pronounced. The chain never makes any other noise. I check the valves every 15K miles and have never seen any visual signs of chain wear. I use Mobil 1 oil changing every 7000-7500 miles.

Question: Is it adequate preventative maintenance to not replace the tensioner rail and the other two rails that require removing the timing cover? I know the rails can break and do major damage, but do I avoid the major risk by replacing the chain, upper guide, and tensioner?

Thank you--Jim Herold