318 TDS chain problems

Hello everyone.
I am relatively new in this forum and I would like to make a consultation ... I have a BM 318 TDS with 185,000 km, recently began to make a CLAC CLAC when starting my car, consult and tell me that it is the distribution chain / tensioner, they have an idea if to make the change you have to take the engine or can be done without disarming half a car.
Thank you very much to all .. greetings.