it shouldn't be hard. my 318 is likey a very similar system. the tensioner is accessible from removing only the upper timing cover. however, as was recommended to you you likley wont need to work on it; considering you keep your oil topped off well the chain wont wear excessivley. in the case that it begins to, it will become very obvious from the loud rattling noise that will seem to come from the valve cover. To inspect, remove your valve cover (the gasket is a rubber reusable so inspecting takes only tools and time). From there you can see your cams, camgears, timing chain and the top chain guide; it'll be pleasing to find a clean shiny chain. To get to the tenioner you must then remove the timing chain cover (there will be paper gasket that will need to be replaced).
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