Looking at buying a family hauler for my growing family. We currently have a 2016 ford escape with the 2.0 ecoboost. Nothing wrong just too small for a family of 3 soon to be 4. Found a 2014 Sienna at my local toyota dealership with 122k miles. They are asking 17.3K. Quick overview it seems pretty solid. Only issue we found on a test drive was that the back up camera was not working. Just a black screen. The salesman said he is going to have the service department look into it. The engine bay looks clean and no leaking fluids. However when i looked at the bottom of the timing chain cover through the passenger wheel well i saw a bit of seepage. Given the miles I asked to see the service record and the timing chain has not been serviced. What is the life of the timing chain? Should I push to have it done before purchasing? 

Thanks!