Do I repair, scrap or break my motor w203 C Class 2005 105k

[markjay]

Would the bottom sprocket need replacing?
Water pump?

Not as a matter of course, replace on condition.

The original coolant is actually very good and does not need relacing before 2020 (it's a 15-year coolant). So if the car still has the original factory coolant then the internals of cooling system will be in pretty good condition, with little corrosion or sediment. So in essence if the coolant pump bearing isn't noisy, there no play and no leak, than there's no need to replace it. Said that... if you can get one on the cheap... you could argue that 'while you're there' you might as well get it done.

 

[jpod]

With regards oil, has the engine been serviced with the correct MB-Spec oil (229.3 or 229.5) throughout its service life?

Noted. Regular oil change with the right stuff in my ownership last 35k. Not sure on the coolant.