apart from rust (which should be fully apparent by now if its a problem) the CDI engine is a cracker. My sprinter has the same engine and 310k on the clock. One thing to have a look for is the injector seals can start to leak – you’d hear that as a sort of chuffing noise at the top of the engine or look for a sort of hard black, plasticy marmite like deposit seeping out from the plastic cover in the top of the engine.
The seals only cost a few pence but garages can make a mince of a job of changing them – charging over a grand for the work sometimes, and never giving a firm quote as they are nervous about the work, and if they don’t dress and seat the new seals properly the problem just recurs
Injector seals are pretty much the engines only achilles heel – mainly because they sit in a gully in the top of the engine that ends up encased in this black crud (its actually part burn diesel) that has to be chiselled out. Access to the bits is tricky and folk can snap bolts in the head or even crack top of the engine. Lots of folk have tricks using oven cleaner and stuff that makes the problem worse rather than better
Hammer the price down if thats happening there are any symptoms of this (they’ll probably already know about it and thats why they want shot)- but a bit of spirited google foo there are travelling CDI injector specialists (who only work on merc injectors and seals) who can do the work on your doorstep for a fixed fee of £300 – £400 and warrentee the work too. (I’ve still got the details for the guy that did mine somewhere)
