As far as I can tell the engine has never been worked on, although I have done the cam belt kit a few years ago just to be on the safe side. At the last pollution check (which is a good guide as to whether the engine is worn) the opacity limit for a non-turbo diesel of that age is 2.5m-1. The actual figure was 0.36m-1 so no worries there.
Whilst the van is still "dans son jus" on the outside, (it's a bit battered) it has been completely "refreshed" mechanically. Last tankful it averaged 49.1 to the gallon. It's my daily driver.
I have had two Citroen Visas in my life in the past, which is the car version of the C15 van and loved both of them. The first I one I bought in 1983 was a six month old demonstrator from Newcastle Motors in Telford which I sold after four years and 100k miles to a family member who ran it for a further six years before selling it on. It was replaced by a new FSO P125! (The less said about that, the better). The second one was a blue 1985 car bought in 1991 and again kept for three years until replaced by a Rover 2300. Both cars were fun and reliable. The first had the early ‘spacecraft’ dash and switch arrangement . The second one had thelater more normal controls. Miss the Rover, though. But I’d have another Visa tomorrow if I could find one.