Briefly, I have a 1972 ser 3 diesil 2.25. Engine is rebuilt and runs very nicely. Very little visible smoke on tickover but when driven along under load black smoke is visible. I have played around with the pump timig and this is as good as it gets. Doesnt seem to use much oil so the smoke seems to relate to fuel usage. I am told this is normal for a diesil truck from this era but just wanted to get some advice. Does the MOT relate to a visual check ie at tickover? Is black smoke typical on acceleration? Appreciate your comments. Thx. Mike

whats the smoke like if you rev the engine up and hold the throttle steady at say about half revs when the vehicle is stationary

have a look here

MOT UK car and vehicle MOT information equipment car servicing parts and spares - suspension wheel bearings drive shafts