Identifying issues on diesal engines

mondeo

When buying a diesal van or car is the same principle applied for....
How do I know if the thing is burning oil etc? On a petrol car it is blue smoke but is it the same on a diesal? What colour emmisions should I expect to see when I redline a diesal motor? How would I identify bottom end knocking etc when the diesal engines in general are already rather noisy?

Cheers

peasant

The usual checks for oil in water / water in oil still apply to diesel engines. Burning oil also still burns blue, although it might be a bit harder to spot among the diesel soot. Redlining a diesel when stationary shouldn't result in much (but please don't do it on a cold engine) under acceleraration however, black smoke is quite normal, especially on a turbo.

Overly smoky engines needn't necessarily be broke, the injection timing/amount could just be off.

General rule of thumb (veeery general ) when you're driving , you shouldn't really be aware of smoke, once it becomes noticable in the mirrors, something is usually wrong.