Black smoke advice requested

My beloved Sprinter motorhome is based on a 1998 410 with the 2.9 5 cylinder diesel engine. She has 280k miles on the clock and still runs well and always starts on first touch of the key. At tick over there's not much to be seen from the exhaust but on acceleration there is a billowing black cloud of soot. I have changed the air filter and put a bottle of Cataclean in the tank. Can anyone relate to this problem and its cause.? All advice will be appreciated.

That will have a mechanically injected diesel. I believe it has electronic fuel control though? How is the power, do it still drive okay?

How is the air filter?

Any sign of boost leaks?

Does it have a manifold air pressure sensor?

Is the EGR valve really necessary?

My Sprinter is a 1998 410D with the "old" 2.9 5 cylinder engine which is totally reliable. However during the summer it started to emit dense black smoke when accelerating. After trying the usual things such as new air filter and fuel additives I took it to a local Sprinter specialist. After doing some tests he pronounced the engine basically healthy and the solution to the smoke problem was to disconnect the vacuum pipe from the EGR valve. The effect has been dramatic and not only is there now barely any smoke the engine is producing more power which is quite evident on hills. My question though is should I leave it as it is with no EGR? There is no problem with electronic warnings as the EGR valve is purely mechanical. Or should I take steps to discover why the smoking occurred and put things back to normal. Has anyone else experienced this?

Re: Is the EGR valve really necessary?

This question might receive more attention on the T1N Talk forum. I didn't read through it, but there is another thread for an EGR valve issue there.

Sounds like your EGR valve was sticking/leaking. On your engine there will be no negative effects of disabling EGR flow. Well, other than increased NOx emissions.