My ML270 and 300D produce a lot of black smoke. Every time I rev it, there is smoke coming out. Is there a way to remove this?

 

I don't know what a ML270 is.

It would be nice to know what year 300D (If it has a Turbo the Turbo Seals can leak into the Exhaust and cause smoke) you have and how much mileage is on the Engine.

If you are driving and the Engine is nice and hot and there is no smoke but when you step on the Accelerator Pedal really fast and Hard it is normal for there to be a bit of Black Smoke but that should clear up quickly.

If You are laying down smoke screen of Black Smoke that is not normal.

When you first start the Car and the Engine is cold if the Engine is in good condition you should barely or not see any smoke white or gray and especially not black smoke.

Causes; I noticed when I was in the Philippines at least out in the Provinces that I saw a lot of Vehicles that needed repair or their Engines were worn out but still running on the Road.
Perhaps they can't get away with that in the larger Cities due to Smog..

So in general Black Smoke is partially or not well burned Fuel.
That can be caused by not enough Air like a Air Filter that is plugged, poor Compression in the Cylinders or if the Injectors are not atomizing the Fuel Well.
Besides wear in the Cylinders, Pistons, Piston Rings not have the Valves adjusted can effect the Engine Compress as can late Valve timing due to Timing Chain/Gear Stretch/Wear.

Here in one of our Colder States if your Engine compression was bad you would notice hard starting; but in general the Philippines is a warm weather Country and that might not be as noticeable.

If you are burning any Oil the Smoke may be more blue in Color and it will smell to some extent like burned Oil. That can be Cylinder, Piston, Ring wear and leaking Valve Stem Seals and worn Valve Stems and Guides.
Members of another Forum have said if the Little O-ring in the Fuel Supply/Lift Pump goes bad it can suck in Oil from the Fuel Injection pump and that will burn in the Cylinders.
For the Oil burning issue you should notice you need to add Oil to keep the Oil level normal.

Another smoke issue could be the Fuel quality. My Wife has been telling Me the Prices on Fuel in the Philippines has been going up. It could be someone is adding stuff to the Fuel or simply buying the lowest grade Fuel possible.

If the Engine has a Turbo Charger it may be possible to adjust the ADLA to reduce the Tail Pipe Smoke but that also normally reduces the acceleration/power.

If it were me I would start of with adjusting the Valves as that does not cost anything if you do it yourself.
If the Valves had not been adjusted for a long long time after the Valve Adjustment drive the Car a few 100 miles and do the Valve adjustment again.

Having a Compression Check done may give some idea what is going on concerning wear in the Engine. Do the Valve adjustment before the Compression Check is done.

 

Thanks for the tip. My ML270 is an SUV and the 300D is a '92 model.