OM636 Engine Smoking and Popping

[deepthought]

I have an Mercedes OM-636 engine. The other day when we where out it started making a popping sound and seemed like it was loosing power. It sounds like its from the air intake. So I shut the engine down and made a quick check of all the usual fluids (oil, radiator) everything seemed fine.

I tried to start it again but it wouldnt start. So I went back to the engine and started checking again. And found the Fuel filter looking a bit dirty so I removed them and replaced them with new ones.

Tried starting again and it very hard to turn over. I almost have to hold the starter on for 20-30secs to get the engine cranked over.

Anyways it started but still with the noise and if I have it in a lower idle and put it in gear it will die.

I made it back and as we where getting back there was a bit of white smoke coming out. so we dropped anchor and shut down the engine for the night.

Yesterday again I got it started with difficulty when I started it a lot of black suit falls into the water from the exhaust. And now there seems to be more of a blackish smoke.

Theres no metallic knocking sound no water in the oil or oil in the radiator.

There is gas going to each of the injectors the internal fuel filter is clean.

I was playing around this morning with it and cranking it a little and noticed that the number #4 (last glow plug) felt burning hot while the others where cool but I am not sure if that is normal or not.

I brought it to a yard here where we currently are anchored and they want 1000eurs just to take the engine out and then go from there. It seems a bit high so I am hoping I can find some suggestions or I will sail back 100miles to another mechanic if I have to since I know his prices where reasonable.

Any help would be greatly appreciated. Can give any more info if requested or post pics or videos of anything if needed.

Can also try anything and post results.

Thanks