Diesel smoking

I have a 4D55 recently rebuilt engine. The injection pump, injectors and turbo have not been rebuilt. Under normal driving condition with minimal load the truck does not smoke. If I'm going up a hill or under acceleration there is a constant stream of black smoke coming out of the exhaust. Could this be that the injection pump timing is off? Turbo wore out? Injectors in need of rebuild? The other night I tore the injectors apart and cleaned them (they had some build up in them; fixed my miss when first started up when cold).

Diesels do that.

I have seen guys do that smoke stuff at intersections trying to be a smart ass, not sure what is so funny about it, but they seem to have fun doing it.

I do that with my cummins when the person driving on the passenger side has been a tard.

Pep boys really pissed me off about 20 years ago so after I watched them put my diesel alternator on their test bench and "give it a spin" , I laughed as the left over oil in the vacuum pump squirted up to their ceiling and on the guys shirt.The guy never expected black oil to come out of an alternator! Than I backed up my diesel to the front entrance push in the clutch and as the door opened gave them a black smoke cloud by pressing the gas and running it up to 3000 rpm LOL!!!

The timing will def have an impact on the smoke. Did your injector tips look flat on the end or are they dished like a crater on the moon? They probably drip and do not seal . Our lo sulfur diesel has zero lubricity so you are junking your fuel system if you are not using a good diesel additive. The fuel injection shop even told me once they introduced low sulfur diesel he saw mechanical type injection pumps and injectors failing much faster than ever! So use a good additive it's totally worth it. I recommend stanadyne

No one really addressed your question, so I'll give it my best. Yes, diesels smoke. Why? When they have less air available than is needed to fully burn the amount of fuel being injected. This is usually at low RPMs before the turbo has a chance to spin up and provide enough air. However, since yours is doing it steadily at while under load, you're turbo should be providing plenty of boost to keep it burning clean.

So, do you have a boost gauge? If so, what psi are you getting when under load like that? If not, get one! The turbo would definitely be my first suspect.