Technical Black smoke

[Aquatic gypsy]

Hi folks I have a 2
8 jtd 51plate in a camper and it has started to black smoke under load and also it keeps jumping out of 5th or won't go in

 

[bugsymike]

Hi folks I have a 2
8 jtd 51plate in a camper and it has started to black smoke under load and also it keeps jumping out of 5th or won't go in

Generally diesels chuck out black smoke for one of two reasons, too much fuel or not enough air (oxygen).
No1 Worn injectors or pump popular causes. Due to high mileage. Also faulty sensors or wiring plugs.
No2 Blocked air filter restricting air to engine or not enough turbo boost, split pipes,intercooler, worn turbo etc.
Re gearbox check for worn linkage first , then look at gearbox.