Caterpillar Engines 3512B

MY Grandpa worked on those engines for most of his life. I spent some formative years learning a bit here and there.

Unless the technology has changed a great deal in the past 35 years. those machines always put out the black cloud as a load is applied. Then settle down to a lighter color as momentum / some speed is reached.

Black smoke under a load usually means a leaking fuel injector a clogged air filter can cause some smoke too.

the cause of black smoke can be one of the following : -Injectors -Pump that needs recalibration -Adjustment of air fuel mix -Low compression : piston , piston ring or liners worn out -Valves leaking due to worn valve guides -oil pressure high : faulty oil pump relief pump .Usually the pressure should be between 2 bar at normal operating temperature (10 bars @ startup) Usually there is a smoke measuring device that allows you to identify the amount of smoke and compare it to the standard.This standard is usually obtained from the permissible values for your country (motor vehicle inspection agency). I hope this could solve the problem. Kamal

Hi,

Black smoke from a diesel engine means one thing; un-burnt fuel. Kinda like when you see trucks racing, they belch the stuff. The reasons could be many. Kamal suggested quite a few. Talk to an old diesel mechanic, he should be able to help or at least put you on the right track.

Under a load, black smoke is a normal condition for a deisil. Some of the more modern machines play with the timing to better control it, but it is cause from unburnt fuel.

If the injectors are not atomizing the diesel properly then the droplets sizes will be larger and harder to burn. Under load the fuel system will automatically increase fuel to compensate for the demand in power. Since the additional fuel is not atomizing properly the un-burnt fuel comes out as black smoke. The injectors will need to checked to reset the pressures, fuel delivery and timing of fuel injected. The problem with fuel that doesn't burn properly results in diesel mixing with oil. This causes the oil to thicken into a sludge and result in early engine failure. Take a sample of the engine oil to a lab for analysis to see how much diesel is getting into the oil.