i have a couple 627a twin engine scrapers i just got. all four engines start right up real good. all have 3306 engines. the problem is when the fronts are under load they smoke [black] like banshees and dont put out. i did oil change and primary fuel filters to no avail. in park they smoke off idle smooth out until 3/4 petal and smoke heavy black. i checked the screw in sediment bowl screens one had shavings in it. the other did not. the one with shavings can hardly pull it self around. but it runs good. these machines sat @ 3 years. Thanks any advice?
the air cleaners are fine
Turbo's? afc's?
how do yo check afc's
i own detroits an cummins, this is my first pair of cat engines so please bear with me. I am finding operating a scraper and fixing a scraper two way different things. I should have paid more attn when i broke down years ago. I have a new respect for mechanics. afc ..... i assume you are talking about a diaphram? i dont know where its at. As far as turbos what is the best way to check them. thanks Cat--tarded for now. thanks
There is a rubber diaphragm in the air ratio valve on the back of the governor that will tear and need replaced. There will be a hose going from it to the intake.
If they smoke that much they are getting fuel. AFC (air fuel ratio control) holds the rack back untill the turbo produces enough "Boost"(air pressure) to burn it clean. If the afc has a bad diaphragm it might have been adjusted out of the way. Really need to measure boost at intake manifold and engine speeds to know more.if they have "Retarders" they might be on. They can load an engine right up so it can't haul, Great for testing an engine though. Later Bob
You turbos are not lighting and coming to boost fast enough and the engine is bogging down. Check your intake systems and filters, then check your turbos.
You may want to have your pumps checked out. I have seen some strange things done in a misguided attempt to get more power that just creates smoke and nothing more. If its the same issue on 2 machines, from the same place... JMO
Afc!
got um fixed 1 turbo and some nozzes in the other. but thanks for helping everyone.