My cat e200b started bogging down under load about a week ago with a lot of black exhaust smoke. Changed the oil and filter, hydraulic filters, air filters, no change, mechanic came out to look at it, said it could be the diesel injection pump, started taking that of and took the valve covers off and the front head was all sludged up, meaning not much oil was getting to the valvetrain. Now he says the engine needs to be overhauled, he overhauled it 3 years ago. Are the the problems related or now 2 separate problems. Anyone have any ideas of the next step, or just go ahead with the overhaul. Thanks for any input. Rick.