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7.3 diesel, turbo wastegate operation
I am working on a friends 99 E350 cab and chassis, with the 7.3 turbo diesel, that used to be an ambulance. It has about 230,000 miles and feels like it has no power.
The issue I have found I think will fix my problem, but I am not sure how to fix it or why it's doing it.
The turbo wastegate is stuck open. Wide open. All the time, engine off, engine on, idling, full load and part load. It appears to be a mechanical wastegate, operated by a spring and rod that is housed in the pedestal on the bottom of the turbo. I took it apart and all is there according to the diagram. I can push on the rod (it's hard because of the high spring tension) and watch the gate open and close, but it never works naturally (when the engine is under load. I understand the responsibility of the turbo and a wastegate, but am not familiar with the Ford theory of operation.
I hear the turbo want to spool, and the fan blades inside look good and spin freely with my hand. I just think it's dumping its boost all the time.
Do I have an oil pressure problem or a turbo that is not sucking the wastegate shut? How is this supposed to work?
Any suggestions would be appreciated, thanks in advance.