This is a project that came to us yesterday. This turbocharger was removed from an industrial turbo diesel Caterpillar engine. This turbo has a twin scroll turbine housing and utilizes 2 wastegate valves. After heavy use the turbo wastegate valve failed completely and broke off from the flapper arm. This caused the engine to produce almost no boost pressure, rendering the work truck inoperable, costing the company money while out for repairs. Replacement parts for this turbo are not available from Caterpillar or the turbo aftermarket. Only option was turbo replacement, at a cost of $1500. There was nothing wrong with the turbocharger other than wastegate failure and rendering it useless was not an option.
Turbocharger was disassembled and turbine housing media blasted by hand. During disassembly process all 4 retaining bolts sheared off inside the housing despite extensive heating. All broken bolts were drilled out and retapped to proper size. New stainless steel bolts used for mounting of the CHRA to the turbine housing.
We opted to machine our own replacement wastegate valve and perform necessary repairs in a timely manner. New wastegate valve was machined from 304 grade stainless steel in a lather using same dimensions as the other, still functional, valve. New valve was welded to the flapper arm allowing for motion same as original one. The flapper arm was reinstalled in the turbine housing and welded to the actuator level arm. Turbocharger was reassembled and proper wastegate actuator operation confirmed.
Turnaround time for repair was one day; even less than ordering a new turbo!
Below you will find pictures of the repair process: