Hi all, first post here. I was googling something when this thread caught my eye. I figured I'd sign up. I work on Hino trucks and I have some input.
How did the turbo fail? Usually, either the VNT controller is damaged, or enough radial play develops in the bearings that it can't control oil any more, or the compressor wheel starts rubbing the housing. It's serviced at the dealer as a complete unit, the VNT controller is not available separately on all models previous to '11. In '11-up, the VNT controller was improved. Nickel antiseize on the VNT rod pivots keeps it moving smoothly. Places where road salt is used can partially seize the linkage, causing VNT controller damage.
Someone mentioned oil cooler o-rings. Yeah, they leak. Gotta pull the turbo to remove the oil cooler. The oil cooler will leak both coolant and oil, oil from the o-rings and coolant past the factory rtv sealant. I can't recall when exactly, but the surface of the oil cooler housing got an update, the center of the flat surface was ball-milled to help retain the sealant. It's much better, but occasionally even the updated ones will start seeping. Right Stuff RTV, which comes in a tube for a caulk gun, seems to solve the problem permanently. When you go in to remove the turbo, don't remove the elbow that directs the exhaust downward. Take the four elbow-to-pipe nuts off, drop the first pipe clamp and loosen the second (under the truck), then take a 14mm socket just under the elbow and take the one bracket nut off. Two more support bolts under the turbo come out, then it's just coolant and oil pipes, and the four turbine housing flange nuts/bolts. Oh, and all the intake piping and stuff. The black sealing washers (aluminum with sealant coating) can be reused if the coating isn't scratched or flaking off. Use a torque wrench to reinstall the oil cooler housing. Never seen one warp, but I'd rather not be guilty. The actual oil cooler element itself is very robust and very rarely fail.
