Engine Parts - Turbocharger S400 174834/173299

Engine Parts - Turbocharger S400 174834/173299 — Exhaust-driven turbocharger (S400 series): exhaust gas spins the turbine, which drives the compressor on the same shaft, and the compressed charge raises air density and output without increasing displacement. Inside one series there are variants differing in pressure ratio, turbine housing A/R and direction of rotation; they look alike but do not interchange, so selection must follow the complete model and part number on the engine plate and on the old unit — photographs or overall dimensions alone will get the order wrong. Before fitting, check the exhaust manifold flange face for warping, look for foreign objects in the intake tract and measure turbine axial and radial play against the limit. Change the engine oil and oil filter at the same time, confirm the oil return line is clear and not crushed, and let the engine idle for half a minute after the first start so oil reaches the bearings before load is applied. Most turbo failures come from oil starvation, dirty oil or dirt entering the intake; rule those three out before fitting a new unit, or it will fail the same way again.