Residual stress distribution at the cylinder block wall in 1500cc class aluminum engine was measured using RESA in JRR-3 of JAEA. In order to increase neutron flux at the gauge volume measured, newly developed incident beam slit was employed. Since the grain size in cast aluminum engine block is expected to be large, the oscillation method was applied. The residual stresses near the surface layers of cylinder block wall were compressive all in the tangential, the thickness and the cylinder axial directions, but tensile in the meddle part of cylinder block wall. This means the residual stress distributions are likely to be hydrostatic. The residual stresses in the tangential direction were not balanced in the cylinder block wall. This is caused by the measurement error or the bad accuracy in the measurement of strain-free lattice parameter. If the stresses are modified to be balanced, the residual stresses near the surface were -70 MPa.
