  By observing the interacting galaxy NGC 3627 in radio polarization we try to
answer the question to which degree the magnetic field follows the galactic gas
flows. We obtained total power and polarized intensity maps at 8.46 GHz and
4.85 GHz using the VLA in its compact D-configuration. In order to overcome the
zero-spacing problems, the interferometric data were combined with single-dish
measurements obtained with the Effelsberg 100-m radio telescope. The observed
magnetic field structure in NGC 3627 suggests that two field components are
superposed. One component smoothly fills the interarm space and shows up also
in the outermost disk regions, the other component follows a symmetric S-shaped
structure. In the western disk the latter component is well aligned with an
optical dust lane, following a bend which is possibly caused by external
interactions. However, in the SE disk the magnetic field crosses a heavy dust
lane segment, apparently being insensitive to strong density-wave effects. We
suggest that the magnetic field is decoupled from the gas by high turbulent
diffusion, in agreement with the large \ion{H}{i} line width in this region. We
discuss in detail the possible influence of compression effects and
non-axisymmetric gas flows on the general magnetic field asymmetries in NGC
3627. On the basis of the Faraday rotation distribution we also suggest the
existence of a large ionized halo around this galaxy.
