  We report the results from pulsations and spectral analysis of a large number
of observations of the HMXB pulsar IGR J18027--2016 with {\it Swift}--XRT,
carried out at different orbital phases. In some orbital phases, as seen in
different XRT observations, the X-ray intensity is found to vary by a large
factor, of about $\sim$50. In all the observations with sufficient number of
source X-ray photons, pulsations have been detected around the previously known
pulse period of $\sim$140 sec, When detected, the pulse profiles do not show
any significant variation over a flux difference of a factor of $\sim$3. The
absorption column density is found to be large before and after the eclipse. We
discuss various possible reasons for intensity and spectral variations in IGR
J18027--2016, such as clumpy wind and hydrodynamic instabilities.
