We had a tech powere wash a unit and got some water up the tail pipe. could be water or condensation in the exhaust

serial number and/ engine size model might be nice to be sure we get the right info,
the mitsu 4g64/ 4g65 have been known to have a corrosion in the part of the cooling system that runs under the intake manifold. you may also have bad valve seals or rings.
are you loosing coolant or oil?