back pressure is normal under operating conditions as to what pressure cap is fitted on your vehicle.
if the pressure is excessive and forcing the water out of the overfow get a gas leakage test done to determine if the head gasket has gone or other problems are there mostly combustion heat and pressure in the water jacket of engine. also check for faulty thermostat
paul dwyer, July 2012
on a ???????? as my crystal ball is not working any idea how i can fix it ,then i can fix your vehicle ,which you not given any details off ,ie make model year,just some of the important things
