'03 GTI cooling problem
 

Hi everybody, new to the forum. Got a problem with my GTI. I had to replace the water flange because it developed a split and now with the system refilled the engine doesn't seem to want to flow the coolant through the engine. When it's running and warmed up it will maintain normal temp but if you put the cap on and either drive or let it sit and idle it starts to heat up. Take the cap off and the temp will go back down to normal after it lets out a little water and steam. When it's warmed up the lower radiator hose stays cool. I replaced the thermostat and tested the old one which is still good but the problem remains. When I refilled the system I used G-05 coolant. I know now that's the wrong stuff, it's supposed to be the G-12 type. So here's my question: did the wrong coolant react with the remaining coolant and create a blockage in the system, or did the water pump take a crap just by coincidence. Looking forward to any suggestions.

sorry,i can;t help you