Engine running hot

My friend has a 91 Beretta. It has a 3.1 L engine. The engine is running hot almost to the point of over heating. He removed the thermostat by passed the electric fan so it runs all the time. He also took it to a mechanic who ran an emissions test. Showed High Hydrocarbons told my friend it was a blowed head gasket. I found a bad water pump but still running hot. I wanted to pressure test the system. He's being harded about the blown head gasket. Mechanic said hot exhaust gas is leaking through gasket super heating the coolant?????

My question would a bad cat convertor cause the over heating? That would also explain the high hydrocarbon reading?

I would ask is the car loosing coolant? What happens to the hoses when the car heats up? Do they swell badly? A plugged converter can cause overheating, yes. A blown head gasket can do some bad things as well. My dad's old 89 Olds had a cracked head and blown gasket, and it leaked coolant into oil (check for this too...) and built up terrible pressure in coolant system, as the leak blew pressure right into water jacket. I would suppose either of you could be right, but check for - oil in coolant, see if leaking coolant, any oil in coolant, swelled hoses, and, if possible maybe the best test would be to check compression in each cylinder, to see if a cylinder has very low pressure. Your guy might be right, but you never know. Normally there is some kind if leakage as far as fluids are concerned. But let's see what others think here as well.

No there's no sign of oil in coolant or coolant in oil. No excessive pressure in coolant system. It doesn't appear to be loosing coolant. Pressure test on coolant system will prove if leak exists. Not my mechanic I do all my own work.

You probably fixed it when you replaced the water pump, and the lack of a thermostat is a new reason for it to run hot or overheat. The coolant has to stay inside the radiator long enough for the cooling fan to do its job, and without a thermostat the fan will not have long enough to cool the water back down before it goes back into the motor. Try and locate a 180 thermostat to put in place of the original. Im guessing it calls for a 195.