I've been fighting this for months. Let me break it down:

2 yrs ago replaced water pump and t-stat (replaced with 180*) on side of road (broke down).
Fine for 1.75 yrs.

Last few months:
Once engine gets to operating temps, if I drive over 70mph, the temp gauge will jump up to 240ish, hang there for less than a min, then drop to 205-210*. Why it doesn't drop to 180*, I don't know. If its a warm day, staying under 70 mph, it will do this every few miles. If I drive over 70mph, it jumps up every few minutes to 240ish, then to 210, then back to 240, then back to 210 and so, but stays closer to 240 for a longer period of time.

I replaced the water pump today, since it had a lifetime warranty, but still having same issues. I'll have to buy a new t-stat, and try that next.

Also, before the temp gauge starts to jump, the engine compartment sounds like an 18 wheeler intake, super loud, like its sucking in more air. This sound stays around longer than the temp gauge fluctuating.

A buddy said I might have a leak in a heater hose, but I hooked up a pressure test pump to the radiator cap a few months back, pumped her to 15-16psi, and it stayed at that psi for 10 or so mins.

Im stumped.

Many thanks.

Btw, I have the following codes, but I don't think they have anything to do with my current prob. Cleared them many times with the Smarty jr, but they still come back.

PP016c
P0016
P0542


(Its an 07.5, aka the Code Thrower)

Im more worried about my coolant/ temp issue

 

Sounds to me like the coolant system wasn't burped properly and you still have an air bubble in the upper hose.
Back to morning brew . . .

 

So how does one properly burp all the air out of the coolant system. Yesterday when I replaced the water pump, I flushed the coolant system also. Driven it 20 or so miles and need to top off the rest since it got up to operating temps and radiator is now a touch low.

 

There is a coolant bleed valve above the EGR cooler...
Possible the thermostat is sticking shut and the noise you hear is the clutch fan since it is smoking hot?

 

Steamin, not saying this is your problem, but...
Few years ago I replaced my generic Quadzilla "all in one" sensor gadget and went with stand alone gauges. This mod involved me disconnecting the Quadzilla temp sensor. I didn't do a very good job of disconnecting/clean-up... Immediately after the mod/work I took it for a drive and soon noticed the temp gauge fluctuating wildly (from normal to max overheat). I had my code-checker with me and the scan showed a faulty TEMP SENOR (i forget the exact code). I was near an autozone, so I ran it and got a replacement -- but I didn't look under the hood first. When I opened the hood to start the replacement work, I noticed I had left part of the old Quadzilla sensor wire dangling...it had melted against the HOT engine, which I surmise was generating the wild errors and code. I removed the offending wire, taped it out of the way. I easily replaced the sensor regardless. All fixed; never an issue afterwards. This was on my 2001.
Again, not saying that's your problem, but providing for info just in case. D