What are all possible reasons for which car has tendency to go almost up to H for "Hot"?

And here is another photo....

The problem you have is the cooling system is not purged from the air pockets. In the picture above, the coolant hose is on the left, and that looks like a plastic tube for something right in front. Coolant hose does not look bad from here but may want to have someone look to be sure. Here is how to purge the cooling system... www.youtube.com/watch?v=zUpXgAJ1gjU

If that tube in front above is rubbery, it shouldn't be like that. Have someone look at that, hard to tell from here.

The hose in this photo now is a little rubbery.. but no more or no less than other houses just like it - it just looks a little swollen up at that end that goes into the engine.. So just because there's some air into the coolant system can cause the engine to be a little hotter than normal? In the video you linked Eric is talking about the bleeder valve - do I really need to find that and loosen it out because I don't know where it is on the my car ... can I skip that step ? Thank you for answering so fast ....

This photo .....

Being a 2004 the radiator hoses and thermostat should be changed out as tennesshoes is saying. That is an original clamp on that hose, and if it were ever changed out before, mechanics like to use the screw type hose clamp. A old hose can pop at any time. Might as well do this right. And what they don't show in the video is that it helps to raise the front end of the car when purging as air bubbles float upward, even have it on an incline of some sort.

So I will need to purge out the air but I will need to top off the coolant for that... Should I use the same type of anti-freeze concentrated that I used to actually fill in the cooling system after the flush or I can use the cheaper topping off type coolant ?

And here is how the hose looks when the car is all cool and there's no pressure ... it looks a lot less bumped out? doesn't it? Thank you....

Ok, hoses should be changed. Use 50/50 mix when filling the cooling system. Not the straight concentrate.

I did a purge, not the hose or the thermostat (I had ordered them but didn't arrive at the time)... I will do those as well but in the mean time after the purge I noticed that the temperature fluctuations were a lot reduced but still present... Also Check engine light came on >> code was P0121 TPS > Throttle Position Sensor >> MY QUESTION IS: Is there anyway the TPS can affect the temperature / heating and cause the engine to run at a higher temperature than normal?

No, but the TPS needs to be looked into before it starts having bigger problems. It affects acceleration, idling, and can cause a reduced engine power.

Replacing it is just as easy as taking the old one out and put the new one in, correct? No codes or special tune up or configuration that needs to be done, right? I'm gonna order this for $23: https://www.amazon.com/dp/B004HO1L2Q /ref=cm_sw_r_cp_api_z-b7yb748PS4K Looks ok?

On any sensor, the wiring should be checked from the plugin back into the wire. A lot of times a wire will break under the insulation. This is a 2004 so I wouldn't feel so bad in replacing this, because there are little fingers so to speak that get frayed in the TPS that run across a rheostat that do wear.

So last night I replaced the thermostat and just the upper radiator hose (put new screw- on clamps), replaced the TPS as well and GUESS WHAT I noticed while cleaning the thermostat housing - it frigging has a while in it about 1 mm - all very likely from the too high a temperature. So I will get one from PepBoys tonight BUT the question IS: what was causing my car to run so hot that in time it dug through the Metal housing of the thermostat?

And here is another photo of the hole in close up...

Could that little hole cause fluctuations in the temperature?

I bet the water pump would need changing, I can just imagine what the water pump impeller looks like.

Do I have to remove the timing belt before I can replace the water pump ? Is replacing the water pump pretty hard to do ? And thirdly what caused all of this (before the hole in the thermostat casing) heating...?

The timing belt does not drive the water pump, but looks like it is in the way for water pump removal. So the timing belt would come off. The thing is here is you might as well replace the timing belt and idler pulleys, and belt tensioner since it is apart. You would want to line up the timing marks first before removing the timing belt. It is not like this job is hard but it has to be done right! This is a big job. And the cause for this is neglect to the cooling system, not being serviced, flushed and new coolant put back in. Also I would have the coolant tested for carbons that indicate a bad head gasket first before putting this time and money into it. Shops have this kind of test, I am not sure how it is done. Tennisshoes may know, he has a good head on his shoulders and you would want his input on this also.

65,300...

I concur with tennisshoes.

Are you saying that if it was good at 40k than it may be worh to do the serious work? Also once I will replace the thermostat housing it is possible all my problems are resolved BUT I am pretty sure that the coolant level will be VERY low so I will need to refill > should I use the concentrate and then will purging refill with 50/50 or should I just use the 50/50 all the way?

So I put in the new thermostat housing turned on the engine after I topped off the coolant then let the engine run until it reached normal operating temperature then reved a few times, the coolant temperature reached 197, and then short few minutes after that the engine died on its own. I tried to start it again and it just seemed like it was coughing and Couldn't start it again. I checked the oil cap and it looks like in the picture..does that mean I have water in the engine now and It's busted and I need to have major service on it?

And now I'm getting all of these code then never showed up until tonight ...P0300 / P0303 / P1586 / P0304... I don't even know if it's worth for me investing another probably at least $1000 in fixing the engine - it really seems like that's what it is !?! P0300 - Random multiple misfire P0303 - misfire on cylinder three P0304 - misfire on cylinder 4 P1586 - Pertaining to the engine control module

Is it possible that because of the hole in the thermostat housing and even though i plugged it with a thin metal wire because i drove the car like that, is it possible that some air, condensation and coolant got inside the engine block and that's why is now getting hot? Can a simple engine flush fix it for me?

http://www.blocktester.com/instructions.ht m Would that be able to test the block or car needs top be in an actual mechanic shop for proper testing?

So I guess it's kind of clear that I have a blown head gasket: heating up, cooling fluid level drops without clear signs of leaks, White milky stuff at the bottom of the oil cap, coolant in the radiator jumps out / raises a lot while accelerating with the radiator cap open, rough idle to the point where engine stops, P0300, P0303, P0304 diagnostic codes. I think that's most if not all of the signs for a blown gasket. Agreed? So I think I'm going to embark in the adventure of replacing it all by myself well I'm going to take the bike to work. BUT, once I have the cylinder head and the engine block out of the car, where can I go to have them pressure tested and surface leveled? I called the actual dealership and they said they don't do that kind of stuff, I called some mechanic shops and they said they don't do that kind of stuff....

You may be better off finding a different engine out of a junk yard.

How come better ? Isn't there a big risk of getting one that is for sure cracked (that's why it's in a junk yard) ?

For that car, it is just my opinion. Your going to have a lot of time and money into this. And I guess your right on finding one in a junk yard, but where I am at, you can get an engine the junk yard would warranty for 30-60 days, you'd know if the motor was bad during that time. I'm also just holding my tongue because I don't care for Kias.

I'm willing to put my time in doing it as long as it's just the gasket (i'll take the cylinder head to the shop and have it resurfaced) But is there any other way of testing the block for cracks other then taking it out and then to a shop for pressure testing?