fan running hard cant find issue

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chocolat1701

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during the last 6 months i have replaced all the cooling components of my 04 v8, this is what i have replaced upper and lower radiator hose, radiator,water pump,degas bottle, thermestat housing, thermestat, thermestat cover, thermestat housing neck (this goes to the engine), the dccv was replaced over 2 years ago and now the car is not leaking we did a preasure test and its holding, i bleeded the system several times and the fan turns on and blowes hard but the temp gauge does not go up, if i turn on the heat to 90 the fan stops and all is normal and the heat comes out hot. if i turn on the ac and set it to 75 it the fan gradually turns on and goes to high, we checking it with a scan tool and the engine temp goes to 228 and when we turn on the heat it goes down to 218/220. now we also was scanning with the ac on and driving in highway speed and the temp went down to normal and fan turned off. also after checking the lower hose is cool to the touch and the upper is hot. i think we checked eaverything and cant find the issue. the only thing i can think of is that i added prestone stop leak and it maybe clogging something up. now i was thinking if the dccv is clogged will this couse this its the only thing that i can think off. NEED HELP
 
No, just having the DCCV clogged will not cause overheating. Maybe it is time to have the cooling system very aggressively flushed. It could be the stop-leak. Beyond that, are you 100% certain that you have the correct water pump? If the vanes on it are pointed the wrong way, it will pump very little water and could be the issue. I am assuming that the thermostat is correctly installed. If in doubt, you could try removing it temporarily as a test.
 
i did that i removed the thermostat and just ran it that way and same issue, i replaced the waterpump last while i was having the issue since that was the only thing at the time that i did not replace and i was thinking to that the plastic fins was broken since i have 133k on it and its still the original. now we inspected all the hoses and they dont seemed clogged unless the stop leak clogged something in the engine, my mechanic was saying that the flow was slow when we was running the car with the degas cap off and the engine fill off without the thermostat in the housing so we can see how it flows and he said it was slow compared to other cars. but like i said the fan turns off when i turn on the heater full blast and even though i turn on the ac and the fan turns on the temp gauge does not go up at all. could it be a foulty temp sensor maybe. the car did overheat a couple times already.
 
So, there's two differences between the heater core (small radiator) and the radiator (big radiator).

1. Coolant is pumped through the radiator by the water pump. Coolant is pumped through the heater core by the aux pump.

2. Air is pulled through the radiator by the engine fan or by motion of the car. Air is pushed through the heater core by the AC blower.

You know that you can cool the engine via the heater core, and you know that the engine isn't cooling well enough via the radiator alone. Either enough air isn't flowing through the radiator, or enough water isn't flowing through the radiator.

Check for dirt between the AC condenser and the radiator that would impede airflow.
I would wonder if the stop-leak is obstructing water flow though the radiator. Do you have a spare radiator that you can try?

I'm going to guess that the radiator is clogged (coolant wise) because you said the lower hose was cool. If it was an airflow problem, the lower hose would be hot.
 
the reason that i put some stop leak is that my radiator busted so i needed some time to take it home, so the radiator is new as of 2 days ago and thats when we noticed the problem. so that day we changed the radiator, thermostat and housing and water pump the same day. and we flushed the system before we installed it to try to get the junk out.
 
chocolat1701 said:
the reason that i put some stop leak is that my radiator busted so i needed some time to take it home, so the radiator is new as of 2 days ago and thats when we noticed the problem. so that day we changed the radiator, thermostat and housing and water pump the same day. and we flushed the system before we installed it to try to get the junk out.
Click to expand...

Well, I'm out of ideas.
 
Don't know if it'll help, but my gen 1 lincoln had been overheating for a while. Fan kicked on so hard it sounded like it could take flight, no leaks were apperent in the cooling system either. oddly it only overheated in traffic. not in park or at highway speeds. couldnt make sense of it until my dad pointed out the idle was rather high. Idle air control valve was gummed up and running at around 1400rpms at an idle. was overworking the engine and tranny.

i probably sound goofy for missing the idle, but i just bought it used and that's how it had always been. along with all the other issues i'm weeding out one by one. at least she's beautiful right?
 
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