Truck overheats at highway speeds 2004 4.7

[justin32691]

Was driving today and while on the highway my truck started to run very hot so i pulled off to let cool popped the hood could see no leaks the reservoir was full to the max. i just recently had the water pump and belt changed and the top radiator hose so im not sure why its getting so hot. please help

 

[WilliamS]

Thermostat stuck half way. If it only does it at highway speeds its likely the thermostat is not allowing enough coolant to keep the engine chugging along. Does it do it at a stops or city driving?

 

[justin32691]

It started to cool down when i stoped but once i speed back up it get pretty hot again

 

[WilliamS]

It started to cool down when i stoped but once i speed back up it get pretty hot again

That to me rules out the water pump and fan as if it were the fan it would overheat at low speeds or stop not at highway. Water pump is working if its cooling it down, so all that is really left is the thermostat.

 

[justin32691]

Yea could be i put one in before i did the water pump it could be a faulty one im going to start the truck up to see if the fan kicks on to rule that out. could it be a clogged radiator?

 

[WilliamS]

If it were the fan or clogged radiator it would overheat while sitting still. This isnt the case. Im betting the farm on the thermostat has crap stuck in it. If any gasket, glue, or debris gets in there it can jam it up.

Its a cheap part that takes all of 20 minutes to change.

 

[justin32691]

Yea its most likely the thermostat fan is running it does overheat right away it takes like 30mins or so

 

[fastf]

It sounds like a thermostat but when you replaced the pump did you purge the air out of the system ? If you didn't you have a air in the system keeping it from circulate.This only a wild guess but if you replace the thermostat you got to purge the air out.Justin if it was stuck halfway open it shouldn't run hot now if it was closed you really got a problem if it was halfway open water would still be coming through it this is what I'm thinking.

 

[R.L.K.]

The lower radiator hose can get sucked completely shut when the pump is at higher RPMS , especially once up to operating temperature. These hoses get weak over time and sometimes the springs inside get crushed do to rough handling while changing the pump and such .

While the truck is up to temp and overheating next time , pull over ( put on gloves ) grap the hose and see if it compresses easily. Or if you have a passenger , watch the lower hose while they rev up the engine ...if it starts to suck in at all Change it .

Absolutely burp / bleed out ALL air from the coolant system . Just YouTube it if your not familiar ...many videos out there for this Very important procedure .

T-stats also are notorious for sticking with debris post coolant system maintenance such as a pump replacement .

Hope this helps !

Sent from my SM-G930V using Tapatalk

 

[fastf]

I just had a brain fart from a old fart how low a temperature do you have the coolant in your truck ? The reason I have seen antifreeze have ice crystals and make one run hot. If you don't have the antifreeze temp low enough to handle the weather you live in and what i see where you live you get really cold weather.That might be your trouble too.

 

[justin32691]

So i had a shop do the water pump and belt so i would hope they bled the air out. It was running fine after that because it was cold out its been 70 here last 2 days and thats when the overheating started again. i pulled over to let it cool this morning and the radiator was cool not hot so not sure what that means

 

[fastf]

Your thermostat is most likely the culprit .But when you replace it you are going to have to add antifreeze too.Make sure you get the coolant down way below zero.If you don't know how to purge the system it is real simple.Look at the top hose coming out of the engine there is a plug that you loosen and let the truck runs till you see all the air bubbes stop coming out of that hose also make sure you turn your heater on heat to get any air out of the heater core too .I hope this helps.

 

[ST-8]

My hemi had a similar problem, an ended up being the thermostat

 

[SYKRAMMAN]

When you bleed the coolant system, park the truck facing up hill a little bit if you can, it makes it easier. Your going to have to do it a few times and open the bleeder plug when the engine is cold only.

 

[fastf]

The thing about this forum if you don't know you can most likely get your answer in here to your problems.There is a bunch of good people in here.

 

[justin32691]

Happened again yesterday and I did check the bottom hose it wasn’t hot so most likely thermostat

 

[SYKRAMMAN]

Most definitely the stat!

 

[Ramit!]

Add some bg water coolant to your antifreeze. It will lower your operating tempature about 30 degrees. or go go to autuzone for waterwetter for antifreeze. the stuff works. drag racers use it to lhttps://www.amazon.com/Red-Line-80204-Water-Wetter/dp/B000CPI5ZK/ref=sr_1_1?ie=UTF8&qid=1519307583&sr=8-1&keywords=antifreeze+water+wetterower engine temps when antifreeze and electric waterpump can only do so much. every little bit helps or use waterwetter on amazon

 

[justin32691]

If it were the tstat wouldnt it overheat alot faster than 35 mins?

 

[WilliamS]

If it were the tstat wouldnt it overheat alot faster than 35 mins?

Depends on where its failed. Ive seen them fail shut, ive seen them fail open which is rare, but the most Ive seen in this situation is where something is stopping from opening completely.