Ok this will take some explaining because nothing I have can ever be simple.


For the past week, my truck has overheated every morning. Not to a dangerous level but its ran hotter than ever before. (and I have cruised on 100 degree nights with the air conditioner on)


For the past 5 mornings I have got in the truck and turned the defroster on low and took off to work. I get about a mile from the house and the truck will be at its normal temp. but a few miles down the road it will slowly start creeping up hotter. So then I will turn the heater up to high and the truck will start to cool back down. Once its back to its normal temp. I will shut the heater off and its fine till I get work. (this is all highway driving when its over heating @ 60mph)

In the afternoons I drive thru stop and go gridlock with the air on and then head home on the highway @ 60mph and it runs at its normal temp.


In a fit of confusion yesterday I replaced the termostat since it was cheap insurance but alas this morning the same scenerio played out again. Any ideas?

get rid of the antifreeze and put str8 water in there and see if it runs better? i have water in mine right now, although i eventually plan to put antifreeze back in there for the winter

if you do put just water in it, which i dont recommend, use distilled water.

Try flushing the radiator out, you might have some build up in the radiator restricting flow. i know my truck would heat up a lil bit but once the thermostat would pop, it would fall down to running temp and stay there. when i flushed it out my radiator, all kinds of stuff came out.

I agree...flush the radiator out & I use 1/2 distilled water & coolant in my truck & my eclipse. A little trick my dad showed was to take the plug out the bottom of the radiator, place the hose in the top & while the truck is running allow the water to flow through flushing everything out real good. Hope all this info helps!!

never use just water, lol, water rusts, you dont want that and yes distilled water if any, 1/2 and 1/2 is best, mine did similar to that and i replaced everything except the radiator and it still did it, i got a rad online for 70 shipped and never had the problem again, my rad looked like it flowed nicely too when i tested it oh well, its fixed and not mine anymore.

its just a run for the winter, not mention, in essence, water is better than antifreeze is waaaay better in cooling than antifreeze is, which i have been able to attest to personally. my truck hasnt run this cool since i changed out my thermostat. it was always at 1/2 way mark, now its at the 1/4 mark constant, even in teh dead heat. antifreeze is for...anti freezing lol. thats why im switchin when winter gets here

no not really, lol went to school for this, water doesnt cool as quickly, by any means, check the boiling point on either, also if anything wetter than water is better than anything for a coolant..

dude, phatboislim is right straight water will keep your engine cooler then 50/50 because antifreeze retains heat most race cars run water and a wetter like purple ice because it even lowers operating temps that much more although it isnt a long term fix you could have a bad thermostat bad head gasket ive seen the impellors break off inside the water pumps radiator could be clogged either in water flow or debris in the cooling fins restricting airflow also straight water without antifreeze/coolant causes electrolysis which is like static electricity which is conducted through the water and gererated by turbulance which causes pitting and corrosion of your block and heads and the boiling point dosent have anything to do with cooling cause it shouldnt get that hot if everything is working right

ok, quick reply.

water will blow your hear gasket. PERIOD.

How does the old idiot know?? I DID IT.

Water will RUST the metal crimp sleeves in the head gasket. Once the sleeves rust through, all thats there to fight the compression of the engine is generic old gasket material, which WILL blow out, sending water STRAIGHT into the cylinder.

dont be stupid.

anyone notice its really called ANTIFREEZE/COOLANT??

do things the right way-- flush your engine, radiator, change the thermostat, and fill it with COOLANT.

Allright I have another thing for you to check, are you still running the original cooling fan? if you are, its a thermostatically contolled clutch. The fan clutch is made to be tight when hot air is passing by. When cooler air is passing by, it disengages sort of, to reduce the load on the engine by letting the fan not spin at the same speed as the enging. The fan clutch engages to make the fan turn faster when the engine needs extra cooling, like on hot days or when idling at a light on a hot day.

im not saying run water forever i dont recommend that at all. the reason antifreeze is mainly made is not only for 'not freezing' but also no rust..its a lubricant it has a 'greasy film/feel' if you will to it. im just saying run water and see how it will run..if itll run cooler for u. personally...this is the coolest my truck has run....EVER. even before i put a higher degree thermostat in, it never ran this cool via temp gauge.



you mean a 50/50 mixture at least right?? its not recommended to run straight coolant

well, yes, thats what i meant, but you may notice 70% of coolant you buy these days is already a 50 / 50 mix.

yea but i mix my own ill put most of the coolant in the radiator.. and pour the rest in the over fill tank. then top the rest off with water.


I NEED TO KNOW WHERE(if we have one) the coolant bolt is on our block. im about to flush my coolant system today

back left. down from #4 plug.

Running straight coolant or straight water is bad either way. Water will run cooler yes, but if you do by chance overheat the water evaporates at a much lower temperature. Mixed with coolant, and the pressure of the cooling system will keep the boiling point higher. 50/50 is your best bet, regardless. And you don't actually want your truck to run too cool, its not good for its components. That mid range on the gauge is between 180 and 200 degrees, this is where you want your truck to run. Colder is not always better. A little hotter is fine, and some vehicles get better mileage when they run slightly hotter. I like the 180 thermostat, because it keeps it at a comfortable ranger. But on the way to Drop Zone I ran the 195 thermostat, and averaged 30 MPG, even with the grades.