overheating
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overheating
new to forum I have a 99 f150 super cab 5.4 truck overheats at low or idle speed but not on highway I have replaced thermastate, heater core, water pump, rad cap and flushed entire cooling system 3 times. this all happen very suddenly, I've owen truck for 3 yrs and temp has always run same place on gauge till recently. Truck has 260000 miles, with the overheating problem I have no smoke no loss of power no water in oil
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i have also replaced fan clutch and it still pushes antifreeze out of bottle my rad dose not have a cap a friend told me to take old thermastate and remove center and install outer ring of thermstate in motor and it runs at normal temp or just above normal with ac on
Posting Guru
Joined: Oct 2008
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From: Hernando Ms
I would replace the Thermostat with a good BRAND name one.STANT comes to mind immediately,but Im sure some others are just as good.Stay away from AUTOZONE.
Typically NAPA,or O,Reileys carry reliable parts.Im in the Memphis Tennessee area,and you may not have an O,Reileys where you are.
The fact that evidently you are "cooling" at driving speeds tells me that the radiator is basically doing its job,my first suggestion would have been fan clutch,but you say it has been changed also.
Bottom line here is it sounds as if you have little to no air passing through the radiator at a dead stop.Thermostat typically wont be the cause of this condition,but it could still be defective.
Typically NAPA,or O,Reileys carry reliable parts.Im in the Memphis Tennessee area,and you may not have an O,Reileys where you are.
The fact that evidently you are "cooling" at driving speeds tells me that the radiator is basically doing its job,my first suggestion would have been fan clutch,but you say it has been changed also.
Bottom line here is it sounds as if you have little to no air passing through the radiator at a dead stop.Thermostat typically wont be the cause of this condition,but it could still be defective.
Fleet Mechanic
Joined: Sep 2003
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Two thoughts, both easy.
Lower radiator hose walls sucking inward at highway engine RPM due to softening hose if the original was a rigid hose. Or a replacement hose was a thinner hose that should have had an internal coil spring inside to prevent collapse, but the spring is missing.
With truck good and hot first, could have someone bring engine RPM up to 2-3,000 RPM in Park while you look at hose from under the front corner of the truck, see if it sucks in anywhere.
Second idea... get Carbon Monoxide test strips from parts place, and test antifreeze while running to see if CO is showing up in cooling system. May have to rev it, though a non-loaded 2,000 RPM isn't the same as an engine under load on the highway, but may show up something you don't want to see after all.
Lower radiator hose walls sucking inward at highway engine RPM due to softening hose if the original was a rigid hose. Or a replacement hose was a thinner hose that should have had an internal coil spring inside to prevent collapse, but the spring is missing.
With truck good and hot first, could have someone bring engine RPM up to 2-3,000 RPM in Park while you look at hose from under the front corner of the truck, see if it sucks in anywhere.
Second idea... get Carbon Monoxide test strips from parts place, and test antifreeze while running to see if CO is showing up in cooling system. May have to rev it, though a non-loaded 2,000 RPM isn't the same as an engine under load on the highway, but may show up something you don't want to see after all.
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thanks for all the input from everyone. I drove truck this evening in town and on highway temp outside was 90 and truck run about normal with no antifreez coming from degas bottle and also believe it may be bad thermastate. I removed the new one and like i posted earlier cut the center out of old one just the outside rim like the thermastate would run open all the time but with some restriction. im going to drive it like that for 1 more day then install another new thermastate if it dosent get hot or puke more antifreeze. 1st replacement thermastate was from advance auto. Get next one somwhere else. I live in west virginia and have alot of hills to drive up and down. I will post what happens tomorrow after work. And thanks again for all input I was running out of things in cooling system to replace cause i forgot that i also replaced belt and belt tensioner.
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I would agree with torky2...But first off, I'd put a new thermostat in (running the engine with no thermostat or a modified thermostat could result in a damaged engine in the long run).
As mentioned by others, check the lower radiator hose and the condition of the radiator. I'll bet if you replaced both your problem would be solved. My old ranger showed similar signs and a new radiator and lower hose solved the problem.
As mentioned by others, check the lower radiator hose and the condition of the radiator. I'll bet if you replaced both your problem would be solved. My old ranger showed similar signs and a new radiator and lower hose solved the problem.
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Well i drove to work today and it didnt get hot but on the qay home 1/2 way back temp when up slowly till it got about 3/4 way up and then with in 5 seconds it went all the to the h cooled off refilled and went about 1 mile and did the same thing so i had it towed to my dads we looked in degas bottle and it looked like sand in bottom so im relpacing last pc of cooling system the rad still no smoke loss of power or bubbles in degas bottle holding plenty of pressure so im hoping the rad fixes it
Hotshot
Joined: Jul 2005
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jumping to H and back donw quickly means air in the system. Either you dont have it purged and have air trapped in the coolant lines, or you have a small head gasket leak and it is pumping a small amount of flue gas into the coolant, overpressure, and blows it out the cap.
Hotshot
Joined: Jul 2005
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if you are sure the radiator is FULL and it keeps doing it, try this
Bar's Leaks Liquid Copper Block Sealer
Bar's Leaks Liquid Copper Block Sealer
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i had that same problem with my V6 and it was the famos sand in the radiator problem. I also changed the water pump and thermo top and bottom hoses and flushed the system and tank. After all that it ran better than it ever has before
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well i got new rad and top and bottom hose and installed new stant thermastate this evening also flushed all new old antifreeze with waterhose and we got stuff that looked like sand dirt and gravel out of old rad and while trying to get more out to see what else was in old rad water would not go through it very fast so cut it in half and top and bottom 6 or 7 rows were pretty full of what we got out with water and the rest was startin to look like it was startin in the rest of the cores Temp was about 96 today im actually suprised it didnt get hot last winter on the coldest day the way rad looked all was good tonight well see tomorrow its suppose to be just as hot i just hope its fixed i do believe i will change antifreeze in a week to see if anything comes out of motor and heater core. Nothing else in cooling system that is not old
Postmaster
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On my vans, the only thermostat I have had good results with was Motorcraft. Sorry, but the Stants just don't hold up and are not speced properly. My problems haven't been overheating though, they would always overcool.
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well i went to work which is about 45 miles this morning and truck run at normal temp just like it did last night but when i left work i drove about 4 miles truck was normal then within the next 2 miles temp began to rise so i shut truck off and raised hood and it was pukin out more antifreeze out of bottle so i slowly released new rad cap to let pressure off and when it was completly released took cap off and antifreeze sucked back into motor and it cooled back to normal and drove the rest of the way home and had no overheating problems on interstate driving 70 mph when i got home set in garage for 1/2 hr with truck idling and ac on max and still no overheating problem cant figure it out. Which line do you fill to when cold on degas bottle Ive been filling to just under top line but I think i will not add any more antifreeze since when i got back home and running in garage with ac on and leval was just below bottom line im hopein i just had a air bubble stuck and to much antifreeze any input might be helpfull if anyone has any ideas please post and thanks again
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