Hey! Bears need NOM NOMS too lol!

 

It's at the dealer now,,,, hope its not the head gasket???? well we'll see what hopefully this time I can get an answer. Finally the check engine light came on hopefully then get a code??? Just want it delt with sick of playing guessing games.


It is now there overnight!!!!?????

 

There are a ton of things that can cause a 4.7 to run hot. You have already gone through the easy stuff.

From what I have read - the top hose was hot & bulged so you replaced it. If this hose was hot then coolant was flowing - which leads me to believe the thermostat was OK. Plus you paid a dealer to tell you the same thing. You may not like it - but they get paid to replace parts not tell you they are good - so if they didn't replace it - they didn't need to.

the 4.7 is a great engine - but it doesn't like to over heat & you can seriously damage the engine if it does.

Can you tell us what the oil pressure was doing? I test drove one (02 QC 4.7) that the oil pressure would drop as soon as the truck warmed up. Then the engine would slowly get hotter & hotter. It was a low mile truck but the PO drove the truck to a gas station after the lower hose blew & over heated the engine seriously damaging the cam bearings.

Now - the list of things it could be.
1) thermostat - already ruled that out
2) fan - already replaced
3) water pump - already had this checked
4) radiator could be gunked up - this is pretty common especially on older higher mileage trucks & any that someone used tap water in - as the hard water deposits will build up on the inside of the rad & plug it. How much heat does the heater put out? My 04 will literally melt the plastic ductwork & dash if I'm not careful. If your heater isn't putting out much heat - the heater core is gunked up & so more than likely your radiator is too.
5) Head gasket / cracked head - Honestly - you would know if this happened. These things dont wear out - there is an incident. The truck would run like crap & you would lose coolant. I'd guess you are OK here. But then I've not heard the truck run or seen it in person.
6) Cam bearings - these bearings wear out on very high mileage trucks & engines that have not been maintained - when they go - the truck will not keep oil pressure & will over heat from the inside out - total rebuild of the engine is the only fix - though you can limp it for a little bit with thickening oil addatives.
7) Believe it or not - there are a bunch of electrical issues that can cause overheating too - these happen because the computer puts in too much fuel or runs the timing off to such a degree that the heat is held in too long etc. Since the truck threw a code - you may get lucky & find a crank position sensor was bad & this is causing the ECM to change the timing.

Honestly - if it isn't the obvious - these things can be very hard to ferrit out.

Good luck with it & keep us up to date.

 

Hey all,
I just joined this thread because of this conversation. I drive a 2002 dodge dakota and it is doing this same thing and I cannot figure out why. The only thing I didn't see mentioned on here is that when the truck starts to heat up I usually turn on my heater full blast but whats werid is that while the truck is actually heating up(like when im sitting at a stoplight or at idle speed), the heater will blow cold air no matter what. Once the temp gauges reaches almost the red line it will reset or do something and start to cool off again, and this is when the heater goes back to blowing hot air again. I have changed the thermostat and flushed all the coolant lines. I have also changed the water pump. None of these worked and the truck is still overheating so I turned to you guys. Did you have any luck with figuring out what was wrong with your truck?

Thanks so much!

 

Mine did the same thing one day.. I put a 180 stat in, total system fluid flush.. (was dirty brown/green) and also found that my fan clutch is not working.. the fan spins.. but never really enages.. only when you run the truck cold does it engage.. but when the motor is hot never does.. something i have to replace..

JUST FYI..

 

I know you replaced the thermostat - but what you describe sounds exactly like a thermstat failure - It is very possible you have an air bubble getting caught behind the thermostat that is insulating it from the water temp. Only when the temp goes sky high does it open.

The major clue to the thermostat is the heater not blowing hot air. As you know it gets its heat from water circulating through the heater core. It doesn't circulate when the thermostat is closed.

An old timer trick to prevent this is to drill a very small hole in the thermostat before installing. This way if there is any air trapped it will pass through the hole. Coolant will too - but not so much as to cause an issue.

Of course - you could just have a bad thermo - I've seen plenty of them fail right out of the box.

 

Sounds like you need to burp it.
You could also have a clogged radiator.

 

Have you even tried to change it out? TO be quite honest with you.. I can tell you this.. if you can start moving (air is passing through the grille cooling the Rad's liquids.. ) your coolant system is working.. You could have a partially clogged radiator not allowing enough cooling to occur by just the fan it self.. as no liquid is pulling through..

Or you could have clogged, damanged/bent fins on the rad.. check them... if air cant pass through the fins.. it cant cool down the liquids inside..

My number one suspect would be the Fan clutch and or clogged RAD somewhere inside and you should flush the system with some flush.. really good..

Also, make sure your fan shroud is intact as missing this the fan can not pull air through correctly or in the same volume and your cooling eff. is reduced greatly..

The problems your facing are real simple.. if the thermostat was stuck closed.. it would not allow the system to cool off once you started moving.. so your problem is either lack of air flowing through the fins of the RAD-- Clogged fins and needs a little soap and water and fine brush to clear and clean, this also includes the AC one before the RAD, and the small Tranny coolant if you have one inbetween.... or the fan shroud.. or the fan clutch is not working or not the correct one.. so on.. so forth..

or..

the problem is with the ability to actually cool enough volume with the currect amount of air passing through to be reduced by some clogged areas of the Rad internally.. and you would just need to flush the system really good..


And lastly Dont use a 180 stat.. its only masking the problem.. just as I seen, temps would raise but only to normal op temps..
(Also your sensors will be in a contentious open loop)

 

Watch the coolant and radiator levels if they drop while its not cranked take the spark plugs out and turn it over. If water sprays its the head gasket

 

Gents,

I have am experiencing the same problem as the original post. Several service techs have looked at it; which are my cousin, two personal friends and the techs at the repair shop which work on my vehicles. They are all stumped.

I have replaced all of the following parts;

radiator fan
condenser fan
radiator cap
water pump
thermostat
coolant temperature sensor
new coolant

The initial problem started about a month ago. The AC did not cool efficiently. At idle the AC would warm up, i.e., stopped at a traffic light, but when driving the AC would cool. My cousin noticed it and immediately identified the problem. Radiator fan clutch was out and the condenser fan would not start up. I replaced them. No overheating problems.

(SIDE NOTE***: The ac compressor was damaged due to the faulty condenser fan so I ordered a new ac kit but have not installed due to the overheating problem).

Two weeks ago, I found a pool of antifreeze on pavement. I started the truck but the leak was sufficient that there was a continuous drip of antifreeze. So parked the truck and ordered a new radiator. Put the new radiator in and that's when the overheating started. There is good flow through the radiator but there is one odd or interesting thing when the truck heats up; the radiator tank on the out port side of the water pump never heats up even though the upper radiator hose does. The tank stays a ambient temperature. However, the tank connected to the lower radiator hose (thermostat side) does heat up. And when the heat is turned on inside the cab, there is a continuous flow of hot air.

The system was pressure tested and at idle the pressure is 13 to 14 pounds. When the engine is rev'd up the pressure climbs to 16 to 18 pounds but never higher. And the pressure climbs gradually as the truck warms up.

The system has been bled (burped) several times. However when the system is bled it still generates a lot of vapor / steam.

The truck idles and accelerates great. It does not miss or sputter. Also, no water in the engine or transmission oil.

I'm hoping that the expertise / experience found in this forum can help me? Any ideas besides what has already been posted?

Thanks in advance for you comments / suggestions!

Regards,

bzp