Need help. My buddy has a 2005 f350 and just recently had an egr block and head studs done by a ford diesel tech. The truck is now running hot with the thermostat in but with thermostat out it is only getting luke warm. Not even hitting running temp. After the truck gets hot with the thermostat in top radiator hose has no pressure in it. It is soft to the touch and is not leaking coolant anywhere. The truck only has 40000 miles on it. Wondering if might be a sensor or possibly the water pump. Just put a brand new thermostat in thinking it was that but didnt fix anything.

 

Did you disconnect the EGR? The fan needs the EGR valve connected to operate correctly.

Josh

 

the truck fan will come on when it gets hot enough it is custom sct tuned and the egr system is not a part of it anymore. i just cant figure out how it would not come to temp with thermostat out and get hot with new thermostat in. the cooling system has no pressure at all in it even after truck is hot and then turned off no pressure top hose is warm but you can squeeze it together with two fingers. could a cracked impeller on water pump work kinda intermitten like this? also no mix of coolant or oil no levels are changing at all nothing coming out tailpipe so i belive all the work that was done is correct.

 

Did he use a factory t-stat? I have gotten more than one new faulty t-stat over the years. As important a job as they do they, esp. a/m, are about the cheapest part made for all vehicles.

 

My first question would be what are you using to read the temperature? The indash gauge or a scanner of some type? Like 69cj, if you didn't use a motorcraft thermostat then I urge you to purchase one and try it.

 

Shot in the dark: no pressure could indicate a faulty or improperly installed degas bottle cap.

With no pressure in the system, spot-boiling could be creating vapor locks and/or hot-spotting near the temperature sensor.

The caps are cheap and easy to fix/replace. Try that first.

A cracked/broken impeller could also cause these symptoms, but if the water pump wasn't disturbed during the aforementioned work, there's no reason why it would have broken, and a coincidental failure is rare, from what I understand.

-blaine

 

I tried two new therms. It did not change anything I took it to ford and had the system pressure checked it was fine no loss of pressure. Am in process of changing water pump now. Temperature check was with auto enginuity and then with heat gun and they agreed with truck gauge also changed temp sending unit and again no change.

 

AE I would trust. Dash gauge is nothing but a cold/normal/hot idiot light with a needle. While you're changing the water pump check the front cover for the slightest amount of wear or scaring. These can cause bypass/overheat issues from lack of flow. It really really doesn't take much.

 

In a properly working system the pressure in the degas bottle is a function of expansion. Pressure may be a little higher on the output side of the pump but there is a equal reduction of pressure on the input side. By the time you measure at the degas bottle these pressure have balanced out. As the coolant expands, it will make pressure in the system if it is airtight. If it has no pressure, there is a leak. The only way this could not be true is if the system pulls a vacuum as it cools and warms back up to 0psi.

 

Ok first I would like to tell everyone thanks for your help. So after changing the water pump you guessed it no change ford master tech could not figure it out either and wanted to tear apart motor after it had already been gone thru. So I took it to clay from riff raff he is the one helping me and it didn't take him long to figure it out the radiator which is the last piece of the puzzle and was brand new from ford is not flowing thru luckily they are sending another new one so in the end I assumed and overlooked the radiator because it was new and the ford dealer got me for $730. Lesson learned don't assume s--t thanks again.

 

Damn... new radiator was junk? How does THAT even happen?

Josh