07 4.6 cooling/overheating issues - UPDATED

[owner66]

I had the same symptom, fan roaring even on highway, sudden overheat, outside temp above 83 or so, heat soaked. Replaced fan clutch, water pump, thermostat, radiator. Same overheat issue. Finally replaced CHT temperature sensor and put OE thermostat. Problem solved. Not even entirely sure it was actually overheating but instead the sensor was making ecu think it was overheating. also, no codes, and temp gauge acted kind of jerky when going from overhear back to normal. Sensor is easy to replace on the 4.6 , take off alternator, look in valley, it’s back on the left. 19mm wrench loosen it to spin it around if you can’t get connector off.

 

[ThunderbirdSport]

Mine does this as well, has done it since I bought it March '19.

I too replaced clutch, w/p, t-stat, and the rad was new when I got it. I also had to put in a fan shroud as some dumb-as-**** previous owner took it out for whatever reason (probably when rad was changed) and didn't want to fight to get it back in. Well, I'll tell ya, it ain't too awful much fun putting one in, but I've certainly done worse automotive jobs.

I also replaced the CHT and the t-stat again with what I think was a 16 pounder, may actually be less, can't recall.

The issue persists.

I wonder....would a motorcraft CHT sensor be better than a part store house brand? Both times I swapped the CHT was from oreilly the first time, car quest the second.

At this point, the issue isn't really much of an issue as I barely drive it now that I have my Expedition. Would be nice to have it in case something happens to the big boy though...

Never thought about removing the alt to get the CHT out. In any case, pulling the intake to me wasn't that big of a deal, but probably takes longer than moving the alt and going in that way...

 

[94Eddie]

I just want to add a quick note here about using a 16 psi radiator cap instead of the stock 20 psi cap. My 2007 Mustang GT has the same 4.6L 3V engine as the 4th gen V8 Explorers/Mountaineers. It appears the radiators are the same with a few minor differences. The cooling system for the Mustang uses a 16 psi reservoir cap and the cooling system has to be robust enough for prolonged high speed/high revving/high engine load use which probably isn't much different than a 4th gen V8 when towing etc. IMO, this probably supports that using a 16 psi cap in place of a 20 psi cap will have little to no negative side effects on cooling ability for a 4th gen V8 or V6 Explorer/Mountaineer.

 

[MNgopher]

I'm not going to advocate whether using a 16 psi cap is a good idea or not. I will point out that just comparing the radiator in the Mustang vs the radiator in the Explorer isn't as simple as just saying one works with the 16 psi so the other should too...

Recognize the Radiator in the Explorer is a downflow radiator. The radiator in the Mustang is a crossflow. Downflow radiators traditionally take a a higher pressure cap to function correctly as the cap is located at the highest heat, highest pressure part of the system.

 

[94Eddie]

I'm not going to advocate whether using a 16 psi cap is a good idea or not. I will point out that just comparing the radiator in the Mustang vs the radiator in the Explorer isn't as simple as just saying one works with the 16 psi so the other should too...

Recognize the Radiator in the Explorer is a downflow radiator. The radiator in the Mustang is a crossflow. Downflow radiators traditionally take a a higher pressure cap to function correctly as the cap is located at the highest heat, highest pressure part of the system.

I am not saying it is a direct comparison either. It is a similar comparison. Same engine, same size radiator. I agree that the difference in pressure could be due to the placement of the cap. I am not sure if the pressure drop across the radiator would account for all the 4 psi difference since the down flow design does have gravity working in its favor to some extent. As for the cooling ability of one over the other, if both are the same radiator but oriented 90 degrees different, then they both cool about the same.

The main reason one orientation is used over another is due to the design of the vehicle. Low, wide front profiles work better with cross flow orientation. Tall and/or narrower profiles work better with, or can accommodate, down flow orientation. Ford probably spec'ed 20 psi for a reason. Maybe it was to cover a use scenario that 99+% of owners will never see. I do think the 20 psi cap is part of the reason we see so many radiator failures in the 4th gens. More pressure, more stress. Add in an under designed (structurally) radiator with plastic ends and the high failure rate makes sense. So far, I have not read here where one person has seen cooling issues running a 16 psi cap. I installed one earlier in the year and haven't seen any fluctuation with the temp gauge. When it gets really hot here in July and August I will monitor temps through the OBD2 port to get a better sense of coolant temperatures. Also, if I were bored, I would look to see what pressure down flow designs typically run but I am not that bored.

 

[Ddempsey328]

Hi all. New expolorer owner here. I bought an 07 limited 4.6 from my buddy couple months ago. I knew it had a coolant issue. Loses maybe a half gallon over a week or 2. I have tried find where it is leaking from with no luck. I was getting pretty close to ripping it all out lol. And then somehow, while looking to replace one of my own 18s on some web sites I found my self reading this topic. Ordered me that old 16lb cap today and we will see how it goes from there. I know where to come and read when I dont know what to do with this thing lol. Thanks fellas.

 

[Blackhawkxx]

Hi all. New expolorer owner here. I bought an 07 limited 4.6 from my buddy couple months ago. I knew it had a coolant issue. Loses maybe a half gallon over a week or 2. I have tried find where it is leaking from with no luck. I was getting pretty close to ripping it all out lol. And then somehow, while looking to replace one of my own 18s on some web sites I found my self reading this topic. Ordered me that old 16lb cap today and we will see how it goes from there. I know where to come and read when I dont know what to do with this thing lol. Thanks fellas.

If it is already leaking, the lower pound cap isn't going to do much. It will still leak. The common place for a leak is either the radiator itself or the thermostat housing.

 

[Ddempsey328]

If it is already leaking, the lower pound cap isn't going to do much. It will still leak. The common place for a leak is either the radiator itself or the thermostat housing.

Yeah I have been looking. Never seems to lose more than half a gallon or so. And the radiator cap is kind of hanky. May not ne the problem but it might be part of the problem. And it was cheap. I am going to keep my eye in it and thanks for the tip.

 

[94Eddie]

Hi all. New expolorer owner here. I bought an 07 limited 4.6 from my buddy couple months ago. I knew it had a coolant issue. Loses maybe a half gallon over a week or 2. I have tried find where it is leaking from with no luck. I was getting pretty close to ripping it all out lol. And then somehow, while looking to replace one of my own 18s on some web sites I found my self reading this topic. Ordered me that old 16lb cap today and we will see how it goes from there. I know where to come and read when I dont know what to do with this thing lol. Thanks fellas.

Welcome. A common place for coolant leaks on 2006-2010 Explorers is the top and bottom of the radiator. The places where the plastic is mated to the aluminum develop hairline cracks that leak very slowly and will not puddle on the ground. Look for dried coolant in these areas. The 16 psi cap might slow the leak and give you time before replacing the radiator. My Mountaineer had a leak at the bottom of the radiator about 1.5 years ago and was replaced.

 

[Ddempsey328]

Welcome. A common place for coolant leaks on 2006-2010 Explorers is the top and bottom of the radiator. The places where the plastic is mated to the aluminum develop hairline cracks that leak very slowly and will not puddle on the ground. Look for dried coolant in these areas. The 16 psi cap might slow the leak and give you time before replacing the radiator. My Mountaineer had a leak at the bottom of the radiator about 1.5 years ago and was replaced.

Got ya. So before it gets cold new radiator and hoses.

 

[94Eddie]

..... or before you get stranded.

 

[ThunderbirdSport]

..... or before you get stranded.

This right here. You know that most likely it's bad or soon will be...may as well do 'er up now and be done with it LOL.