7.3 now running hot in the mountains

[dancorn]

Driving a 2003 E350 w/7.3 has 410,000 miles and has never had a heat issue until yesterday. Traveling east on I 70 in Colorado I was driving up Vail Summit and at 9200 feet the gage went into the red. I pulled over and let it idle with heater running. It cooled in 10-15 minutes and I proceeded upward. it went into red again at 9660 feet. Pulled over and then proceeded. This went on every 400 feet or so until I topped the Summit at 11700 feet. There was one more high Summit to go after this one. The same thing happened. There were also gusts to 50 MPH were they were about all tail winds. After topping the last peak there was no more overheating problem. I have crossed this same road at least twice in the past two years without issue. The 10-to 15 mile trip took about 90 minutes counting the sitting on the shoulder times. I was empty so it was not a weight issue.

I am wondering what changed. Is it possible that using biodiesel or Rotella full synthetic oil is a problem? I had the all the old factory fluids changed last month so I would have expected an improvement in cooling. Weak water pump? What else?
I don't know how to replicate the problem short of climbing that darn mountain again and I would rather eat dirt than go through that again. Any suggestions on how to test for proper cooling ability?
Any idea or information is appreciated.

 

[Turtle]

Has the radiator been backflushed? Sounds like a clogged radiator. When it running, touch the far side of the radiator, then the other side. If one side is noticeably cooler, there ya go. Flushing and backflushing may do the trick, otherwise it'll need a new one.

Also check the fan clutch. Worn or missing bearings can cause the fan to move too slow, or to even seize up and constantly run too fast at lower engine loads (causing the engine to run 10 or 20 degrees cooler than normal) or too slow at high loads causing it to overheat.

Check the rubber seal on the radiator cap, too, for any cracks or splits that would allow pressure to escape. Boiling points change at high altitude which can cause overheating, especially if there is a pressure leak.

Might be the water pump isn't moving water like it should. Also couldn't hurt to replace the thermostat.

 

[zorry]

At 410,000 miles would it be overkill to just throw in a rad,wp,fan clutch,etc. At home, in a reasonable shop at your convenience ?
Not like we're talking class 8 parts here.
Just curious...,

 

[Monty]

Without air, the engine over works. You might check your air filters and air-to-air, (if there is one on the unit). Altitude changes nothing except oxogen concentration. If it isn't breathing, it will over heat.

 

[usafk9]

Altitude changes nothing except oxogen concentration.

....which is measured by the MAP sensor to tell the computer to adjust air intake to compensate for the higher altitude/lower oxygen. If it's faulty, your 'puter may think you're at a lower altitude/'normal' oxygen concentration.

Personally, I'd do do the radiator flush first, then test/replace the MAP sensor. Both are cheap and easy fixes. Then I'd work up to the tad-more-expensive parts. However, as Zorry said, they ain't class 8 parts. Might be good to replace all.

 

[Turtle]

Altitude changes nothing except oxogen concentration.

In addition to reduced oxygen (which is compensated for the MAP sensor, as has been mentioned), altitude changes atmospheric pressure. At higher altitudes you have lower atmospheric pressure, which affects the temperature at which liquids will boil.

Pressure cookers work they way they do because they increase the pressure in the cooker and allow you to boil stuff at a higher temperature than boiling at sea level. The water in an open boiling pot will never reach a temperature higher than 212° F, no matter how much heat is applied, because water evaporates as steam. In a pressure cooker under higher pressures, the boiling point of water increases as the pressure increases, and can reach up to 250° F.

The opposite is also true, when pressure decreases, as with a rise in altitude, the temperature at which water will boil decreases.

Properly mixed engine coolant will boil between 223°F and 235° F at sea level, depending on the type of coolant and water-to-coolant ratio. Yet the temperature of engine coolant can sometimes reach 250° F to 275° F. To keep the coolant from boiling, something additional must be done to raise its boiling point.


The cooling system uses internal pressure to further raise the boiling point of the coolant. Pressure cooker again. Most vehicles have a pressure limit of 14 to 15 pounds per square inch (psi), which raises the boiling point another 45° F so the coolant can withstand the high temperatures. TDI engines, especially aluminum engines, may need 20 or 30 psi, or more to keep the engine cooler. The pressure in most vehicles is regulated by the radiator cap. If there is a pressure leak around the radiator cap at higher altitudes, the internal pressure of the cooling system will drop significantly more than it will at lower altitudes, thereby causing the coolant to overheat. It's basic physics. The radiator cap isn't just a cap, it's the pressure regulator for the entire cooling system, just like the pressure regulator on a pressure cooker. That's why if you are overheating at higher altitudes you should not ignore the radiator cap as a possible cause. It often is.


Extreme anything - heat, cold, altitude - will expose a weakness in the cooling system. Issues that aren't issues at low altitudes or temperate climates, will manifest themselves at the extremes. Trick is to figure out which part is failing. With that many miles on it, it could be any of the things already mentioned, or a combination of things. Vehicles that do what yours is doing, the usual culprit is a thermostat, clogged radiator, radiator cap, fan clutch, lots of dirt and debris in the radiator fins, water pump, generally in that order, but there may be one or more other causes.

 

[guido4475]

Turtle hit the nail on the head.It is surprising how much dirt and fuzz gets trapped between the condenser and the radiator.But you really can't see it.Spend a Saturday, and pull the radiator, and get a couple of cans of a/c coil condenser cleaner from Home Depot, and satuarate it, then rinse it out, inside and outside, with a garden hose, not a pressure washer, unless you want bent over fins.My 03 E-350 7.3 did the same thing.I did it every year after that, and it was amazing how much stuff collected in there.The same with all of the coolers and condenser on the vehicle.Wash everything out.Mine ran cool as a cucumber after that, and the a/c will work alot better at an idle, also, since the air will flow like it should through all of the coolers.

 

[zorry]

That Turtle,he's one smart amphibian.

 

[OldGuy]

While this is true, being in a closed loop system the cooling system should never experience a pressure drop unless the cap is off.

In addition to reduced oxygen (which is compensated for the MAP sensor, as has been mentioned), altitude changes atmospheric pressure. At higher altitudes you have lower atmospheric pressure, which affects the temperature at which liquids will boil.

Pressure cookers work they way they do because they increase the pressure in the cooker and allow you to boil stuff at a higher temperature than boiling at sea level. The water in an open boiling pot will never reach a temperature higher than 212° F, no matter how much heat is applied, because water evaporates as steam. In a pressure cooker under higher pressures, the boiling point of water increases as the pressure increases, and can reach up to 250° F.

The opposite is also true, when pressure decreases, as with a rise in altitude, the temperature at which water will boil decreases.

Properly mixed engine coolant will boil between 223°F and 235° F at sea level, depending on the type of coolant and water-to-coolant ratio. Yet the temperature of engine coolant can sometimes reach 250° F to 275° F. To keep the coolant from boiling, something additional must be done to raise its boiling point.


The cooling system uses internal pressure to further raise the boiling point of the coolant. Pressure cooker again. Most vehicles have a pressure limit of 14 to 15 pounds per square inch (psi), which raises the boiling point another 45° F so the coolant can withstand the high temperatures. TDI engines, especially aluminum engines, may need 20 or 30 psi, or more to keep the engine cooler. The pressure in most vehicles is regulated by the radiator cap. If there is a pressure leak around the radiator cap at higher altitudes, the internal pressure of the cooling system will drop significantly more than it will at lower altitudes, thereby causing the coolant to overheat. It's basic physics. The radiator cap isn't just a cap, it's the pressure regulator for the entire cooling system, just like the pressure regulator on a pressure cooker. That's why if you are overheating at higher altitudes you should not ignore the radiator cap as a possible cause. It often is.


Extreme anything - heat, cold, altitude - will expose a weakness in the cooling system. Issues that aren't issues at low altitudes or temperate climates, will manifest themselves at the extremes. Trick is to figure out which part is failing. With that many miles on it, it could be any of the things already mentioned, or a combination of things. Vehicles that do what yours is doing, the usual culprit is a thermostat, clogged radiator, radiator cap, fan clutch, lots of dirt and debris in the radiator fins, water pump, generally in that order, but there may be one or more other causes.

 

[Turtle]

While this is true, being in a closed loop system the cooling system should never experience a pressure drop unless the cap is off.

And yet a cracked, worn, or broken rubber seal under the cap will cause a pressure leak despite the cap being on. The key phrase is "closed loop". If the seal is bad, it ain't closed. It won't necessarily be a coolant leak, but rather a pressure leak.

Is this stuff truly not common knowledge? Has nobody ever tested or seen a failed radiator cap before?

 

[guido4475]

The radiator caps on those vans are KNOWN to go bad prematurely as well.Go to powerstroke help.com and bill has a video on those rad caps,explains the whole thing.Real good guy.

 

[OldGuy]

Agreed 100%. Perhaps I did not read your post slowly enough .

And yet a cracked, worn, or broken rubber seal under the cap will cause a pressure leak despite the cap being on. The key phrase is "closed loop". If the seal is bad, it ain't closed. It won't necessarily be a coolant leak, but rather a pressure leak.

Is this stuff truly not common knowledge? Has nobody ever tested or seen a failed radiator cap before?

 

[kg]

Lower hose may be weak and kinked. happened to me.

KG Stay safe

 

[BobWolf]

Not sure if turtle hit on theese but check your air systeme. Air filter, take the tubes off and make sure they are clean they do tend to get crud inside after a while. Make sure your couplings are in good shape no leaks and soft, CAREFULY use a blow gun and blow out the inside of the charge air cooler/intercooler DO NOT USE WATER you can clog it up or send mud through the turbo. Also check the torque on the turbo bolts look for cracks or signs of leaks.
Good luck

 

[dancorn]

Turtle was right. It was the fan clutch. Thanks all for the help.

 

[moose]

Turtle hit the nail on the head.

Now i won't sleep for a week...