I have an '04 EX Limited 6.0L. This past January while driving in CO from TX the truck overheated while driving stop and go in a small area looking for a particular store. The fan kicked in as it should have and it cooled some, but I begin to notice during the trip that anytime I was sitting still it would overheat. I had front and rear AC controls on heat as it was very cold. When driving normal speeds engine temps would cool down. The Heater would begin to blow cold air as the temp would rise when sitting still or barely moving. Got home and found radiator a little low of fluid and filled to just below the modified full line.

Fast forward 5 months. I've had no problems at all since until about 2 weeks ago I noticed the smell of antifreeze every time I would exit the truck. The degas bottle still looked full if you checked it cold or once you depressurized the system. No signs of puking. This past Friday after driving home from about an hour away I had to stop at a particularly long stop light and the AC began to blow hot air. I checked my temps(scanguageII) and it was getting hotter the longer I sat. Checked degas bottle when I got home no problems. I've been trying to get it to do this again but no luck. Suspected that it may be the heater core for the rear AC, but turning it on in any temp hasn't duplicated results. Any thoughts here on the EX community? The 6.0 guys are trying to help, but thought that the complications of the second AC may be what is causing my issues, and those guys mainly deal with the truck engine problems.

 

Glad you posted that last part because I was getting ready to move this thread to the 6.0L forum to get you their help.

Stewart

 

I doubt the rear A/C would complicate an over heating issue. I have never seen a bad heater core cause an overheating issue.

So you are using zero coolant correct? There is no sign of coolant on the ground?

What area of the engine compartment are you smelling coolant?

My bet would be a water pump. Once you get going it cools down?

 

I agree that rear A/C is probably not a problem. I'm not currently able to detect any loss of coolant. Definitely no visible leaks anywhere.

As far as the location of the highest smell, I couldn't pinpoint. But getting out of drivers door I was smelling it consistently for about a week before it overheated last Friday.

Not sure of the water pump. Saturday it was hotter than normal, but 15 degrees pulling my boat a short distance. Small boat, total weight trailer and all less than 5000 lbs.

 

I was just watching a Youtube video about the vacuum system and one common almost common denominator is engaging 4wheel drive. I don't remember ever engaging 4 wheel drive on Friday, but most definitely in CO and on Saturday. I will try this out tomorrow while driving around town. I know the vacuum system controls the heater valve, but how would this cause the truck temps to rise. I get how it would mess up the A/C and heat, but not how it would effect engine coolant temps upward

 

Check or do the free rental at ##### parts store and just pressure test it. My guess is you have small leak or 2 preventing the system from pressurizing, this will cause coolant to boil prematurely resulting in a over temp. I don't have a 6.0, my 7.3 is getting another new water pump due to a small leak. Do yourself a favor and get OEM quality parts, not cheap auto part store stuff. I learned the hard way. Also check the heater bypass valve for coolant leaks on passenger side near valve cover, if in same spot as 7.3's. My leak is so small what does leak evaporates leaving only the red dye from the coolant. Test your radiator cap also or just replace it. I bought a after market degas bottle that leaked no matter what cap I had, but a pressure testing the system will be the best place to start.

 

ATC, I agree with the logic you've laid out. I didn't think of the heater valve being a source of a leak, but it would make sense of several things that I'm experiencing. The coolant smell that I was smelling. I also have a vacuum issue. This morning it wouldn't go into 4x4 mode. It was cool out, and my drive to work is only 8 minutes so not a good test of other issues, but it has always gone into 4x4 quickly after turning the dial before. I'll be replacing all the vacuum hoses soon and checking the other possible problems.

 

For starters, where in Texas are you?

Chances are some one of us are close by and can help....

The last few times I smelled coolant on my 6.0:

-The radiator had a slow, but unnoticeable leak. It finally cracked enough to where I could strongly smell coolant and explained my overheating issue July 2015. The radiator was replaced with a Mishimoto Radiator.

-My degas bottle developed a small leak and was draining my already expensive coolant. Ford, even with my discount, was a little too proud of the part, so I bought the Dorman part with a lifetime warranty and get this....a better cap.

-February of this year, my waterpump took a dump and sprayed coolant all over the front cover of my engine. I got home without issue, I replaced the waterpump was with a dieselsite pump that uses a steel impeller as opposed to the stock plastic. Come to find out, Ford has since revised the waterpump and it now uses a steel impeller for the same price as the Dieselsite pump.

-Another place to look is the left rear corner of the engine, you'll see the hoses for the heater core. Ford used a plastic connector where they should have used metal. This leak can acutally conceal itself unless you know what you're looking for. It smells, but since it drips on the exhaust manifold and never the ground, it's easily concealed.

 

I live in Lake Jackson.

 

I've had a few issues over time with smelling coolant.

One was the plastic tanks on the stock radiator. Replaced that with a Mishimoto and called it done.

Then it was the heater connector that was leaking right onto and burnt out injector #5...that was fun.

Then it was the plastic Y connector under the degas bottle that decided to snap under light pressure when attempting to access the EBP sensor.

Haven't had to deal with the water pump yet.....yet.

Plastic seriously has no place in the coolant system due to the heat cycles these engines produce. But...I'm no engineer.