The most common reason for that is that your radiator cap sealing gasket is bad. There is a rubber gasket on the inside of the cap that maintains a seal rated at a certain pressure. If the pressure of your system in exceeding that of the caps rating, water vapor may vent out, or the cap seal is bad and it needs to be replaced. If the cap needs to be replaced it is important to do that because cooling system level is gradually depleted by the slow realease from the cap, and a low coolant / overheat condition can occur with out any apparent warning.
Does you cap seep water out all the time, and is it enough that it ends up leaking on the ground noticeably? Let me know and I can give you a more acchcurate answer.
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This is a 6.0 Diesel? This could be a sign of a serious condition. When these engines overheat, the head bolts stretch and cause the head gaskets to leak. The compression from the combustion chambers pressurize the cooling system, and cause the leak from the coolant bottle. You have 2 symptoms of this common problem of the 6.0 diesel. Take it to your local Ford dealer for the appropriate repairs. If you have under 100K miles and have everything on the engine is STOCK, it will be covered under warranty.
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Anything is possible, but I know that the concern you have is a common failure. I hope that it's as simple as a plugged radiator. I found this TSB
This article supersedes TSB 08-3-7 to update the Service Procedure.
Some 2003-2007 F-Super Duty, 2003-2005 Excursion and 2004-2008 E-Series vehicles, all equipped with a 6.0L engine, may exhibit:
The conditions typically occur when operating the vehicle under a load such as trailer towing, uphill driving, or both.
Follow the Service Procedure steps to correct the condition.
Prior to making any repairs, verify the coolant level is not overfull. The new coolant fill level is at the "MIN" line of the degas bottle cold. Overfilled coolant levels will cause coolant to vent from the degas bottle cap.
Follow IDS PVT Datalogger instructions on screen.
The only tools approved by Ford Motor Company for cleaning the cylinder head and deck surface are plastic (Figure 6) and wood scrapers, combined with the use of Motorcraft®Metal Surface Prep. Ensure that the mating cylinder block deck surface is completely free of solid contamination, corrosion, and fluids.
Figure 6 - Article 08-11-3
Figure 7 - Article 08-11-3
Figure 8 - Article 08-11-3
Eligible Under Provisions Of New Vehicle Limited Warranty CoverageIMPORTANT: Warranty coverage limits/policies are not altered by a TSB. Warranty coverage limits are determined by the identified causal part.
NOTE: The information in Technical Service Bulletins is intended for use by trained, professional technicians with the knowledge, tools, and equipment to do the job properly and safely. It informs these technicians of conditions that may occur on some vehicles, or provides information that could assist in proper vehicle service. The procedures should not be performed by "do-it-yourselfers". Do not assume that a condition described affects your car or truck. Contact a Ford, Lincoln, or Mercury dealership to determine whether the Bulletin applies to your vehicle. Warranty Policy and Extended Service Plan documentation determine Warranty and/or Extended Service Plan coverage unless stated otherwise in the TSB article. The information in this Technical Service Bulletin (TSB) was current at the time of printing. Ford Motor Company reserves the right to supercede this information with updates. The most recent information is available through Ford Motor Company's on-line technical resources.
Copyright © 2008 Ford Motor Company
I cannot stress how important it is to have your engine stock. Anything that was added on or modified from the day you bought the truck will cause the warranty repair to turn into a customer pay job! Put it back to stock if anything has been modified.
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