From this thread:
http://www.tractorbynet.com/forums/trailers-transportation/318815-6-0-power-stroke-questions.html
Ford designed the EGR coolant flow to go through the liquid/liquid oil cooler first, then to the EGR to cool incoming exhaust gases. The coolant side of the oil cooler has very small coolant passages that is prone to being plugged up. When this happens, coolant no longer flows through the oil or EGR cooler and the EGR cooler starts overheating and eventually fails, leaking coolant into the cylinders. Enough coolant leaks and you can then lift the heads leading to a headgasket failure.
So in addition to this poor EGR cooler design, Ford also uses their universal Gold coolant in the 6.0. This is a good coolant except not for diesel engines with EGR coolers since the Gold coolant has silicates in it. These silicates under high temps, precipitate out and, you guessed it, plug up the small oil cooler coolant passages. Now couple this with the fact that Ford designed the 6.0 heads with bolts (180ksi yield) instead of studs (220ksi yield) and you have a recipe for disaster.
Simple fixes for the above:
- Install a coolant filter - stat!
- Replace the Ford Gold coolant with CAT EC-1 spec'd ELC (or Ultra ELC) coolant. CAT EC-1 coolants have no silicates that will precipitate out under high temps.
- Install an aftermarket gauge that will allow you monitor coolant vs oil fluid temps. +15 degrees difference means you have a plugged oil cooler and an impending EGR cooler failure. Example is a Scangauge II that will monitor ECT and EOT.
Upgrades include installing an EGR delete kit and replacing the head bolts with studs (plus alternator and battery cable upgrades).
Once you do the above, the 6.0 is pretty bulletproof.
Those who say to "drive it like you stole it" are exactly right. These trucks need to be worked, not pansied around getting groceries.
Hope this helps.
