06/09/2026
No More 6.0 Liter Degas Bottle Coolant Boilovers
VIDEO https://youtu.be/Mamm_4BK444
After 150 miles of test driving, I was unable to make the engine blow coolant out the degas bottle. I never turned on the main engine fan using the blue wire switch modification. I am declaring my overheating and over pressure problems fixed. All testing was done with the 4000 pound Truck Camper on the F550. I am now able to comfortably drive up hills that would make my engine get hot and build pressure causing coolant to blow out of the degas bottle. Everything I had tried to correct the problem helped but completely fix the issue. This latest attempt to fix the problem with heat and pressure seems to have worked. I installed a Mishimoto Degas Bottle and larger hoses and fittings. The connections are also lower and closer to the water pump intake which helps. Combining the hoses closer to the water pump encourages coolant to be sucked into the pump. Being lower from the degas bottle increases downflow with help from gravity. Using larger hoses and fittings lowers pressure, back pressure, and increases flow. Where the heater and coolant filter hoses recombine into 1" hose is a recombination of the two circuits that were divided at the Tee by the alternator, half going to the heater core, and the other half going to the coolant filter and through the Hayden 1040 radiator in front behind the AC Condenser and in front of the Intercooler. Since half the circuit is cooled by the heater core, I decided the other half should be cooled by an equivalent auxiliary radiator. The degas bottle was restored to factory plumbing with the addition of the two Hayden 405 transmission coolers being used as radiators. The 3/8" degas hose from the top of the engine, originally meant for the EGR cooler, goes up to the two coolers and flows through them in series, then into the degas bottle input. The degas output goes to the top of the radiator connection. I did not connect the coolant filter return as many do into the degas to radiator hose. I decided to use the original IPR filter method and recombine with the heater core hose return under the degas bottle. I did not experience any benefit from using that connection earlier so left that hose factory untouched and recombined into the 3/4"x3/4"x1" Tee. That connection connects into the 1" SS Wye down from the Mishimoto aluminum degas bottle and immediately, about 4", into the water pump. This setup has resulted in a successfully functioning cooling system. With the new setup, I have not had to use the blue wire switch to turn on the main engine fan to full lockup. The cooling system is now able to achieve adequate cooling without the fans assistance. The Hayden 1500 CFM electric fan does turn on about 188 degrees but in all honesty, it's added ability to cool the engine is not that much. What it really does well is bring the AC temperatures down in the cab making hot summer days and trips south to Arizona etcetera, much cooler and more comfortable. There you have it, after throwing plenty of effort and a couple thousand dollars at it, I now have a rock solid cooling system on my 2006 6.0 Liter PSD.
After 150 miles of test driving, I was unable to make the engine bl...
