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Camper_Jeff___K's avatar
Camper_Jeff___K
Navigator
Feb 25, 2026

Dealing With Coolant System Pressure and Temperature

VIDEO Dealing With Coolant System Pressure And Temperature  VIDEO

The concept is to cool and condense steam heading for the Degas Bottle, back into liquid to lower pressure, reducing the chance of over pressuring the cooling system, thereby lowering the chance or amount of coolant released by the pressure cap.

So far, the results are to blow a very small amount at 200 degrees under load, going up a long grade.

Previously, before the cooler/condenser, the coolant system would blow coolant starting at 196 - 198 degrees going up a long grade. At 200 plus degrees previously, the coolant would blow all over under the hood.

The headgaskets have not failed in this engine. This is purely a heat, expansion, pressure, cavitation, steam, vapor, issue. The condenser needs to lay flat, level, and able to freely flow steam vapor through the cooler to the Degas Bottle. A different orientation causing pooling or accumulation, would impede the flow of steam vapor through the condenser and impede function.

I believe I'm on the right track to remedy the problem. The next step is to replace the antifreeze coolant with CATERPILLAR Anti Cavitation Coolant.

We shall see if that does the trick...

 

14 Replies

  • Camper_Jeff___K's avatar
    Camper_Jeff___K
    Navigator
    Feb 27, 2026

    Here is a picture inside the waterpump housing.  You can see the obvious shiny area where the old composit impeller was rubbing. If you look closer, you can see the pitting in the metal that is a telltale sign cavitation is happening which clearly it is. Cavitation also happens on cylinder wslls due to engine vibration. Caterpillar engine coolant is designed to minimize cavitation from happening. This condense atop of the engine is there to condense steam vaporization pressure caused by the various sources of cavitation and lower cooling system pressure by condensing steam vapor back into liquid. 

     

    • StirCrazy's avatar
      StirCrazy
      Moderator
      Feb 28, 2026

      the factory ford stuff should be a anti-cavitiation antifreeze also, they used that even back with the 7.3.  if a modren diesel doesnt have it I would be surprised, or suspect some one who didn't know better changed the antifreeze and put the wrong stuff in it.

      what did the old impeller look like, do you have a side by size comparison of the two impellers?   

      • Camper_Jeff___K's avatar
        Camper_Jeff___K
        Navigator
        Feb 28, 2026

        I posted a waterpump replacement video a couple months back. I show the old pump and take several measurements of both old and new pumps and impellers.

        I have found a waterless antifreeze that was featured on Leno's Garage and Project Farm. It's non waterbased and doesn't boil until 260-280 degrees. It has strong resistance to cavitation. I think it is EVANS costing about 50.00 a gallon. They say it doesn't expand when hot like water-based coolants.  I'll have to rinse out the old antifreeze from the engine to make the change. The waterless stuff will tolerate up to 3% water.

        The waterless coolant may be the cure I'm looking for.

  • Grit_dog's avatar
    Grit_dog
    Navigator III
    Feb 26, 2026

    As always, glad you have something to fiddle with to occupy your time and you appear to enjoy it.  But holy moly, sure is a lot of trouble and work and $ when there’s many brands and models of diesel trucks with none of these issues to worry aboot.  

    • Camper_Jeff___K's avatar
      Camper_Jeff___K
      Navigator
      Feb 27, 2026

      We were driving in the 85 to 90 heat at 65 mph yesterday and had no issues. I allowed the coolant temp to hit 196 before tuening the blue wire fan switch on. Had no coolant loss. Temp hit 200 a few days.back and there was.a tiny amount of coolant loss, not the big loss we got before the simple condensor installation. It is apparently helping a fair amount.

      There are other items that could be problematic. The heater core may be clogged just as the stock radiator was and need replacing. It is also possible I need to install a new oil cooler. Not a lot of money, just time, I've got time and the ability. Buying this truck F550 4x4,  in such nice condition with 78K miles for $20K, I can put a lot of time and money into it, and still be ahead of the game.

      Yesterday at the Wayside Oasis, a nice gentleman was really interested in knowing about the truck. He bought a 2020 Chevy truck for 73K. He was amazed at my truck when I told him about it including it's troubles.

      • Grit_dog's avatar
        Grit_dog
        Navigator III
        Feb 27, 2026

        Someone bought a 6 year old truck for $73k?   All that proves is that person is not well read about vehicle values. If you meant, new, 6 years ago, that makes more sense. 2020 was the first year of the non Allison trans (first year 10 speed).  Maybe not the best for a first year major component change but I’d be interested to hear the “troubles” you told him he was “going to have.”  You can hook n book any L5P, Alli or 10speed, with little to no worry about anything  


        I agree, it’s in beautiful condition, but there’s a reason my last 2 Cummins diesel pickups sold for 50% more than your purchase price, one with double the miles and the “bad” 68rfe and one with almost triple the miles and a G56. 
        Dealer got lucky someone actually wanted that F550, much less paid top dollar for it. 

    • StirCrazy's avatar
      StirCrazy
      Moderator
      Feb 27, 2026

      man thats what I was thinking, I know guys towing giant 5th wheel toy haulers in the mountians with 6L and don't have any issues.  

      • Camper_Jeff___K's avatar
        Camper_Jeff___K
        Navigator
        Feb 27, 2026

        Overheating is a well known issue with this 6 liter PSD. There are Lots of kits available to help cool the engines and oil better.

  • bigfootford's avatar
    bigfootford
    Nomad III
    Feb 26, 2026

    Hope you get this resolved.  I left a note on your tube page about my experience with cavitation caused an aftermarket coolant pump impeller clearance to the housing.  

    I see that you have a picture of what looks like the pump impeller.

    Jim

    • Camper_Jeff___K's avatar
      Camper_Jeff___K
      Navigator
      Feb 28, 2026

      I'm going to try EVANS waterless antifreeze.  Has a boiling point of 260-280. Supposed to be strongly cavitation resistant.  High boiling point means less expansion, no boilovers. 50.00 or so a gallon x 3.

    • Camper_Jeff___K's avatar
      Camper_Jeff___K
      Navigator
      Feb 27, 2026

      I did a changing the coolant pump video when I installed the Bulletproof Diesel Waterpump. You could see a couple shiny areas in the pump housing that are probably from cavitation. Diesel engines are also subject to cavitation on cylinder walls. This engine I believe has issues with that cavitation and the resulting increases in pressure due to steam being created. That is what this condensor is an attempt to address. So far, it does actually seen to be making a difference. Far as I can tell, I'm the only person on YouTube, or otherwise going at the issue from the condensation angle. Turning steam vapor back into a liquid state. Steam is greatly expanded liquid,  liquid is greatly condensed steam. Condensing the steam into liquid before being returned to the DeGas bottle seems to be helping.

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