Well, I'm sure I mentioned it earlier, but I'll bring it up again because time has passed and I can see how its working.

I mentioned that I converted this van over to Evans Waterless Coolant. I have to say I am very impressed, and intend to convert more of my vehicles over when opportunity permits.

The big advantages to using this coolant are:

More consistent cooling
No pressure build up
Less stress on radiators, heater cores, and hoses
Easy service
No maintenance
No corrosion
Lower long term cost

The cons are
higher initial cost
lack of local sourcing

Overall, my view is this. Virtually all components failures on our coolings systems: heater cores, radiators, hoses, head gaskets, etc. are due to the problems inherent with water based coolants.

Pressure
Simple fact, water boils. When it boils and turns to steam, it produces pressure. That pressure is 16 psi, which when you think about it, is a lot of stress for the components the system is made from. When the system cools down, the pressure drops down to a slight negative, as the coolant displaces less volume, and flows back from the overflow into the radiator. This means your cooling system is not only being exposed to this type of pressure, but it is being exposed to extremes of pressure. The Evans coolant contains no water, and does not boil under normal engine temps. This means there is no pressure build up beyond normal expansion of the fluid, which is minimal.

Corrosion
Water acts as an electrolyte, especially if it is not pure. The minerals corrode the various metals, which creates a galvanic action, which destroys the cooling system from the inside. Coolant contains corrosion inhibitors, but they wear out over time, and they are not 100% effective in the first place. The Evans coolant contains no water and has no galvanic action. It has corrosion inhibitors that do not deplete over time.

Servicablility
Because of the pressure, in the even of an issue, the pressure has to be released prior to servicing. Because the Evans coolant does not build up pressure, breakdowns are less likely in the first place, but if they do occur, the system can be opened live, without a geyser going off.

Consistent cooling
In a water based system, particularly as temperatures rise, the coolant wants to turn to steam, and the pressure is the main thing that prevents this from happening. Even so, as the coolant passes through the heads and water jackets, it absorbs heat and wants to flash to steam. If the engine is under heavy load, and the system is struggling to keep up, some of the coolant can flash to steam, and form steam pockets. Thought he initial formation of these pockets absorbs heat, once the pockets form, heat transfer through the pocket is slowed, creating hot spots and uneven cooling. This can lead to the cylinder heads cracking, pinging, accelerated valve wear, and head warping. Obviously head warping leads to head gasket failure. Because Evans coolant does not boil, it does not form steam pockets, as engine temps rise it continues to cool the engine effectively and evenly. This means that not only does it cool better, but the engine can also be safely run hotter without the risk of damage.

I am now a believer, and personally recommend this stuff. I have tested it, and it works great. I intend to convert my '87 Thunderbird and my '86 Merkur.

 

There are some inaccuracies here. Liquid water at standard atmospheric pressure will boil at 212F. At higher pressures, water will boil at higher temperatures. The point of a pressurized radiator cap is to increase the temperature at which the liquid water boils because liquid transfers heat better than steam. With a pressure cap of 15 psi (gauge), the boiling temperature of water is about 250F.

Water by itself is a good electrolyte, even without impurities. Just see what happens when you spill some water across two plated terminals of a typical battery; instant corrosion. Any two dissimilar metals immersed in even pure water will form an electric cell, and if you provide a path between the metals for current to flow, the immersed metals will start to dissolve.

One problem with using water and ethylene glycol is that the mix naturally forms glycolic acid, which is very corrosive. Most commercial anti-freeze have added corrosion inhibitors to counteract the corrosive effects of glycolic acid, but they do get consumed eventually.

Another problem with using water with glycol as a coolant is that pure glycol has only about 60% of the heat capacity of water. So a water and glycol mix will have reduced heat transfer rate from pure water. I think the Evans coolant is pure propylene glycol, so its heat capacity and conductivity will be worse than a water and glycol mix. This means increased coolant and operating temperatures.

Also, pure glycol is also much more viscous than water, and will put a strain on the pump. Other parts will get stressed as well. Parts like hoses fatigue from repeated heating/cooling and pressure cycles, and eventually fail. These will be exacerbated with a coolant that's more viscous running at a higher temperature, even if the operating pressure is lowered.

 

Yes. I fail to see the inaccuracies though. The pressure is the only thing trying to prevent it from turning to steam. But the pressure is building up because its trying. From past experiences I have seen, and others are familiar with this too, I have seen Aerostar do wild temperature swings. Now one could argue that it is an air pocket that has gotten trapped, which causes these temperature swings. To describe what I'm seeing, and just to be clear, at some point all of my Aerostars have done this, is the temperature gauge will go from some seemingly normal temperature, then rise rapidly to something pretty hot, then drop back down to normal in a short time period. What seems to be the prevailing theory is air pockets that have not gotten purged out. The problem with that theory is that this issue shows up when the van is hot, or on hot days, and not other times. The van has had plenty of time to purge itself, so it would not be logical that it would still have issues months afterwards. This means that something else is going on. I think what happens, is that the coolant in the head is getting well over 250 degrees, and is flashing to steam, forming an air-pocket around the thermostat which is both reducing flow, and causing false readings. When I converted to Evans, this issue no longer happens.

As far as increased coolant and operating temperatures, yes the Evans guys did indicate that the coolant capacity is reduced, but to counter that argument, because no steam flashing is occurring, the cooling is more consistent. This means that as engine temperatures increase and approach what would normally be the danger zone, the Evens does a better job, and basically raises the safe limit. In my experience, once my coolant temps started to exceed 220 F, the water based coolants start to fail to cool, and the temperature will then start to continue to climb. With the Evans, in my tests doing the same things that caused an overheat on water based coolant, I get a very slow temperature climb, and it never gets out of hand, the hotter it gets, the longer it takes to get hotter. The highest I have managed to get is 2/3rd up the gauge. When I ran the same vehicle before on the same stretch of road, It would get to about 1/2 up the gauge, and then start doing wild fluctuations, pegging out, then dropping back down, then pegging out again, then dropping back down, and it would pretty soon peg out all the time, and I'd have to pull over and let it cool off. This stretch of road is local canyon, and I have few vehicles that can go up it without overheating. This Aerostar with the new coolant is one of them. I can go up that canyon without worrying about overheating the system or popping a hose, or puking coolant all over the parking lot.

The difference in viscosity is not significant. I'm sorry, but running at under 5 psi versus running at 16 psi is a huge difference. The strain on all parts should be reduced. The pump might be the only component that gets stressed more, and even that is doubtful. When the system is hot, you can go squeeze the hoses (careful not to get burned). With water based glycol mix, the hoses are hard, and you can feel the pressure inside. With the Evans, the hose are maybe only slightly pressurized, not much harder than when the system is cold.

 

Maybe it was the way you worded it.

The viscosity differences between water and propylene glycol is actually quite huge, ranging from about 200x at 32F to about 10x at 200F. With a typical 50/50 mix, the differences drop to about 10x at 32F to about 3x at 200F; still significant. See this chart from Dow Chemical:

Dow Answer Center

They also have vapor pressure charts, showing boiling points at various concentrations, so it does produce substantially less pressure than water.

But do let us know about long term results, like at the first change out.

 

There is no first change out, the stuff is lifetime coolant that does not corrode, boil, evaporate, or anything else. It is designed to be completely maintenance free. If you ever drain for any reason, you collect it all and reuse it.

 

Cool thread! If I ever rebuild a 4.0, I'll know what to reference! Also, those EDIS modules sound like the old Motorcraft elec. ignition boxes back in the 70s. I had a 77 F100, and once that module went out, right around the corner from my house.