Evans Coolant and AST question
 

I am running evans coolant and wondering if I should eliminate the AST? I know that this coolant expands more than normal coolant, is this a reason to keep or eliminate the AST. I am looking for specific reasons why I shouldn't run it with this coolant, I am not looking for the neverending debate about the AST.

Thanks

well if the coolant that you are using you say expands more i would think it would be a good thing to keep the ast just cause if it expands more then it also has to contrast just as much and i think you have a more chance of air to get into your system then you normally would so if it were me id keep it, and just replace it with an aluminum one to get rid of the plastic. someone let me know if im wrong, just saw the thread and started thinking

If you properly burp the system you have no need for the ast, Evans or not. I use Evans and had it both ways, doesn't make a damn bit of difference.

Same here...no problems whatsoever since eliminating the AST and using Evans...

Doesn't matter if you use 100% coolant, water, mix or Evans. You gotta decide if you are satisfied without the AST.

I run Evans w/o an AST, no problems here.

I guess I am getting the same answers that I would get if I asked "should I eliminate the AST". I decided years ago against this and don't think I have changed my mind. The bottom line is, I personally don't think it hurts in any way to have it, but it might benefit so that is why I have left it. I was looking more for a specific reason to eliminate it with Evans, no one can seem to say why and back it up.


RedRx00- I was actually thinking along the same lines as you, and yes I have a aluminum AST, that was one of my first mods five years ago.

Let's see if I can be more specific about this.
The purpose of the AST (Air Seperation Tank) in a healthy working cooling system, is to provide a location where if the coolant experienced nucleated boiling can condense and return to liquid state. Almost all track cars have ASTs in one form or another for obvious reasons. Since the turbo charged rotory engine tends to run hotter than normal, and due to weight reduction, the cooling capacity is at a bare minimum, coolant boiling is inevitable, hence the AST.
Because of the higher boiling point of the NPG+, coolant boiling is all but eliminated. Since the coolant never goes into the gas state, there is no need for an AST.
On a side note, the AST has nothing to do with coolant expansion in the liquid state, that's what the overflow tank (also referred to as the expansion tank) is for.

I guess your original statement wasn't true? So there IS a need for the AST with regular coolant, but not with Evans. I do agree with the above statement, but wouldn't having it just give the system that much more capacity. I just read an article in grassroots about Evans and they said that a large overflow (expansion) tank is necessary for evens. Wouldn't the AST just act as a second overflow tank? Do you think there is any reason NOT to run an AST with Evans or is it just another thing I can eliminate?

Thanks for the time...

The AST is less needed with Evans. Evans will not cause the localized boiling, meaning that the cooling system (once burped and working properly) will not get gases in the system needing the AST to help eliminate.

Won't hurt either way, but I maintained it. It allows for slightly more coolant in the system and its a good place to access the cooling system. Evans will not cause the localized boiling, meaning that the cooling system (once burped and working properly) will not get gases in the system needing the AST to help eliminate.

no. it would always be full and thus increase the amount of expansion overflow capacity needed (a small amount).

AST will help purge air if cooling system has been opened for gen repair work.

For zero psi system, AST, with a .01" pill at the side inlet, helps avoid vacuum at the lower rad hose.

But, ast does provide more potential leak points.