can an ast be used with out the coolant overflow tank?

my friends fd has no ast and no overflow resevoir??? idk but his car never overheats or has coolant leakes...but by not having a ast or coolant resevoir wouldnt this put too much pressure on the coolan system?

he just bought a ast....So can a ast be used with out the coolant overflow resevoir? if so how wold it be hooked up..

 

anyone?

 

try searching "ast elimination". There have been a million threads on this. You buy a top fitting that has a nipple on it off of a FC(don't remember which years) and it directly bolts to your coolant filler neck, which then allows you to eliminate the AST. Thats it in a nutshell. If you search my for sale ads, I sold one a couple of months back.

 

^
http://www.rx7.org/Robinette/coolant_tank.htm

 

not the ast removal he want to remove the coolant overflow tank...

he just bought a new ast...

 

The answer is NO. There is no place for the coolant to expand to. You can remove the AST but you cannot remove the recovery tank. If he does there will constantly be air in the system OR there will be WAY to much pressure when hot.

FWIW just about every new car I see and most race cars run an AST.... but they call it an "expansion tank" I went so far as to build one from scratch for my FC project. Aluminum ones with good fittings and good lines help keep the cooling system free of air pockets and do nothing detremental
Aluminum AST > Stock AST > Just a recovery tank.

 

As far as I know a recovery tank and a overflow tank are the same thing, an air seperator tank is different.

 

Expansion Tank = AST - captures and purges air to the recovery tank. In the recovery tank the air is actually purged from the system.

Recovery Tank = Stores excess coolant while the system is hot and allows the coolant to be recovered when the system cools & the coolant contracts

Overflow tank = Catches the overflow and needs to be manually drained

You can use overflow tanks as recovery tanks but they need to be plumbed properly.

 

okay so im gonna have him get a coolant resovoir and use the ast with it....thanks guys...

 

related question: I've been running the same pressure caps on both the AST and the filler neck (13 psi or 0.9 bar) and the system never seems to suck the fluid back in after it cools off (i.e. it's always down in the filler neck), so I tried using a no spring cap on the AST, is that a problem?

 

Yes.
There could be a tiny pin hole air leak as well between the AST and the recovery tank. Or the hose clamps are slightly loose. Stock AST or aftermarket

 

use the 0.9 cap on the ast and the spring-less cap on the filler neck.