External coolant tank - what for?
 

In my car there is a strange looking non-OEM coolant tank.

Why did the previous owner install it?
Any benefit of such part?

Looks like there is some kind of aftermarket radiator also.


https://cimg8.ibsrv.net/gimg/www.rx7...ebf1cb16f9.jpg

https://cimg9.ibsrv.net/gimg/www.rx7...480d3e938d.jpg

https://cimg0.ibsrv.net/gimg/www.rx7...5a7f8604cc.jpg

Looks like an air separation tank (AST) - does what the name says. Not a mandatory thing though.

They come stock on FDs as a black container that sits in front and below the alternator pulley.

It's really common to see people replace them for aluminum tanks as the plastic ones get brittle and fail with age. Looks like someone has installed an aftermarket one on yours.

ya..but that is an FC engine bay.

^Noticed that too.
:dunno: Maybe the previous owner had trouble purging air from the system for some reason. And a 16 psi cap seems a little strong too. What's normal on the FC?

13 psi is stock, I believe.

is that this thing circled in my FD picture? i was wondering what it's purpose was as well:

https://cimg3.ibsrv.net/gimg/www.rx7...90208d5318.jpg

there will be many questions from me of what i can leave out (hose wise, EGR wise, and vacuum wise) once i start piecing mine back together.

^ Yes...that's the (aftermarket) AST. But call it a wild stab in the dark, I'm thinking your coolant leak is elsewhere.

So what exactly is the benefit of such part in FC?

Does it improve cooling?
Or just helps with bleeding during coolant change?

Should I remove it? I like to keep the car stock.