custom overflow tank is this right?
 

Ive been searching for a universal overflow tank and found a few things... this picture was taken off another thread recently discussed.. now is this drawing correct as far as a proper setup for a overflow/recovery tank for our car?

https://www.rx7club.com/attachment.p...1&d=1189178499

if so i am going to just buy a universal tank with the fittings in those locations and properly install it according to that diagram

That looks fine.

I like my turbo ;)

why don't you ask the guy that posted that pic?? Roen? or TitaniumTT?

i would however the thread i pulled it from there was alot of pissin and whatnot about the proper setup and nobody actually confirmed if it was the correct setup

Yeah - kungfuroy got a little bent out of shape when I asked him to explain himself. While that will work just fine and I built mine exactely like that - it's far from ideal. Give me a few minutes - I shall return with pics

this thread?
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/overflow-tank-options-need-relocate-allow-fmic-breath-686054/

Overflow or Puke tank
 

An overflow or puke is just that - it catches overflow and stores it until you drain it out. Oil catch can kinda thing only for coolant. You'll notice how whatever fluid gets deposited into the tank cannot be siphoned out automatically. It can only be drained. These have no business being on a rotary the way they are plumbed.

https://www.rx7club.com/attachment.p...1&d=1200016315

^^^^^^my overflow tank doesnt work like that mine has coolant in it while my car is turned off then when my car is started the coolant gets sucked in by vacuum i think then when the engine is off it gets pushed back into the overflow tank

Recovery Tank V1
 

A recovery tank is used to store coolant while the engine is @ operating temp. A recovery tank holds the coolant that has been pushed past the pressure cap. When coolant heats, it expands. Open a cold radiator cap and there should be no pressure and theoretically a small amount of vacuum. That's becuase as the engine warms the coolant expands. Once the pressure in the system is greater than the cap it is expelled into the recovery tank. Now, when the coolant cools down and contracts it's going to cause a vacuum and pull coolant back into the cooling system. Set-up as the above overflow tank, you will suck air into the cooling system which = bad. If you want to use an overflow tank it needs to be plumbed up like this. This allows coolan to be pulled back into the cooling system not air. It is far from ideal if your coolant gets dirty though becuase all the grit and nastiness will be the first to get pulled back into the cooling system. Regardless here is the schematic. Also... how are you going to fill that with coolant? :scratch: Throught the vent is about the only way. VERY difficult - ask how I know :tongue:

https://www.rx7club.com/attachment.p...1&d=1200016745

Here is the tank that I built. I have a nive cap to fill it, the fitting on the back is for the vent, the two on the side are for a sight tube, and the -4AN bung is welded onto the bottom.

http://forum.teamfc3s.org/attachment...1&d=1196265050
http://forum.teamfc3s.org/attachment...1&d=1196265050

ok im wanting to take that setup and instead of it being just open at the bottom to drain, it be a connected to the rad cap so the when the car cools down it will suck back in. your drawing is what it is supposed to do from the factory, the drawing i posted is what i want to turn it into....

Edit: Assumed he had an FD based on the sig. :icon_no2: time to go home.

wow posted to late.... thanks titanium for the info, it clears up the questions i had about the two designs.... im still looking to find a tank with a fitting on the underside of it and one up top so it can breathe

You don't have an overflow tank.... you have a recovery tank. They are two totally different tanks that have two totally seperate functions. & you are backwards about the way the coolant flows. As your engine warms the coolant is pushed out, as it cools it is pulled back in. It has nothing to do with the engine being on or off now would starting it create vacuum enough to pull coolant back in.

as for filling the tank up look at this one i found

http://www.2kracing.com/images/powersteeringtank.jpg

Guys - let me finsih posting :D

Now - I feel that the ideal recovery tank would look something like this. A vent to atmosphere on the top, a drain on the bottom, and a siphon tube to pull coolant back into it. I like the idea of a siphon tube becuase it won't let the crude that is in the cooling system get pulled back into the cooling system. The only thing this is lacking is a fill top. I didn't have the machinery nor did I find one to buy that could've replicated this. Plus I just know to stay ontop of my coolant as the engine is hauled every year or two anyways :rlaugh:

https://www.rx7club.com/attachment.p...1&d=1200017503

Expansion tank or AST (Air Seperation Tank)
 

This tank performs a function unlike any of the others. The sole purpose of the expansion tank is to trap air, and get it out of the system. It works like this, You plumb into the block/radiator, or both at thier highest point and route that to the side of the Expansion tank on an uphill run becuase air bubbles rise :shocking: The tank is there to catch the air but seeing as how there should be a flow, there should be a drain. A much bigger one (I'm using -10 - heater core size) needs to be plumbed from the bottom. This is plumbed into the lower radiator hose as that is the suction side if you will. It helps but is no necessary to have the first line in the pressure side of the T-stat.

The Expansion tank also has a pressure cap on it. If you are using a system like this, this spot needs to be the only cap that leads anywhere. If you have say a koya rad with a pressure cap - PLUG IT! The idea is the expansion tank captures all the air. As the coolant expands the air is forced past the pressure cap into the RECOVERY tank. The bubbles rise so the pickup is still submerged in coolant. When the coolant cools, coolant is pulled back into the system. If you were using an overflow tank, air would be pulled back in. Everyone understand? Here's a few examples and a few pics of the one I built.

https://www.rx7club.com/attachment.p...1&d=1200018034

Top fitting is after the pressure cap and goes to the recovery tank. Middle fitting is the inflow from the waterpump housing, bottom is the return to the heater hose.
http://forum.teamfc3s.org/attachment...1&d=1196736086
http://forum.teamfc3s.org/attachment...1&d=1196736542

I'm done posting for now ;) Ask away - there are usually questions

thanks for the info, i see how the tube pick up would be good as far as dirt and grime its just a matter of finding a universal one that has that, if i had my own house and tig i would do what you did and build one.... guess one day. thanks for the info this was alot more explained than what i found through searching

Thanks - It's been asked alot - archive maybe?? :dunno:

The pickup tube is nice - although certainly not essential. Even the one you posted a pic of earlier
http://www.2kracing.com/images/powersteeringtank.jpg
Wouldwork just fine. Plumb the top one to a drain tube outside the engine bay and the bottom one to the pressure cap and problem solved. Check out Canton Engineering right here in CT. They have a ton of tanks that you might be able to use. If you wanted to get really trick you could cut those two nipples off and thread them 1/8 or 1/4" NPT and thread in some "T" fittings. This would allow you to put a sight tube in, still maintain the ventedness :rolleyes: and have a p/u that wasn't at the bottom. The only drawback I see - no drain

actually i found this, it is cheaper has the sight tube in it and i can install a pickup tube from the right side

http://us.st11.yimg.com/us.st.yimg.c...1980_283220426

oh yeah and after 2 hours of sifting through the searched threads on this topic i would also say archive this thread because you went into depth about all three setups

Hit the little "!" in the original post (#1) and ask for it to be archived. Make sure you give a reasonable explanation as to why it should be archived and edited (to get rid of the junk like my posts).

Yeah but that one won't work unless one of the other two nipples has a siphon tube on it. Other wise its just a fancy overflow tank.... actaully - it doesn't even have a drain on it. I wouldn't get that one.

well the nipple on the right side is threaded, i thought about removing that and installing my own siphon tube, that way i have the sight tube, the middle one to vent it out and the right side one with my own personal tube i put in

Or just plug it and drill into the bottom. If the material is too thin you can have bung welded on dirt cheap or do the "T" trick with the bottom sight glass fitting.

This is really good info!!!

This looks like the stock design. Sorry for the noob questions, but I'm trying to learn something here. So, where exactly does this design drain to? The stock recovery tank doesn't have a drain.

It seems the stock tank is more of a resivor, but it also recovers. I'm a bit confused.

it drains to a bucket when you want to clean it out (when you change your coolant)

while this might not be the ideal setup,, for $50 it would be worth buying and at least messing around with

The stock tank is a recovery tank. The recovery tank works to store the excess coolant as it is expelled from the cooling system via pressure from the expansion of heating it. When the coolant cools it contracts and pulls the coolant back into the system. The stock piece IIRC has a cap that has a siphon tube going down to the bottom. That same cap also has a hose that just sorta falls off to the side, that is the vent/overflow (I don't like saying overflow becuase it's confusing enough with 3+ different types of tanks) If you were to fill the cooling system to the max, fill the recovery tank to the max and start the engine, as the coolant warms it's going to get pushed right through the vent/overflow tube. Alot of times people will have a small pin hole leak, a bad cap seal, or the barbs are leaking a little. What happens is as the coolant cools it pulls in outside air from these incredibly small places that when hot sometimes expand and seal not leaking coolant. Someone checks the recovery tank and it is full, but they crack the radiator cap and it's low. Naturally they add coolant to the radiator and now the system has slightly more coolant than it did yesterday. This cycle continues until the system is overfilled and spitting coolant on the ground through the vent.

Yes that WR thing could be mad to function properly VERY easy. The only two concerns for a recovery tank to work properly is a vent, and the source from the pressure cap must always be in coolant. Whether this is done with a siphon tube or by plumbing it into the bottom of the can it will work just fine.
If the tank isn't vented your cooling system will be under too much pressure
If the source from the cap isn't in the coolant at all time, you run the risk of pulling air back into the system

FWIW - my vent runs along the framrail and exits where the AC drain was :icon_tup: No coolant on hot turbo's for me.

Exactely. There is no drain on the stock recovery tank. Come to think of it, I've never seen a stock recovery tank wil a drain.

So would the ideal setup be a recovery tank or an air seperator tank?

I think air separator so you can reduce the likelihood of overheating/damage due to air in the cooling system.
FEED's $600+ AST for the FD:
http://www.neweraparts.com/Default.a...D=183&tabid=54
http://www.neweraparts.com/DesktopMo...jpg&PORTALID=0

$600 :shocking: I'll sell you mine for $400 and you won't need to make your own lines :rofl:

yeah, it's the same thing you're making but MORE expensive cuz it says "Fujita Engineering"

Either way you are going to need a recovery tank. Even with the expansion tank the coolant is going to get pushed past the pressure cap and needs a place to go. It has to go into a recovery tank otherwise it will be lost. I've heard of problems with some guys always getting air pockets in thier cooling systems. If you are one of those guys I would suggest using an expansion tank BUT you will still need a recovery tank. If you don't get pockets, don't bother and the stock system is fine.

Having said that an expansion tank will always be better than NOT having one. It's a little extra plumbing but at the end of the day it performs a very good function. If I were doing my FC over with an FC waterpump housing I would think very hard about where to put one, and just do it. But since I'm using the FD housing and the FD had one from the factory, the decision was a wee bit easier.

So if I were to rebiuld a T2 engine or what not, it would be ideal to use and FD waterpump housing instead of the stock one because FD's already have a stock ast, right? I learn something new everyday.

Now what about the oil. I've seen some products just like this, but made for the oil system. What's that about, or am I just mistaken?

You don't need to use the FD waterpump & housing and if you do I believe you will loose the AC & PS. I'm saying I did becuase the water outlets/inlets were in a betterplace. If you modified the t-stat housing you could pull a line off of that really easily to plumb into an expansion tank. Hell you could even keep the stock recovery tank if you wanted.

FD's HAD the AST which was why I didn't even think about whether or not I wanted one. But if I were to us an FC waterpump housing, I would probably modify it to accomdate an expansion tank.