Rb25 Coolant Flow / Hose / Swirl Pot / Header Tank Setup

[BlackBox]

So it looks like the go would be:

Blank radiator cap, Radiator Filler neck to top of header tank, hoses from intake runners to top of header tank
Then bottom of header tank to thermostat housing..

Would i still require an overflow bottle if the header tank is say 2Lt?

[NEO25T]

On 8/22/2018 at 9:39 PM, BlackBox said:

So do i tap a thread in the top of the runners and install bleed screws or maybe a swirl pot is the easier option? 

I dont have a close up pic but i put a plug in the turbo water return and 2 bleeders in the manifold

The idea was to slip some hose over the bleeders and connect to a bottle that can hang from the bonnet while bleeding the system, just to keep coolant from getting everywhere.

Havent thought too much about this lately as i dont have a running motor so dont really need to worry about how to plumb the water system up

[DiscardTheWeak]

20 minutes ago, NEO25T said:

I dont have a close up pic but i put a plug in the turbo water return and 2 bleeders in the manifold

The idea was to slip some hose over the bleeders and connect to a bottle that can hang from the bonnet while bleeding the system, just to keep coolant from getting everywhere.

Havent thought too much about this lately as i dont have a running motor so dont really need to worry about how to plumb the water system up

 

20 minutes ago, NEO25T said:

I dont have a close up pic but i put a plug in the turbo water return and 2 bleeders in the manifold

The idea was to slip some hose over the bleeders and connect to a bottle that can hang from the bonnet while bleeding the system, just to keep coolant from getting everywhere.

Havent thought too much about this lately as i dont have a running motor so dont really need to worry about how to plumb the water system up

Do you intend on using one of those spare fittings in the back of the thermostat housing for the bottom fitting of the tank? 

[NEO25T]

Ive only got a part time motor going in at the monent so will leave this alone for now.

I did tap the other one for a -12 fitting to go in so i dont have that fitting on the back of the thermostat housing any more, keep changing my mind how ill set it up

[BlackBox]

Is it ok to run the bottom of the header to the thermostat housing or does the header need to go to the bottom of the radiator? If so what do i do with the fitting on the thermostat housing

[DiscardTheWeak]

7 hours ago, BlackBox said:

Is it ok to run the bottom of the header to the thermostat housing or does the header need to go to the bottom of the radiator? If so what do i do with the fitting on the thermostat housing

https://www.pirate4x4.com/tech/billavista/Cooling/

Check out the article above. Its a good read about these system, not on our engines, but informative 

[NEO25T]

20 hours ago, BlackBox said:

Is it ok to run the bottom of the header to the thermostat housing or does the header need to go to the bottom of the radiator? If so what do i do with the fitting on the thermostat housing

It goes to a bleed point from factory so that might be the best place to run it

[BlackBox]

It goes to a bleed point from factory so that might be the best place to run it

You are saying the bottom of the header tank may be the best place? Or the factory bleed point? (which i dont have)
The barb on the back of the thermostat housing is only 3/8 and they say the bottom of the header tank should be fed by a hose 3/4 minimum..
I also cant find a header tank with 3/8 barbs on it and after playing around all day cant find a suitable location to mount a tank that would be high enough that clears my bonnet, plenum strut brace and theottle cable...

If once it is initially bled it will remain so then i am really in favour of just installing bleed nipples, as long as the cooling system doesnt release gas/vapour during driving?

[DiscardTheWeak]

4 hours ago, BlackBox said:

You are saying the bottom of the header tank may be the best place? Or the factory bleed point? (which i dont have)
The barb on the back of the thermostat housing is only 3/8 and they say the bottom of the header tank should be fed by a hose 3/4 minimum..
I also cant find a header tank with 3/8 barbs on it and after playing around all day cant find a suitable location to mount a tank that would be high enough that clears my bonnet, plenum strut brace and theottle cable...

If once it is initially bled it will remain so then i am really in favour of just installing bleed nipples, as long as the cooling system doesnt release gas/vapour during driving?

Are you installing this in a similar way as a “swirl tank”, ie the Greddy coolant swirl tank? In essence you are simply raising the highest coolant level above the height of the engine, so you can effectively maintain zero air pockets in the cooling system. The original radiator cap gets a dumb cap, and the expansion gets the pressure release cap at the new higher level. By running hoses from the highest point of the radiator (the old overflow nipple), and the highest point of the engine (the OEM bleed port) to the tank, you creating flow paths of liquid where air normally would get trapped. Correct if I am wrong on that portion....

The lower port on the tank in most systems I see gets tee’d into the lower radiator hose, which would effectively cause a “suction” or flow out of the bottom of the tank on an RB. Correct? Thus drawing in the coolant from the hoses connected to the head and radiator, creating a constant (kind of) flow in the tank, effectively creating a continuous air bleed. Now, the question of whether you can install the tanks “bottom fitting” before (lower rad hose) or after (behind the thermostat housing) is one I am still unsure of. However, in my mind it would be preferable to have it plumbed behind the thermostat, as the flow path be provided even when the thermostat is closed. Just like your heater core, which gets coolant flow with the thermostat closed. My guess that teeeing into the lower rad hose is for two reasons, one its easy to simply cut the hose  and install the adapter, two, you you really dont need its function until the thermostat would be open anyway. 

In many cases, with the amount of modification we do to these engines, we are left extra barbs and fittings in the coolant and air paths, leaving us creative options to add aftermarket components like this. In the case of the RB26 removing the factory oil cooler leaves you with two 1/2” barbs to work with. On an RB25, if I recall, I haven’t looked at mine in awhile, but there are extra fittings on the heater pipes on the back of the thermostat. As far as the size of the hose to use, I’d like to I know the answer the that question too, with a technical reason behind it. Reason being, the bottom fitting on the Greddy tank is not close to 3/4”, and the plumbing to factory expansion tanks is also not 3/4” either, so I am not sure where 3/4” came from. Check out the Radium Auto coolant expansion tank, and its installation instruction on the website. All of the fitting provided are -6, so in your case with a 3/8” barb behind the thermostat, I dont see why that wouldn’t work. 

[GTSBoy]

The pipework for these bleeder systems wants to be as small as will work, because the flow bypasses the main circuit, resulting in less flow where you would prefer it (radiator, engine, whatever is being bypassed).

[BlackBox]

The pipework for these bleeder systems wants to be as small as will work, because the flow bypasses the main circuit, resulting in less flow where you would prefer it (radiator, engine, whatever is being bypassed).

That makes sense, besides the bottom fitting which i imagine is where the coolant is returning to the system

[DiscardTheWeak]

5 hours ago, BlackBox said:

15 hours ago, GTSBoy said:

The pipework for these bleeder systems wants to be as small as will work, because the flow bypasses the main circuit, resulting in less flow where you would prefer it (radiator, engine, whatever is being bypassed).

That makes sense, besides the bottom fitting which i imagine is where the coolant is returning to the system

If my understanding of these systems, yes that would be return. To make the cooling system easier to trace, just use the heater core hoses as your guide. You know the water is drawn in from the thermostat are, so you can assume to call that IN, or suction, or return. Anything attached to that would also behave the same way, like the OEM oil cooler, or throttle body heaters, or turbo feeds/returns. 

[discopotato03]

I can't remember which way round it works , as in plumbing the swirl pots lower fitting to the bottom radiator hose or to the fitting pressed into the back of the blocks thermostat "bowl" .

I tend to think that the way to go is behind the thermostat rather than in front like Nissan has it standard .

While I'm here if anyone has that fitting that presses into the block from a Neo turbo engine I'm prepared to pay well for a good used one . Neo Ts are about 10mm here where the R33 and Neo NA are 8mm .

Cheers A . 

[Komdotkom]

[BlackBox]

Hey mate where did you get your header tank from?

[Komdotkom]

I made it myself.