Expansion Tank

[NickL]

Whats the purpose of it? A place to fill/have the cap incase the system over pressurizes? I want to delete it in my car. Don't tell me to run an M42 radiator because thats what I already have, ill be using a completely different radiator with no expansion tank and I don't want to have one mounted in the bay.

Can I plug the port on the spider hose and just let coolant circulate without it?

1 of the 2 ports is already plugged as I bypassed my throttle body heater lines.



I would have an inline filler neck like so



And possibly could run an overflow style rad with a catch can style overflow tank?

Im just trying to put something together but I'm not sure the exact purpose of the expansion tank and want to learn about it more to see if deletion of it is possible. Thanks!

[NbAmTwE]

so let's use your M42 radiator as an example to explain somewhat of my understanding as to why you NEED an expansion tank for a radiator designed to utilize one. These engines are designed to run a pressurized cooling system that will be directly running through the radiator. Now these radiators are designed to be using an expansion tank, hence it is mounted directly on. This is because as the coolant expands in the system, which is why the overflow doesn't getting filled but half way, we don't increase our pressure in the cooling system; causing nasty leaks and creating damage to cooling components (hoses, etc.).
So with my understanding, if it's correct, you can swap radiators to something designed to utilize a catch can tank or other cooling system applications that aren't normally found in BMWs designs. It's the particular radiator you use and what it relies on that matters.
Are you going to an e36 Mishimoto or something; if so be aware that the E36 cooling design and therefore the radiator itself relies on implementing an expansion tank.

I hope my information is correct and hope to see others chime in to either correct or add to what I've said.

[vaughnbannister]

if you don't want the expansion tank in the bay look at the 318is radiator. the 318is radiator has the expansion tank connected to the radiator itself so no expansion tank needed in the bay, it is a much cleaner look.

[Mr. Tasty]

Don't tell me to run an M42 radiator because thats what I already have, ill be using a completely different radiator with no expansion tank and I don't want to have one mounted in the bay.




!

if you don't want the expansion tank in the bay look at the 318is radiator. the 318is radiator has the expansion tank connected to the radiator itself so no expansion tank needed in the bay, it is a much cleaner look.

how about fucking reading

[NickL]

so let's use your M42 radiator as an example to explain somewhat of my understanding as to why you NEED an expansion tank for a radiator designed to utilize one. These engines are designed to run a pressurized cooling system that will be directly running through the radiator. Now these radiators are designed to be using an expansion tank, hence it is mounted directly on. This is because as the coolant expands in the system, which is why the overflow doesn't getting filled but half way, we don't increase our pressure in the cooling system; causing nasty leaks and creating damage to cooling components (hoses, etc.).
So with my understanding, if it's correct, you can swap radiators to something designed to utilize a catch can tank or other cooling system applications that aren't normally found in BMWs designs. It's the particular radiator you use and what it relies on that matters.
Are you going to an e36 Mishimoto or something; if so be aware that the E36 cooling design and therefore the radiator itself relies on implementing an expansion tank.

I hope my information is correct and hope to see others chime in to either correct or add to what I've said.

Makes sense. I will not be using an BMW styled radiator anymore. I will be using a general inlet/outlet with a cap/overflow. Like a honda. So looks like ill go ahead and give it a try.

[AndrewBird]

You HAVE to have an expansion bottle. When coolant gets hot, it expands and needs someplace to go. If it doesn't have anywhere to go, you are going to blow a hose or worse.

[ParsedOut]

how about fucking reading

Hahahahaha, little on edge today Cody? I thought it was pretty damn funny myself.

[NickL]

You HAVE to have an expansion bottle. When coolant gets hot, it expands and needs someplace to go. If it doesn't have anywhere to go, you are going to blow a hose or worse.

So then how does every other car with out an expansion tank work? Doesn't it just flow into the overflow?

[NickL]

Bumping this because I need to know if the S52 can run on a non pressurized system. Simple cap/overflow system.

[10Toes]

You HAVE to have an expansion bottle. When coolant gets hot, it expands and needs someplace to go. If it doesn't have anywhere to go, you are going to blow a hose or worse.

No, if he runs this with a std. radiator cap that bleeds pressure he will not have that problem.


The problem he will have is that the coolant expands and contracts so it will bleed off coolant when it is hot and then as it cools down it will contract and put negative pressure on the hoses. It will collapse the hose when it is cold, not sure what problems this would cause but could potentially cause cold coolant flow issues and add strain on the cooling system. Why is a expansion tank that bad?

[10Toes]

Bumping this because I need to know if the S52 can run on a non pressurized system. Simple cap/overflow system.

Doesn't the coolant need to be pressurized so it does not turn to steam at the temps that M50s are built/tuned to run at

http://eng-calculations.com/Saturated%20Steam.aspx/Saturated%20Steam.aspx

[FLG]

Yes you can run a non pressurized system, but youd need to run Evans coolant

http://www.evanscooling.com/

And now to clarify, an expansion tank is NOT required. But due to the design of the cooling system, youd would need something like 10toes posted up. For example, my old charger (and many classic cars for that matter) did not have an expansion tank. The radiator cap would bleed coolant at a certain psi (forget what it is off hand) when it was topped off/hot, the excess coolant would spill out, after this happened and all the excess coolant was removed, it would obviously be a bit underfilled when cold but would be at the correct level when hot.

Also 10toes, it will not be negative when cold and collapse hoses it will simply be at 0 psi. It would be like if you deflated a tire, its not going to create a vacuum.

[AndrewBird]

Ok, bit of confusion here. And expansion tank and an overflow bottle serve the same purpose and are essentially the same thing. Only difference is a overflow bottle is not pressurized. You need some kind of vessel to allow coolant to expand.

An expansion bottle has the cap built into it, so essentially, it is an extension of the radiator side tanks. This allows a pocket of air to be in the system to allow for expansion without causing problems like overheating due to an air block.

An overflow bottle is just a bottle. The radiator cap is on the radiator and an overflow line is ran to the bottle from the neck of the radiator (where the cap is). As pressure builds up, the cap opens and allows coolant to flow out, reducing pressure. As the coolant cools down, the cap opens in the opposite direction and sucks coolant back in.

The only way to run a non-pressurized system is to use the Evans coolant like FLG says.

[FLG]

Right. But you can run a system without the overflow bottle, when cold it would be underfilled by a bit when hot it would be at proper level.

Sent from my SCH-I545 using Tapatalk 2

[AndrewBird]

Doing that will allow air into the system, which can then cause problems. A warm engine would puke all the extra coolant out, but then as it cooled, it would suck air back in.

Even with an overflow bottle, you need to keep a bit of coolant in the bottle so the hose going into it isn't exposed to air.