Hi
I have a 1999 EM1, with the factory B16A2. I'm looking to install a Tegiwa radiator in place of the stock one, along with silicone rad hoses. To clean up the bay a little, I was thinking about removing the coolant expansion/overflow tank.

Now my usual understanding is, coolant expands, it drains into the overflow. When it cools and contracts, in a pressurised system the coolant is pulled back into the radiator. However, I don't think the civic EK uses a pressurised expansion tank? The hose goes from the rad cap, to the top of the tank, obviously draining coolant is fine. But the lid on the tank doesn't look like it's creating any kind of seal, so I can't see how the rad sucking coolant back into the system would work?

If it's not pressurised, and coolant isn't actually moved back out the overflow tank when the engine cools, then it's essentially just a catch can for coolant to stop it overflowing onto the road, right? So I figure if I leave the tank on, get the car as hot as possible, let it drain what it needs to drain. I should be able to safely remove the overflow bottle.

I wanted to consult the forum first, to see if anyone had done similar, or to see if I'm being stupid and it does in fact somehow move coolant from the overflow back into the rad.

I'd appreciate anyone's feedback, or tips.

Thanks

 

I tied the coolant bottle in front of the rad, to the left hand side on one of the metal supports and ran it daily(25miles a day) like that for a couple of years without problems, i bought a meter length of 6mm ID silicone hose to go from the bottle to the tank. It's obviously not that easy to get to, or see, if you're looking to see if you're losing coolant for whatever reason.

 

It very much pulls the coolant back into the system when the car cools off. It does this simply by drawing it back via the tube.

I'm running a Koyo with a CT Icebox, so I had the same issue. Solved it with an ED/EF Civic bottle and a bracket from a DC Integra (it might be the PS reservoir bracket, can't remember anymore):




You'll have to notch the bracket if you still have AC, otherwise it fits like it's meant to be there:

 

Not a bad idea, I'll have to see if that will work for me as I have an AEM V2 fitted that goes down to the left side of the rad already.

 

Hi, thanks, I did have a look and I don't believe mine even has the hose inside the expansion tank like it should - I see how it would work though, with a hose going to the bottom of the tank to draw coolant back into the radiator. This is quite a nice setup, although as in the above reply I have an AEM induction kit that would prevent me from doing this exact relocation. I may look into something similar though to clean things up a bit.

 

When I mean in front, I mean in front of the radiator, behind the bumper. The aem will be no where near it. Thats why it becomes very difficult to check levels

 

No it won’t. The AEM V2 goes down alongside the frame rail behind the rad, same as the duct on the bottom of my air box. It’s the whole reason that I put it where it is.

 

Ah, I see, that could be a good solution then. I'll have a look and see if I can do that today. Appreciate it

 

Sorry, yes, I'm being stupid. I may look into that relocation, it does look a bit tidier although I think I'd prefer it completely hidden if possible. Don't mind pulling the bumper off to check levels every now and then if need be. Thanks