Overflow bottle delete/ relocate

mx5002 · Postby **mx5002** » Thu Sep 24, 2015 9:02 am

I have gone on a quest to rid my engine bay of aged white plastic bottles.

Now does it's replacement have to be level with the top of the engine? I'm not sure whether one mounted lower would work (so long as there was fluid in it to submerge the overflow hose which goes into it or would gravity do it thing and just push the remaining fluid in the house into the bottle. But if it's sealed at the rad cap there wouldn't be any air /pressure to let it fall?

Thoughts?

Postby **beavis** » Thu Sep 24, 2015 10:50 am

I wouldn't want the top of the overflow to be below the top of the radiator as I'd suspect it would have a higher chance of overfilling and leaking out the bleed hole.

mx5002 · Postby **mx5002** » Thu Sep 24, 2015 11:03 am

It's kinda what I'm thinking also. I'm thinking a bottle directly next to the radiator in between the headlight and radiator is the go. Maybe something the size of an aluminium can would suit nicely in there

mx5002 · Postby **mx5002** » Thu Sep 24, 2015 11:31 am

Just picked this up from Coles. Thickest plastic I could find in a size that should fit nicely and be level with the top tank.

It even come with coolant in it :lol:

Mr Morlock · Postby **Mr Morlock** » Thu Sep 24, 2015 4:45 pm

if you are talking about OEM plastic containers like radiator overflow or windscreen reservoir then you might be better off replacing with like for like i.e. new and clean etc. If you start re engineering location points you may run into problems that the design engineers were already aware of. Whilst the last post was a joke virtually any of the plastic bottles used for domestic purposes are not suitable for OEM car applications because of the more extreme environment. Incidentally water does not flow up hill.

mx5002 · Postby **mx5002** » Thu Sep 24, 2015 8:03 pm

Your right water does not flow up Hill but doesn't the vacuum of the cooling system draw the coolant back in as the engine cools. And spews it into the overflow when it gets hot?

madjak · Postby **madjak** » Thu Sep 24, 2015 10:49 pm

I have a small aluminium overflow tank bolted to my passenger side chassis rail well below the radiator fill point. How I've got mine setup is a 1.1 bar radiator cap on the radiator and then the overflow linr running to the bottom of the overflow tank. This has a 1.3 bar cap on it.

I figure any air in the main system will expand and push out past the main cap to the overflow. When it cools it will suck back in coolant. It will only spill coolant if the total system gets past 1.3 bar and fills the overflow tank.

Seems to work well. Is light, cheap and has a low center of mass.

madjak · Postby **madjak** » Thu Sep 24, 2015 10:55 pm

Here is a photo when I was just setting it up. I needed space on the drivers side so had to do it. It doesn't have the radiator cap on the small overflow in this photo. I have also changed the nipple fitting to a 90 degree one so that the line fits better.

ndragun · Postby **ndragun** » Fri Sep 25, 2015 11:06 am

Gratuitous engine bay shot time;

There is a Moroso overflow tank available as a bolt-on-replacement, if you're that way inclined.

https://www.flyinmiata.com/moroso-coolant-overflow-tank-for-na.html

mx5002 · Postby **mx5002** » Fri Sep 25, 2015 1:43 pm

^^^^ if you have it flaunt it guys! Two of the nicest bays I've seen

I like the Moroso unit but yeah I want to hide it as much as possible. Madjaks setup is a nice one but the standard mx5 radiator doesn't suit that setup as well I guess I could double back with the hose though.

madjak · Postby **madjak** » Fri Sep 25, 2015 5:21 pm

mx5002 wrote:^^^^ if you have it flaunt it guys! Two of the nicest bays I've seen

I like the Moroso unit but yeah I want to hide it as much as possible. Madjaks setup is a nice one but the standard mx5 radiator doesn't suit that setup as well I guess I could double back with the hose though.

My engine bay? There is 25 years of grime covering most of the paint that I've tried to clean up with polish. You can only reach the exposed parts so one day I'll pull the motor and respray it properly. I'm also going to clean up the wiring harness and make that a single item. Gotta finish all my other projects first!

You could probably run it the tank down on the driver's side chassis rail. It was only $90 for that little Moroso tank and seems to works fine, not that I sit in traffic in my car. With the two pressure caps set up I don't think there is a risk of it siphoning due to gravity.