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Thread: Coolant expansion bottle Q

  1. #1
    Bodger

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    Coolant expansion bottle Q

    Hello, i run an S2000 engine in a mk2 rally car. I need to fit an expansion bottle to the coolant system, am I right in saying that I need to get it as high as possible and with as short a hose from the rad cap as possible. ??
    Also I have a competition aluminium rad with a competition cap, is there anything else that I need to bear in mind, as these are obviously not standard Honda parts.
    Thanks in advance for any help guys n gals.

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    Bodger

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    Coolant expansion bottle Q

    I'm not running an expansion tank buddy so I'm not sure. I didn't want to clutter my engine bay so I'm running waterless coolant instead, No need for an expansion tank that way 👍🏻




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    Bodger

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    Re: Coolant expansion bottle Q

    No need for expansion tank with waterless coolant, ? do u mean you run on pure antifreeze ? tell me more

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    Spanner Monkey haz87's Avatar

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    Re: Coolant expansion bottle Q

    Imagine it will be this

    http://www.evanscoolants.co.uk/

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    Re: Coolant expansion bottle Q

    Are you referring to a simple expansion/overflow bottle, or a remote pressurised header tank ?
    9.85 @ 145mph 202mph standing mile

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    Racer

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    Re: Coolant expansion bottle Q

    Two ways of solving the same problem - a) Using a normal rad with a normal rad cap you have a non pressurised expansion bottle which can be fitted anywhere - above or below the rad neck and b) Using a normal rad with a plain cap (ie no spring) and a pressure capable bottle that can have a trad. rad type cap or a non venting screw down cap. The former has a small dia pipe connection to the bottom of the bottle always under water so when coolant expands it vents out of the rad into the bottle, air bubbles out and level rises, when engine off and coolant contracts the water is drawn back into the rad keeping it full. With a pure pressurised header type tank it needs a fairly large dia hose connection and is best fitted to be the highest point. Air won't vent out of the system wholly but collects at top of tank. Modern systems are generally like this due to maintenance free aspect. Remember either system needs only ONE or NO pressure cap - multiple spring rad caps work against each other.........
    or use Evans Waterless coolant (as i'm planning to do) Plain rad, no spring cap and nothing else so very clean install.

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    Re: Coolant expansion bottle Q

    He hasnt actually stated a problem though ? just that he wants a bottle of some sort.
    9.85 @ 145mph 202mph standing mile

    https://www.youtube.com/watch?v=Ss_c7fML3rw

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    Bodger

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    Re: Coolant expansion bottle Q

    Thanks for the help lads, the only reason im doing this is, when she got a bit hot on the dyno she spat out a bit of coolant, she'll b under d same pressure on a rally so, I would have thought id be better having the expansion bottle.

    So to summarise what Katana said, just use my one pressure cap on the rad and a plastic cap that doesnt thread down on the expansion bottle and all should be good ?

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    Re: Coolant expansion bottle Q

    It would be helpful to now exactly what rad cap you have, and any fittings in that area.

    So it is just a basic overflow bottle you want ?

    If so, you'd need a cap that has 2 seals and can allow air/water to be pulled back in during cooldown if any has been ejected.
    9.85 @ 145mph 202mph standing mile

    https://www.youtube.com/watch?v=Ss_c7fML3rw

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    Re: Coolant expansion bottle Q

    Quote Originally Posted by escort outlaw View Post
    Thanks for the help lads, the only reason im doing this is, when she got a bit hot on the dyno she spat out a bit of coolant, she'll b under d same pressure on a rally so, I would have thought id be better having the expansion bottle.

    So to summarise what Katana said, just use my one pressure cap on the rad and a plastic cap that doesnt thread down on the expansion bottle and all should be good ?
    When i fill mine up it spits out coolant untill it finds it's own level aslong as it isn't throwing loads of water out and over heating it will be fine.

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    Racer

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    Re: Coolant expansion bottle Q

    @ Stevie - Problem wasn't the right word but fitted with my idiot vocabulary LOL!

    As long as the hose connection on either bottle type is under water - air will vent to top of bottle but won't be drawn back in so retaining max water content in the system.

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    Re: Coolant expansion bottle Q

    Rad cap needs to be of correct type to allow water to be ejected, and drawn back in...

    But it does depend if it's spitting out from a problem, excess heat...or it is simply finding its own level. Depends on other aspects of the system whether that's ok or not
    9.85 @ 145mph 202mph standing mile

    https://www.youtube.com/watch?v=Ss_c7fML3rw

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    Bodger

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    Coolant expansion bottle Q

    As above earlier.

    I use Evans waterless coolant (the one formulation for aluminium engines). no pressure on the system at all, can remove the cap at temperature and it's fine.

    The only downside is your engine tends to run a few degrees hotter, but micro boiling around cylinder walls is completely eliminated.

    Also no no need for any expansion bottles of any kind.


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    Re: Coolant expansion bottle Q

    That localised microboiling is intentional in modern engines, despite what evans marketing spiel may tell you, it's the best way of rapidly taking heat away from hotspots. Not only is eliminating it not a good thing, it's a double whammy as the evans stuff doesn't take heat away as fast as normal coolant without it either, which is why it runs hotter.

    Also, the coolant still expands from the temperature change, pressure or not, so you still need somewhere for expansion.
    Last edited by PhillipM; 12-06-2016 at 01:31.

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    Re: Coolant expansion bottle Q

    FWIW I'm running a pressurised header tank as high as I can get it in the engine bay, cap in the radiator welded up with a fitting to take the hose from the tank and the pressure cap on the tank, that means I can use the full cooling capacity of the radiator all the time instead of having the level rise and drop from using it as the expansion tank too.
    Last edited by PhillipM; 12-06-2016 at 01:41.

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    Re: Coolant expansion bottle Q

    I would dispute that as nonsense.

    If water does boil and steam is produced, almost no effective cooling or heat removal will take place. Steam is an absolutely shite conductor of heat, whereas water is great.

    The fact some systems are designed to run at higher pressures with water, are to prevent the water boiling anywhere in the system, and why many cooling systems are designed to self bleed in case steam is ever produced, to get it removed to the header tank as quickly as possible because air/steam in the system prevents it doing anything beneficial at all.

    Everyone knows what air locks can do ! Cause all sorts of headaches.
    9.85 @ 145mph 202mph standing mile

    https://www.youtube.com/watch?v=Ss_c7fML3rw

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    Re: Coolant expansion bottle Q

    No, it's to prevent mass boiling of the coolant, not to prevent it everywhere - in fact, if it did prevent it everywhere, why would you be worried about it? You'd also never worry about water pump cavitation but that happens too.
    Self bleeding is just an ease of maintenance thing these days mainly - it's still a closed system, anything flashing to steam will convert back to water, it doesn't stay as gas - nucleatic cooling in small area's is not an issue (in fact it's common, very common, around exhaust valve seats in the majority of engines, even ones designed without it specifically in mind) so long as it's taken away by the flow fast enough, converting water to steam takes ~7 times the heat away from the area that just heating water the same amount does.

    Before you tell me I'm talking nonsense out of hand because you don't like it, go on google acedemic, type it in, read about 90 papers on vehicles and research into using it first, there's also a good paper on the Renesis being designed floating around that goes into quite some detail on it as part of keeping the chamber cold (being continuously heated in one spot all the time means heat transfer is an issue).
    And of course the other god-knows-how-many papers from it being used industrially for decades before that in pressurised water cooling systems. It's even been used unintentionally for a long time in vehicles just as part of the normal 'rule of thumb' cooling design systems.
    Last edited by PhillipM; 12-06-2016 at 21:17.

  20. #18
    Bodger

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    Re: Coolant expansion bottle Q

    Thanks for all the opinions lads, the cap I have is a "STANT 18-22lbs" I noticed the spring was gone quite rusty,

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