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Same as above
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Discussion Starter #1
Thinking of adding a pressureized expansion tank on my civic. Getting rid of the useless catch tank/overflow tank. Run a flat cap on the radiator. T off lower radiator hose to bottom of tank and normal overflow off radiator to top of expansion tank.

Advantages:
Being able to see level of coolant in the system.
Self bleeding.

Think of any disadvantages?
 

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Premium Member
88 RT4WD wagon
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the expansion tank has a vented pressure cap on it, you can even get these with a port to dump into an overflow(good for track tech sometimes.)
Been running mine with a scirocco rad for almost a year now, no issues. Just used the super common old 2 port VW one. shape is going to be the hardest part, you still want it mounted as the highest water location in the bay too.
You need a bleed port from either the bleed port on the block port or the top of the rad. then you feed the tank to the heater core return.

 

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Discussion Starter #4 (Edited)
the tank will have a pressurized cap same as oem radiator cap, with a nipple on the side. I'm thinking of using a tank from most late model cars. seems like they all have this setup now.

2016 Honda Civic.


2016 Dodge Journey, I like how clear this tank is.


Use a fitting like this on the lower radiator hose.


Cap like this to replace cap on radiator:
 

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Discussion Starter #6
This is almost exactly what I had in mind. Nice find on the radiator. is it completely sealed except for the radiator hoses? If that were the case you could use the bleeder fitting on top of the radiator hose fitting on the head to connect to the top of the expansion tank.
 

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This could be really cool! most of my older projects have been more rat-rod or "junk yard" style, running mason jars as over-flows and the like, but I actually like this concept for a little civic! post it up if you go for it!
 

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88 RT4WD wagon
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This is almost exactly what I had in mind. Nice find on the radiator. is it completely sealed except for the radiator hoses? If that were the case you could use the bleeder fitting on top of the radiator hose fitting on the head to connect to the top of the expansion tank.

its sealed except for the cap on the expansion tank, they make caps with a nipple to dump into an overflow tank if desired or required by your racing org incase you blow a headgasket and push fluid out. my radiator had another nipple up top which i assume is what it was originally use for. im sure you could use the top of the engine outlet if you wanted though.

you know what's awesome? not ever having to deal with bleeding the system to correct idle issues since the tank works like a swirl pot.
 

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Classic Man
Civic
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You shouldnt ever need to bleed the system with the OEM honda design unless you have a leak in the system.

As the pressure drops in the system from the temps coming down, there is a low pressure zone created in the rad, and the cap allows the system to suck fluid back into the cooling system at the highest point. If you ever see collapsed hoses on a car or truck, the cap is bad and wont let it suck coolant back in as it cools down.

Now lets say theres a leak, well the system will suck air in at that leak, not coolant in at the cap. And yeah you would have to bleed it all the time.
 

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88 RT4WD wagon
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i mean even the first time you fill it you don't have to bleed anything(not that it's difficult, just one less thing to do).....my motor comes out frequently due to various circumstances. Not a huge advantage or anything just a neat feature
 

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Classic Man
Civic
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I dunno man, BMWs come with that type of setup, and they are one of the douchiest cars to bleed, ever. Same with VW's. Easy to get air pockets that cause over heating. They even make "coolant evacuators" so you can pull the system down to -30inhg and then "suck" coolant into the engine to fill it, just for cars like BMWs and Caravans with the huge HVAC system, etc.
 

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88 RT4WD wagon
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fair enough. I've had no issues with mine, the top of the scirocco rad bleeds off into the top of the tank, bottom of the tank sucks down into the heater return on the pump intake side of the thermostat. it's not much different than a swirl pot with a rad cap on it. It's by far the highest point in my cooling system.

It gets rallycrossed frequently and if all that bouncing and rolling doesnt upset it i have no idea what would.
 

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88 RT4WD wagon
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i would cringe about touching a 2.slow period! haha. yeah the deathstar cooling tank thing looks waaaaay more complicated than mine. I would prefer to use a nice two port metal one from summit or something for a peace of mind on durability and ease of mounting but this one was 10 bucks.
 

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The pressurized expansion tank was the bane of our existence when we ran VW's. Lots of points to failure. In our little Honda rally car, we run an 20 oz. soda bottle overflow that has lasted 2 seasons. The price was right.
 

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the artist formerly known as drexelstudent11
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Have you looked under the hood of a honda in the last decade?
yeah, I've looked at a few in detail.

none of them had D series motors though, so I don't see how they're relevant :whistling:
 

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why re-engineer the Honda system that works great as it comes?
#1. because racecar, make it work reliably, cheaply, and easy to replace.

#2. (for me anyway) because i ended up doing the tucked scirocco radiator for a full width that didnt take up any more bay space. So my options were this or figure out a place to add a filler neck. I didnt have to pay anyone to weld something up for me for this and it was about as cheap and works just as well as an inline filler neck in my situation.

I dont think anyone would just go doing this to do it, or at least i hope you wouldn't. And for any sort of tracking purposes you'd still need an overflow in addition to this or it probably wouldn't pass tech. most organizations don't like spilled fluids.
 
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