bigandy
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| posted on 20/11/07 at 09:05 PM |
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Expansion tank plumbing...
Evening folks.
On a sealed expansion tank type cooling system in a car, where should the inlet and outlet of the tank be plumbed into? I am thinking that the inlet
to the tank (i.e. fed into the top of the expansion tank) needs to go at a high point in the cooling system (such as the rad top hose).
The outlet from the expansion tank (i.e. at the bottom of the expansion tank) then needs to be fed into somewhere, but is this critical for correct
operation? I am thinking that perhaps the bottom hose from the rad would do the trick, but I'm not sure.
Secondly, is there a correct way to fill a cooling system from completely empty?
Cheers
Andy
Dammit! Too many decisions....
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Michael
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| posted on 20/11/07 at 09:13 PM |
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I was asking the same at work. Have a Astra Expansion bottle wanting to plumb into Crossflow system.
Been advised i cant do what i planned.
So would depend on your engine etc.
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mark chandler
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| posted on 20/11/07 at 10:42 PM |
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I have a different approach that allows the tank to be low, you only have one pipe.
At the highest point in the cooling system take one small tube 1/4" ID, this is plumbed to the bottom of your header tank, thats it.
As water expands the header tank fills, as it cools the water is sucked back leaving air, you can now place this header tank anywhere.
My header tank is a bit of 2" ali tube, 8" long, bottom end capped with a standard rad cap on the top.
This is essentially the same system used on classic Range rovers, SD1 rovers etc, in these instances the header tank is plumbed off the top of the
rad, this has no eaxpansion top but a filling point.
Regards Mark
Regards Mark
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nitram38
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| posted on 20/11/07 at 11:04 PM |
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quote:
Originally posted by mark chandler
I have a different approach that allows the tank to be low, you only have one pipe.
At the highest point in the cooling system take one small tube 1/4" ID, this is plumbed to the bottom of your header tank, thats it.
As water expands the header tank fills, as it cools the water is sucked back leaving air, you can now place this header tank anywhere.
My header tank is a bit of 2" ali tube, 8" long, bottom end capped with a standard rad cap on the top.
This is essentially the same system used on classic Range rovers, SD1 rovers etc, in these instances the header tank is plumbed off the top of the
rad, this has no eaxpansion top but a filling point.
Regards Mark
Regards Mark
How do you fill the system?
Get an expansion bottle. It should have a small pipe at the top and a slightly bigger pipe at the bottom.
Not only are you looking for expansion, but a flow of water through the bottle.
This helps remove air from your system and aids filling it up.
The bottom larger pipe goes to a tee in you lowest hose. This is the one that returns from the rad to your engine.
The smaller hose needs to go anywhere on the highest part of the head or radiator hose from the engine.
It also depends on your engine set up, but on mine I have a small bleed hose from the top of my rad and from the top of my k-series head which join
together before going into the top of the expansion bottle.
The bottle also needs to be the highest point in your system for filling and air removal.
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mark chandler
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| posted on 20/11/07 at 11:17 PM |
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You have to fill at the high point, not the expansion tank, the point is that the tank can be low. On Range rovers, circa 89 - 93 you had an
additional filler which comes up by the middle of the plenum.
Where you have an inlet and outlet the tank must be high.
Okay, lets look at this another way take an older car with the expansion tank as part of the radiator, all we are doing is relocating the top part, by
using a small pipe you can bubble off the air.
This will fail unless you take the air out at the very top of the system, flow is unaffected, you must use a small diameter pipe, a large diameter
pipe will tend to try and act as the expansion tank itself.
[Edited on 20/11/07 by mark chandler]
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nitram38
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| posted on 20/11/07 at 11:24 PM |
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How do you maintain the correct amount of air in the expansion tank?
There needs to be some air to be compressed when the water expands.
[Edited on 20/11/2007 by nitram38]
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mark chandler
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| posted on 20/11/07 at 11:27 PM |
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Make sure it is large enough, a RR tank holds around 1 pint, you need to ensure when cold and the water is drawn back the inlet pipe remains covered
or you will start pulling in air.
On my blade engine I get around 1/4 pints worth of expansion, you only partially fill the bottle.
[Edited on 20/11/07 by mark chandler]
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craig1410
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| posted on 21/11/07 at 01:16 PM |
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quote:
Originally posted by mark chandler
Make sure it is large enough, a RR tank holds around 1 pint, you need to ensure when cold and the water is drawn back the inlet pipe remains covered
or you will start pulling in air.
On my blade engine I get around 1/4 pints worth of expansion, you only partially fill the bottle.
[Edited on 20/11/07 by mark chandler]
This is how I am doing it on my Rover SD1 engine and in that case I am using the SD1 expansion tank so I know it is the correct size. Yes, filling the
system was a slight pain but I just filled it via the radiator top hose until it was almost full and then just finished it off using the expansion
tank held up high (like a hospital drip) with the small hose removed from the inlet manifold to allow air to escape. This is in fact the highest point
of the system so I could be pretty sure that the air was all gone.
Now it is full I have connected the bleed hose from the top of the radiator to the one at the top of the inlet manifold to a t-piece and these both go
to the bottom of the expansion tank. Any air will bubble off here and then during the cooling cycle it draws coolant back in to fill the space once
taken by the air.
If you have an expansion bottle with two connections then it needs to be installed so that the level mark is at the correct level in relation to the
engine coolant level. On my car this would probably require another bonnet bulge...
Seems to work.
Cheers,
Craig.
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nitram38
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| posted on 21/11/07 at 01:25 PM |
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Wouldn't the set up I suggested be less hassle?
All I did was fill it up and go. It is self bleeding and replenishes the water continuously, plus I don't have to unbolt it at the side of the
road if I have to refill the system.
It might be another tee and some extra pipe, but the maintenance time sure outweighs the extra install time.
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twybrow
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| posted on 21/11/07 at 03:19 PM |
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I am using an expansion tank, which get fed from an outlet just below the filler/pressure cap. As the water expands in the system, it will be forced
up the pipe into the tank as previously mentioned. If I have filled it too much with water, then some will be chucked out through the filler/pressure
cap to give the correct pressure throuighour the system. It only has to do it once, then it will be correct level forever more! Simple.
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bigandy
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| posted on 21/11/07 at 03:27 PM |
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Hi folks.
I have to admit, I do prefer the idea of a self bleeding, easy to fill up system, and the 2 pipe option seems to be best so far.
On the 4a-ge engine I have, there is an 8mm pipe connection on the hose going to the water pump inlet, and an 8mm connection on the hose coming from
the head (i.e. waterpump outlet, to rad top hose). I'm thinking that I could utilise these connections for a two pipe expansion tank, and save
the need for T pieces etc.
The connections were originally routed to the stock throttle body, but as I won't be using that, they were going to be blanked off.
Now, to find a suitable expansion tank!
Cheers
Andy
Dammit! Too many decisions....
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bigandy
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| posted on 26/11/07 at 09:33 AM |
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Hi all,
I had a look unde rthe engine cover of an MR2 yesterday evening, and the expansion tank is of the single pipe variety.
The overflow from the filler cap (in the top hose, near engine) is fed into the bottom of the tank (via the plain filler cap). There is a vent on the
top of the tank too.
I still prefer the two connection type though... 
Cheers
Andy
Dammit! Too many decisions....
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craig1410
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| posted on 27/11/07 at 08:45 AM |
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quote:
Originally posted by nitram38
Wouldn't the set up I suggested be less hassle?
All I did was fill it up and go. It is self bleeding and replenishes the water continuously, plus I don't have to unbolt it at the side of the
road if I have to refill the system.
It might be another tee and some extra pipe, but the maintenance time sure outweighs the extra install time.
Maybe but I stuck to the principle of using the same system as was employed on the donor car. My concern was that if the expansion tank wasn't
at the right height then with a two connection system it won't tend to work correctly.
Also, with the single connection system like mine, it wouldn't be difficult to add in a separate filling point if you plan to refill your system
regularly.
Cheers,
Craig.
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