Header Tank.

[V Mad]

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I would say thata header tank needs to perform these basic functions to work properly

1. Have an adequatereservoir of water (above the radiator top)

2. Have a flow and return system to enable air to escape to the top efficiently and allow mixing of any top up antifreeze or water

If you simply raise the original bottle this does not perform the second function.

Why do you need to modify the rad to get a return into the system? Why not braze a hose connection onto the metal hose tube or fit a tee piece into the heater returncircuit?

[jleyton]

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HiChris,

Re your "Have a flow and return system to enable air to escape to the top efficiently and allow mixing of any top up antifreeze or water" - I quite agree.

But surely with regard toair escaping then, if anything, the one-pipearrangement would reduce the possibility of airlocks and any air would tend to rise to the highest point - now at the top ofthe raised header tank (rather than hidden in the top of the rad or somewhere in extra pipework)

As fortopping up with water/anti-freeze,if small amounts were added to the header tank they would slowly mix via normal water movement and if larger amounts were added Eg coolant change, then you would be doing thisin the normal way via the filler plug which would allow sufficient mixing.

I think this, plusthe satisfactory reports given by mjheathcote and RobM will encourage me to try this simple way of doing it !

Cheers

Julian

[V Mad]

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You could try it but it IMO it is not as good as a flow system which you see on all modern cars surelyfor good reason?

If you use the standard expansion tube on your radiator as the only connection, the top of the tube will be a high point andany air will collect there rather than get to the bottle. Supposing you get an airlock in the tube, and this prevent the coolant from topping up the rad, then your engine could overheat!

With no flowthroughthe bottle and hoses, air and sedimentis more likely toget trapped in the system.

[Guest]

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V Mad wrote:

You could try it but it IMO it is not as good as a flow system which you see on all modern cars surelyfor good reason?

If you use the standard expansion tube on your radiator as the only connection, the top of the tube will be a high point andany air will collect there rather than get to the bottle. Supposing you get an airlock in the tube, and this prevent the coolant from topping up the rad, then your engine could overheat!

With no flowthroughthe bottle and hoses, air and sedimentis more likely toget trapped in the system.

Hi Chris, if I cut off the downturn on the left end of the copper expansion pipe, surely the increased pressure of a running engine would deal with any air ? or, block it and tee off the top hose. I'll happily accept that I'm being a bit thick, but I can't follow your logic, as any trapped air expands, wouldn't it push the water ahead of it onthe short rise to my tank ?

[V Mad]

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I cant see how you can physically avoid there being a high point in the pipes unless you haveyour expansion bottle fitted above the bonnet. Your car would look like a patient on a drip

We really need to have to have a pub debate on this as its difficult to explain using messages. Pity we are not local

[DJT]

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The standard radiator expansion pipe extends down into the radiator about 1-1.5" in order that it will still act as a syphon to suck back the expansion bottle contents on cooling. (Withoutopening up a previous discussion on thermo-dynamics, that is how I visualise it works).

As such, using this pipe in conjunction with a header tank won't be as efficient as fitting an aditional connectionpart way down the radiator to supply the head,and either tee-ing into the top hose or fitting another spigot to the filler plug housing to provide the air return, in the way that Steve's (Stagdad) drawing depicts.

IMHO

Dave

[Guest]

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V Mad wrote:

We really need to have to have a pub debate on this as its difficult to explain using messages. Pity we are not local

Now there's a thought ! Would you say that Steve's drawing covers what you're saying ? I'm still puzzled by my previous setup drawing air back into the rad. :? M.

[iani]

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Martin Stevenson wrote:

V Mad wrote:

We really need to have to have a pub debate on this as its difficult to explain using messages. Pity we are not local

Now there's a thought ! Would you say that Steve's drawing covers what you're saying ? I'm still puzzled by my previous setup drawing air back into the rad. :? M.

Martin, I have modified my rad and have 2 connections to my V70 expansion bottle, this setup works perfectly and you're more than welcome to have a look on Wed evening.

Ian

[V Mad]

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Martin Stevenson wrote:

V Mad wrote:

We really need to have to have a pub debate on this as its difficult to explain using messages. Pity we are not local

Now there's a thought ! Would you say that Steve's drawing covers what you're saying ? I'm still puzzled by my previous setup drawing air back into the rad. :? M.

Yes Steves drawing shows a working sytem but you can tap in anywhere across the flow and return circuit, even across the heater pipes!

[Guest]

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Thanks Chris, I'm hoping to get an aluminium radiator, and I'm very reluctant to make any permanent alterations, perhaps use the overflow pipe for the upper, and tee off the top hose for the lower ?

Ta Ian, see you at t'pub. Martin.