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Author: Subject: Expansion Tank
Robster

posted on 10/5/07 at 12:27 PM Reply With Quote
Expansion Tank

This may be a really daft question, but i'll ask it anyway...

Is it necessary to have a coolant expansion tank?

I've got a 1300 XFlow, the rad is mounted such that the rad top is lower than the thermostat housing. I have replaced the standard thermostat houseing with one as below.

As the housing is above the rad, do I need to plumb in an expansion tank, or can I simply get away with blocking off the tank outlet on the new housing?

Thanks!
Rob.

[Edited on 10/5/07 by Robster]

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Robster

posted on 10/5/07 at 12:27 PM Reply With Quote
try again with the attachment...
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robertst

posted on 10/5/07 at 12:34 PM Reply With Quote
many people here dont use an expansion tank and have a closed circuit.
it is a pain in the neck though, to refill and level out without an expansion tank. plus the expansion tank lets u pressurize the system therefore increasing the boiling temperature of the coolant.

i myself am going to use an expansion tank. its so much easier to maintain and check periodically not mentioning the ease of maintenance





Tom

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RazMan

posted on 10/5/07 at 12:35 PM Reply With Quote
The expansion tank is neccessary imo but it is more important when initially filling the system, allowing air bubbles to come out, being replaced by coolant. My tank level does vary quite a bit between hot & cold and I would worry about the pressure variance in a system without an expansion tank.

Having said all of that, you could try running without one and see how it goes.





Cheers,
Raz

When thinking outside the box doesn't work any more, it's time to build a new box

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Gazza

posted on 10/5/07 at 12:44 PM Reply With Quote
I don't run an expansion tank on my 4AGE.

Apart from a bit of a pain to start with to ensure there was no air in the system its proved ok [500ish miles & 1 track day] - consistant engine temp and no loss of coolent.

Checking the coolent level means I need to remove the nose cone - but only takes a minute to do this so no problem.





Just a bag o' rusty spanners

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britishtrident

posted on 10/5/07 at 12:46 PM Reply With Quote
What type of rad do you have ?
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procomp

posted on 10/5/07 at 01:24 PM Reply With Quote
Hi given you are going to be racing it it is a must to fit the expansion tank.

Conect the air bleed from the rad if fitted to a T connection and also one from the small fitting on the thermo housing to the T conection.

Then run from the remaining T connection to the top of the expansion bottle. And the lower return from the expansion tank back to the fitting on the top of the water pump.

This will give you a fully circulating system and allow all air to find its way back to the header/expansion tank. It is how just about every one of the locost racers is plumbed up and is the proven working system.

Dont worry about the water outlet from the inlet manifold as it is never used.

A good source of cheap header tanks are from the vauxhaul range or the good old ford XR2.

cheers matt

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Robster

posted on 10/5/07 at 03:09 PM Reply With Quote
Okay, thought it would probably be best to have one... just seeing if I could get away with being lazy for now

Cheers!

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NS Dev

posted on 10/5/07 at 04:19 PM Reply With Quote
err well the laws of physics dictate that you need something to allow for the expansion of the water.

If you have decent rad hoses and no expansion tank, the engine will throw out water through the pressure cap until there is room for the expansion of the water, simple as that!

As a rough guide, you are talking about between 50ml and 150ml actual expansion volume on a typical car cooling system.

I have a very small expansion tank plumbed into the top hose on my setup, and if i overfill it it soon throws the extra water out for me, as 12psi (rad cap pressure) plus 95 deg c and a given volume of water will always take up the same space, which is more than the same water at 20 deg c.





Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion retro car restoration and tuning

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