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Expansion bottle for radiator


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#1 kavesh

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Posted 26 February 2023 - 09:09 PM

Hello everyone

 

I'm sure many have considered and installed expansion radiator bottles on your Holden 308s.

 

Now I don't have any issues with overheating, but I don't like the idea of my coolant level staying about half way down the on the radiator looking through the neck. I don't loose any coolant at this level.

 

I like the idea of having that extra half a litre or 1 litre of coolant in the system which is why I am thinking of it.

 

Would appreciate any advice on the matter and pics would be great as well.

 

Thanks in advance

 

Kavesh

 



#2 rexy

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Posted 28 February 2023 - 03:29 PM

Do you want shiny or boring standard plastic?

 

Attached File  9BE7A37F-F43F-46E5-99C1-5B860362D50C.jpeg   417.16K   4 downloads

 

Shiny is best.



#3 Bruiser

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Posted 28 February 2023 - 06:40 PM

I can understand why that water level seems weird, but If you don’t have a problem with running temperatures, why are you worrying?
Maybe you could check out a system from the mid 80’s with a coolant tank setup.
I have a 1985 commodore with a plastic coolant reservoir on the upper inner guard/ shock tower area
higher than the radiator cap and overflow outlet
Probably a common setup for that time period, Just the next factory development phase from yours.
South African cars must have followed suit in that era with similar setups,
perhaps you could find one over there you could duplicate,and acheive
the coolant level you want to see?
Check with a radiator system guy first, there’s more to this than meets the eye
To quote the yanks, (but probably the wisest thing they’ve ever said)
If it ain’t broke, don’t fix it

#4 76lxhatch

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Posted 01 March 2023 - 03:47 AM

If you're doing some weekend racing it may be a requirement to capture overflow.

 

Also difficult to get a non-recovery cap so doesn't hurt to use it. Doesn't have to be higher than the radiator cap (the tube at the bottom of the tank rarely is) but shouldn't be too low or the coolant may not recover properly.

 

I had a factory plastic tank until recently but they're marginal in size for a bigger radiator so made up a slightly bigger one.

20230107_152921.jpg



#5 Bigfella237

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Posted 01 March 2023 - 09:14 AM

~ I don't like the idea of my coolant level staying about half way down the on the radiator looking through the neck. ~


Remember that's only when it's cold. At operating temperature the coolant will expand, push the air out and (in theory) fill the top tank, but when it cools down again it will draw air back in through the little jiggly valve on the bottom of the radiator cap.

 

A recovery system basically works the same way except it expels coolant as it warms up and draws coolant back in as it cools.

 

Recovery systems are mainly needed on engines prone to trapping air pockets somewhere in the system, typically in modern cars where the radiator is often below the highest point of the engine.



#6 kavesh

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Posted 02 March 2023 - 01:17 AM

Do you want shiny or boring standard plastic?

 

attachicon.gif 9BE7A37F-F43F-46E5-99C1-5B860362D50C.jpeg

 

Shiny is best.

Yes I also like shiny, buts sometimes the boring plastic, gives you a good indication of fluid levels at a glance and how clean the coolant is.



#7 kavesh

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Posted 02 March 2023 - 01:21 AM

I can understand why that water level seems weird, but If you don’t have a problem with running temperatures, why are you worrying?
Maybe you could check out a system from the mid 80’s with a coolant tank setup.
I have a 1985 commodore with a plastic coolant reservoir on the upper inner guard/ shock tower area
higher than the radiator cap and overflow outlet
Probably a common setup for that time period, Just the next factory development phase from yours.
South African cars must have followed suit in that era with similar setups,
perhaps you could find one over there you could duplicate,and acheive
the coolant level you want to see?
Check with a radiator system guy first, there’s more to this than meets the eye
To quote the yanks, (but probably the wisest thing they’ve ever said)
If it ain’t broke, don’t fix it

Like I said no temp issues at all, but with our summers getting hotter that extra 500ml to a litre may just help a little more to maintain good temp.

 

I have been looking at what the guys here are doing and most have aluminum radiators now with no filler cap, so they have pressured expansion bottles. Not what I need. I just need an overflow system. 



#8 kavesh

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Posted 02 March 2023 - 01:25 AM

If you're doing some weekend racing it may be a requirement to capture overflow.

 

Also difficult to get a non-recovery cap so doesn't hurt to use it. Doesn't have to be higher than the radiator cap (the tube at the bottom of the tank rarely is) but shouldn't be too low or the coolant may not recover properly.

 

I had a factory plastic tank until recently but they're marginal in size for a bigger radiator so made up a slightly bigger one.

20230107_152921.jpg

Lol....no racer here, more like driving Miss Daisey. 

Just a weekend cruiser really. 



#9 kavesh

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Posted 02 March 2023 - 01:28 AM

So guys in terms of capacity of these overflow tanks, what size does it need to be? Is there a relationship between coolant capacity and overflow tank?

 

The pretty shiny ones are only 800ml which seems too small in my mind.

 

The plastic ones appear larger although I am not sure of their size as yet. Need to take a closer look.



#10 Bigfella237

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Posted 02 March 2023 - 08:26 AM

There's a simple way to tell what you need...

 

When the engine is cold, use a measuring cup to fill the space in the radiator with your preferred water, and whatever it took should be the difference between the "COLD" and "HOT" markings on the overflow tank.

 

Thinking of most generic overflow bottles I'd guess the total capacity should be maybe double whatever your measurement was below the "COLD" line, plus your measurement again, plus that much again for expansion.

 

So I'd guess any tank you buy would need to be a minimum of four times whatever you measured to fill the radiator?

 

EDIT: 76's alloy tank is nice and all that, but there doesn't appear to be any way to check the coolant level without constantly removing the cap and peering inside?

 

It needs something like this attached:

 

sight-glass.jpg

 

I found the above using goggle here: https://au.rs-online...vel-indicators/


Edited by Bigfella237, 02 March 2023 - 08:34 AM.


#11 76lxhatch

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Posted 02 March 2023 - 12:56 PM

Its stainless, and no you can't check it without removing the cap but the same could be said of the radiator.

 

I've seen people make neat level indicators with right angle fittings and clear tubing. I made it big enough that you don't need to constantly check it, just occasionally pop the cap and make sure there is a bit in the bottom when cold (and the radiator is full).



#12 Uncle Chop Chop

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Posted 03 March 2023 - 06:41 PM

If it ain't broke, don't fix it. Having said that, it's cheap insurance.



#13 jpxu1

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Posted 03 March 2023 - 09:19 PM

If it ain't broke, don't fix it. Having said that, it's cheap insurance.

 

Yes, it sounds like a good theory, but I believe it's always better to remedy before "it's broke"!



#14 Uncle Chop Chop

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Posted 05 March 2023 - 06:39 PM

Which is why I said it's cheap insurance.






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