blakep82
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| posted on 22/6/10 at 02:32 PM |
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what sort of volume...
is everyones (custom) header tanks?
just been drawing mine up, appears to work out to a volume of 3.4 litres. seems a bit much lol
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Bluemoon
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| posted on 22/6/10 at 02:44 PM |
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Enough to allow for water expansion when hot (i.e. air space) mulitpled by 2 or 3 I would guess..
Dan
Quote "Water expands 4% in volume from 20 to 100C, so do you have 4% of the coolant volume as airspace in he header tank.. You should have more
room that this though, so say you need at least 8% or so air space, i.e 9ltr system would need at least 720ml of air space in the header, and would
pressurize the system to 15psi or so when hot (i.e. the air space is half the size (310ml) when hot due to the water expansion), I guess you might
want more airspace if you run a lower preasure cap?
I had the same problem, and the above appears to be my answerer.. I just removed some fluid to make a bigger air gap in the header tank (about
300ml).
I ideally need more air space, currently the header water level not much higher than the top of the engine, ideally I would have more head of water
(i.e. higher header tank).. Also the heater pipes and choke thermostat are higher so also have a bleed to get the air out... The other option is a
sealed system, with a two way pressure cap and expansion bottle.
I though I had a possible head gasket issue but this seems to be the explanation in my case.... If I over filled I would loose a lot of water from the
preasure cap..
Dan "
From an old post..
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blakep82
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| posted on 22/6/10 at 02:47 PM |
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interesting. never knew it was such a mathematical reason for sizes. now, if i was to just half fill it, thats fine isn't it? as long as its not
below the level of the cylinder head?
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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Bluemoon
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| posted on 22/6/10 at 02:55 PM |
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quote:
Originally posted by blakep82
interesting. never knew it was such a mathematical reason for sizes. now, if i was to just half fill it, thats fine isn't it? as long as its not
below the level of the cylinder head?
Well that was my take, seemed to be about correct.. As most cars have a similar volume of coolant I expect in most cases it "just works"
but as I found out that's not always the case. My cap still vents but only air, going back in after a run... It must vent on a run (else it
would not be able to suck air back in) but I can't hear it, and no water is lost..
I think your idea will work fine so long as it's big enough (i would be happy with 3ltrs)...
Dan
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blakep82
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| posted on 22/6/10 at 03:28 PM |
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i plan to make the cap just higher than the engine and radiator, so its well above the level of the cylinder head. i guess it will end up filled to
about 2 litres, with maybe 1 litre spare for air. i guess the size keeps weight low, and stops the risk of it floping about too much and breaking the
moutings
http://locostbuilders.co.uk/upload/6header.jpg
here's a link to a rather large photo of the kind if thing i've planned from the hole at the bottom (which will be used to bolt to a lower
wishbone bolt) to the top of the cap is 17 inches
[Edited on 22/6/10 by blakep82]
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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wilkingj
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| posted on 22/6/10 at 04:02 PM |
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I go along with this...
I always loose exactly the same amount of water, be it a short or long trip. Every time without fail.
So....
I have changed my pressure cap (Std metal Push n Twist type) for one off a series 3 Land Rover.
This has the normal rubber seal on the springy bit, AND a rubber seal inside the top of the cap which seals to the top lip of the filler neck.
Then you feed the overflow out to a bottle, and the tube Must reach the bottom of the bottle.
Thus the water expands, exits through the cap, and into the bottle.
Now when it cools, the additional seal in the top of the cap allows the water to be sucked back from the bottle into the header tank.
The key is to have the overflow pipe reach to the bottom of the bottle, so it can suck the water back up when it cools.
Land Rover did this for years, and it works well.
All I need to do now is to replace the coke bottle and cable ties with a decent ally or stainless bottle made for the job.
Another job now on the list!
1. The point of a journey is not to arrive.
2. Never take life seriously. Nobody gets out alive anyway.
Best Regards
Geoff
http://www.v8viento.co.uk
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