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Discussion Starter #1
I was just wondering whats going with my overflow bottle cap.

Ive been losing waterbut cant find any leaks, oil cap isnt milky.

Ill need to fill up the radiator every fortnight with about 1.5L of water.

I looked at the overflow bottle cap and am not sure if its working right.

When I blow into the inlet from the radiator into the bottle theres no resistance, it will fill up the bottle.

When I blow from the bottom of the cap, from the bottom of the bottle back into the radiator its fine.

When I blow BACK from the windshield end of the cap ( the section that spits out coolant into the engine bay ) its completely blocked. No matter which of the other end I block off ( radiator or back into bottle ).

Is this the way its supposed to work? does it need more PSI that I can blow into it to open some kind of valve?

If it was truely seized or blocked that would make it very difficult for the radiator to suck the water back if its sucking it from within a vacuum?

Would anyone be able to confirm if all 3 inlets/outlets should be free blowing?
 

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If you blow from the short end hose, that dumps into engine bay, there shouldn't be any resistance. It should just vent to the underside of the cap.
As far as loosing coolant, is your overflow bottle full? Like chockas?
When you fill the radiator do you fill it completely up the neck? Sometimes they need to find there own level, that may be an inch or so under where the neck meets the radiator proper, if you get my drift.
So you may be topping it up over where its natural level is and then its pushing it out into the over flow filling it then dumping it.
 

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nissan
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The hose is probably blocked with junk try blowing it out with air. But if it is blocked there should have been some sort of repercussion because the system is now sealed and can't breath and the pressure will build so a hose or something would usually blow off you may have a water leak somewhere else by the sounds of it good luck hope it's not a pricy fix.
 

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Is it the standard bottle, or one from Ebay? I got one off Ebay, that didnt seal properly. Did the same thing. I put the old one back in.
Mark
 

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Is it the standard bottle, or one from Ebay? I got one off Ebay, that didnt seal properly. Did the same thing. I put the old one back in.
Mark
I got a $26 cheapo from a mob in W.A about 4 yrs ago and on their site I remember them saying they don't supply them with a cap because they had problems with it sealing they recommend using the original one which has worked fine on mine. By the way his story reads he may have more trouble than that.
 

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BORDERTREK 4X4 & FABRICATION
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Would anyone be able to confirm if all 3 inlets/outlets should be free blowing?
With the cap off and disconnect from the radiator - Yes
Sounds like the hole in the cap head from the breather side is blocked.
When you blow into the cap nipple on the breather side it should flow through the cap head and into the bottle.
When you blow into the cap nipple from the radiator side it should out flow through the hose going into the bottle or vice versa.
Have you tried the hoses alone for blockage.
If anything there is solidly blocked it could cause over pressurisation in the cooling system and cause a leak somewhere.
BTW if the cap nipples are connected the wrong way around it can flow straight out the overflow breather and wont be able to suck coolant back in to the radiator because it would be sucking air from the top of the bottle not the coolant sitting in it.
 

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Discussion Starter #7
Update:

Ordered a cheapy overflow from ebay.

Installed it and it fixed the entire issue.

On the original I blew into the short hose and it was blocked, blew on the hose that came from the raditator and it was free and also the hose that was in the bottle.

Got new bottle and cap and blew into the short hose and its free flowing!! that explains why water isnt going back into the radiator when cooled down.

Tested on the original cap again and this time it WASNT blocked *face palm* so it was an intermittent issue.

Anyways new bottle and cap proved to have worked as I lost some coolant replacing my lpg convertor and the missing coolant from the cooling system sucked the contents of my overflow literally dry.

Filled the over flow to the max mark and its been great ever since.
 
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