Radiator Overflow Is Filling But Not Emptying...

[arrydjay]

So lately I have noticed that my car has been using a bit of coolant.

Every couple of times I use it I just throw a bit of water in the radiator.

Today I decided to find out wtf is going on and I think I have figured it out.

My overflow bottle is hidden behind a custom panel I had made up so I havnt been able to check it.

Today I removed the panel and had a look and the overflow was full to the top with green coolant (a lot greener than the coolant in the radiator as I have been watering that down).

Its like when it gets hot it can overflow into the bottle but it cant get back...

I took the line off and blew through it and it isnt blocked or anything....

Any ideas?

[NYTSKY]

Small leak in headgasket which is pressurising the cooling system?

Im having this issue at the moment when I give the car a hiding.

[Frosty]

yeah cooling system is pressurising by the sounds of it! could be headgasket

have you bled it to see if there are any air bubbles in the system?

install a coolant swirl pot?

[scotty nm35]

Needs new head gasket and ARP bolts.

Smell the bubbles in the radiator, if they smell like petrol you are ripping the head off.

[jeffworld2]

can just be a crap seal on the radiator cap, not the centre spring but the top of the neck to the cap. I had this on mine, with a munted neck the cap was still holding pressure but it was easier to suck air back into the neck than to bring water back through. Bit of silastic and all was nice again.

[Frosty]

Needs new head gasket and ARP bolts.

Smell the bubbles in the radiator, if they smell like petrol you are ripping the head off.

yep agree

can just be a crap seal on the radiator cap, not the centre spring but the top of the neck to the cap. I had this on mine, with a munted neck the cap was still holding pressure but it was easier to suck air back into the neck than to bring water back through. Bit of silastic and all was nice again.

and this 2

start of small and work your way up! will be a process of illimination

[WMDC35]

def check the cap first

[MagicMikeZ32]

can just be a crap seal on the radiator cap, not the centre spring but the top of the neck to the cap. I had this on mine, with a munted neck the cap was still holding pressure but it was easier to suck air back into the neck than to bring water back through. Bit of silastic and all was nice again.

Agree with this.

Coolant heats up, takes easiest path into overflow.

Cools back down, leak somewhere lets air get sucked in to fill the gaps as that is easier than sucking the coolant back up from the overflow.

[HR32GTS 4DOOR]

Had this problem on my old engine. Turned out the head gasket had a tiny leak, If I wasn't paranoid about my car I wouldn't have noticed. Not too hard a job to replace.

Does the coolant system stay pressurised after the car is left over night? and does the top hose feel rock hard when warm?

[StevenCJR31]

radiator cap is f*kd or its the wrong one

[The Bogan]

Correct cap is 1.1 bar I believe.

[DVS JEZ]

.9 stock ?

[The Bogan]

.9 stock ?

I stand corrected, bloody REPCO will say anything to sell something.

[DVS JEZ]

Haha. I May be wrong. I always prefer .9.

It takes a very strong cooling system (ie not an old engine with 20yr old rubber hoses under the plenum) to handle 1.3bar pressure

[arrydjay]

well i was running a 1.3 bar cap... swapped it today to a 0.9 bar one.

I also bought one of those chemical combustion leak tester thingos but it came up all clear...lll see how it goes with the new cap.

[260tech]

Agree with this.

Coolant heats up, takes easiest path into overflow.

Cools back down, leak somewhere lets air get sucked in to fill the gaps as that is easier than sucking the coolant back up from the overflow.

^^ What he says is as good a place as any to start. Renew overflow hose (if you haven't already) from radiator to o/flow bottle & see how you go.

Cheers GW

[blah_blah]

Dang! Same thing happens to me.

Overfill bottle fill but radiator keeps on emptying. Think I too have a leaking head gasket from boiling the car last year.

Any consequences of having a leaking head gasket? I might just leave it and keep filling the radiator....no monies

[Manuel Kasko]

If the leak turns into a big one it could take your engine with it I guess?

Don't bandaid something like that and just spent the monies now to fix it before it turns into a warped head or worse

[scotty nm35]

Dang! Same thing happens to me.

Overfill bottle fill but radiator keeps on emptying. Think I too have a leaking head gasket from boiling the car last year.

Any consequences of having a leaking head gasket? I might just leave it and keep filling the radiator....no monies

I drove my VQ for a year like that, without realising it was the head gasket. It let go in a big way on the dyno during a tune.

Get a carbon test done on the coolant, it should show up any combustion bubbles making their way into the cooling system.

[arrydjay]

yeah I suspected my head gasket, but the combustion gas test came up all clear.... my mates S14 has been running like shit and we couldnt figure it out so I did the test on his and the dye changed colour straight away which means he has headgasket issues.

Its an awesome bit of kit... I got mine from repco for $130, just ring and make sure they have got one first as lots of places were out of stock when I was looking for one.

Here is how it works for anyone who doesnt know....

Edited December 1, 2012 by arrydjay