Losing coolant through expansion bottle vent.

UVK

UVK

Member
Hi all,

This has been an on going problem that has caused major frustrations in the heat wave we’ve been experiencing.
In a nutshell, my coolant system is is really over pressurised... to the point where I’m losing coolant which is spraying out through the little square vents on the side of the bottle.
There seems to be no other visible leakages anywhere. I know it’s coming from these little vents as there is tell tale water mark dribble from this area which then pools around the lip where the 2 halves of the bottle are fused together.
I replaced the cap originally thinking it was faulty before I witnessed these exit dribble marks.
The coolant is lost a lot quicker when at higher speeds and revs. The car can idle all night on the drive with the cap off and not lose a drop!
I poured gasket fix into the system after draining on the advice that it the head or gasket leaking combustion gases into the coolant system but it doesn’t seem to have helped? Also, would I witness bubbling in the expansion bottle with the lid off if that was the case??
I would LOVE to get this resolved without aimlessly replacing parts in the hope of stumbling on the problem. The old girl has had a lot of parts replaced over the last 6 months... most recently the alternator clutch pulley that decided to abandon ship mid journey! ! ! The coolant problem is about the only outstanding task to resolve on a pretty substantial to do list. Any help, previous experiences or guidance would be fantastic as I’m all out of ideas and the OH is pressuring to get rid of the car..... not on my watch love!!! Let’s prove her wrong and get the little tub running sweet again! ?
 
UVK said:
Hi all,

This has been an on going problem that has caused major frustrations in the heat wave we’ve been experiencing.
In a nutshell, my coolant system is is really over pressurised... to the point where I’m losing coolant which is spraying out through the little square vents on the side of the bottle.
There seems to be no other visible leakages anywhere. I know it’s coming from these little vents as there is tell tale water mark dribble from this area which then pools around the lip where the 2 halves of the bottle are fused together.
I replaced the cap originally thinking it was faulty before I witnessed these exit dribble marks.
The coolant is lost a lot quicker when at higher speeds and revs. The car can idle all night on the drive with the cap off and not lose a drop!
I poured gasket fix into the system after draining on the advice that it the head or gasket leaking combustion gases into the coolant system but it doesn’t seem to have helped? Also, would I witness bubbling in the expansion bottle with the lid off if that was the case??
I would LOVE to get this resolved without aimlessly replacing parts in the hope of stumbling on the problem. The old girl has had a lot of parts replaced over the last 6 months... most recently the alternator clutch pulley that decided to abandon ship mid journey! ! ! The coolant problem is about the only outstanding task to resolve on a pretty substantial to do list. Any help, previous experiences or guidance would be fantastic as I’m all out of ideas and the OH is pressuring to get rid of the car..... not on my watch love!!! Let’s prove her wrong and get the lit'mtle tub running sweet again! ?
Click to expand...

I'm afraid that the only way the cooling system could become pressurised like you describe is as rthe result of a faulty head gasket.
 
shkcjn said:
I'm afraid that the only way the cooling system could become pressurised like you describe is as rthe result of a faulty head gasket.
Click to expand...
Mine does this too and did have a split in the head gasket. One new head gasket later and it still does it.

Compression tests are normal. I have had some success with ptfe tape on the expansion tank lid. I also have a split in the engine breather hose apparently which won't help so I'm getting that fixed next.
It's a pain (mine is a 1.6 fsi)
 
Just had this problem with my Fsi.
Head gasket is absolutely fine
The pressure has slit 3 separate small hoses over last couple of months and have had new header tank and cap
Then had a garage flush through coolant system a couple of times they then refilled system under pressure with new anti freeze and has been a lot better for last couple of weeks
I am going to try water less coolant when I am sure that I have no leaks as that creates no pressure.
 
If the coolant has not been changed as per Audi guidelines then there is a good chance there is unwanted residue and contaminates in your cooling system. As terrywindy1 said. Is your coolant a nice pink colour or is it brown. If brown then wrong coolant has been used and you are damaging your engine. It is eating itself from the inside. Drain all coolant out of system from lower radiator hose and by removing one of the water pipes from the oil cooler block just below the oil filter and dispose of the used coolant responsibly.Try to get as much out as possible by blowing air into the system. I took the small return hose off the top of the expansion tank and connected another piece of clean hose onto the tank and blew until no more came out of the other disconnected hoses. I would also change the thermostat now as it is cheap and you have already emptied the coolant out. Get your garden hose - hopefully no hose pipe ban- wrap some plastic around the end to make it a better fit in the radiator hose and turn the tap on. Let it flush for a reasonable amount of time until the water looks clear. Turn off tap and drain out all water and blow. If lots more sludge comes out, it probably will, connect hose up again and flush out, vary the water pressure a bit but not enough to blow the hose out the radiator hose, drain blow check and repeat again if needed. After you think you have all debris out blow out system. Reconnect all hoses and slowly fill system with G12 or its later versions. DO NOT USE ANY OTHER TYPES OF COOLANT. With the expansion tank cover off start the engine and bring it up to normal operating temp 90 Degrees, occasionally revving to 2000rpm, this should burp the system clear of air locks. Switch off, let it completely cool and check fluid level, topping up if needed. Fit cap, start engine , check for leaks and take for a 15 minute drive. When you get back with engine running check carefully for leaks, it is possible some remaining trapped air has come out of the tank overflow holes. Switch off let cool and check level again. If after this it is still over pressurising then it probably is head gasket.
 
Just to say a VW/Audi specialist garage in Bristol changed me £98 for coolant change with G13 and 2 lots of rad flush
 
Last edited:
I agree with depronman, that on the TDi engine, it has all the symptoms of a failing head gasket. Combustion gases leak past the head gasket 'fire ring' and pressurise the cooling system.

Cheers Spike
 
Thanks everyone for taking the time to reply. The system was drained and flushed prior to adding gasket fix liquid to the system, so the coolant is fresh and pink(G12).
I guess it is probably time to source a donor recon engine as I feel it wouldn’t be worth the expense involved just to replace the head gasket on a 180k engine?
Has anyone had a reconditioned engine transplanted... if so, what was the figure involved for the job?
Getting rid of the car is not an option... I promised my daughter that she could have the car when she passes her test as she loves it as much as me! She’s only 12 at the moment so it’s important that I come up with a long term solution to keep our A2 on the road. ?
 
Is a head gasket change a big job DIY? I’ve only seen it done on a Honda del sol and it was pretty straight-forward. In fact the guy doing it deliberately sought cars with blown head gaskets as it was an easy fix. Is that maybe an option before an engine transplant - worst case you need an engine swap afterwards anyway. I guess it depends if you need to keep it running now.


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head gasket is a simple (ish) job, and well within the spoke of a competent DIY'er
Recon engines will be difficult if not impossible to come by, so repairing you own is the way to go
I have an A2 tdi AMF engine with 288,000 miles on the clock and it still runs like a sewing machine, so don't let the 180K miles put you off a repair
 
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Ok, that’s very reassuring! Thanks. I just assumed that it would be a very labour intensive, costly job that would be beyond the realms of diy.
I think that is all the convincing I need to contemplate tackling the job. Are there any “how to” guides in here to use as reference?
Thanks very much for another much cheaper alternative! Your personal experience with a high miler running so well gives me lots of hope that there’s plenty of life left in my car. ?
 
UVK said:
Ok, that’s very reassuring! Thanks. I just assumed that it would be a very labour intensive, costly job that would be beyond the realms of diy.
I think that is all the convincing I need to contemplate tackling the job. Are there any “how to” guides in here to use as reference?
Thanks very much for another much cheaper alternative! Your personal experience with a high miler running so well gives me lots of hope that there’s plenty of life left in my car. ?
Click to expand...

If you don't fancy DIY - then if the car could be nursed over to WOM automotive, ask them for a quote. They do lots of work on A2s and come highly recommended from many club members.

http://womautomotive.co.uk/contact-us/

Cheers Spike
 
Mine too seems to be collecting coolant on the lip of the expansion tank, the headgasket was replaced before I got the car. Think maybe it's just a bit too full! (fingers crossed)
 
allypug said:
Mine too seems to be collecting coolant on the lip of the expansion tank, the headgasket was replaced before I got the car. Think maybe it's just a bit too full! (fingers crossed)
Click to expand...

That may well just be a slight weep from the seal at the centre of the expansion bottle. A change of bottle could do it.
 
Hi,
I thought it would be common courtesy to just chime in with an update on things as i hate reading through threads that just abruptly end without resolution.
Long story short, i tackled the job of replacing the head gasket myself. It was no easy task and not something i would like to think i had to do again, BUT, it worked! No more pressure or coolant loss!
While i was pulling the engine apart, i replaced the timing belt, water pump, tensioner, head bolts, cam cover (existing one had the corners over the cam shaft damaged and bodged up with silicone which werent visible when the engine was complete - some questionable work in a previous life?), and cam cover seal. I also replaced the thermostat and expansion bottle cap.
This is just a thank you to all that contributed to this thread and my plea for help and advice in my hour of need. This site has helped me tackle problems with the A2 that i would'nt contemplate doing otherwise. The lack of any "haynes" type manuals to refer to just adds to the mystique of this quirky, and at times, fickle beast.
Im smiling again now shes back on the road! Cheers!
 
You will soon be joining the 200k club ,
Well done In your efforts to overcome the leak.

Keith.
 
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