2 minutes ago, TMB said:

No O-ring.

 

Wow, missed that, seriously?

 

Buy a new cap, fixed. FFS.

I am mistaken - there is an O-ring around the centre inner part.

 

Edited 26 February, 20197 yr by TMB

35 minutes ago, TMB said:

No pressure when cold is good. 

Yay! 

 

So no alarm on the way home. If its all good by tomorrow afternoon then my thinking is its expansion tank, the reason being I keep parking it on the flat and I think it's leaking from the join between the two halves of the sphere, so.. If its okay tomorrow then tomorrow night I'll park it as I normally do, nose first down the drive on a downward facing slope, if it leaks and the alarm goes off again then presumably that proves its the tank seal? 

29 minutes ago, TMB said:

I am mistaken - there is an O-ring around the centre inner part.

 

 

Yes, that's where it is on every VAG vehicle since about 1976.

 

The black bit has a pressure relief spring and will allow coolant to spurt out of the flange on the blue part, hence the outside of the tank gets wet when it blows.

 

Not rocket science chaps.

Is the O-ring actually missing off your cap then Aaron?

19 minutes ago, AaronMountford1990 said:

Yay! 

 

So no alarm on the way home. If its all good by tomorrow afternoon then my thinking is its expansion tank, the reason being I keep parking it on the flat and I think it's leaking from the join between the two halves of the sphere, so.. If its okay tomorrow then tomorrow night I'll park it as I normally do, nose first down the drive on a downward facing slope, if it leaks and the alarm goes off again then presumably that proves its the tank seal? 

 

No, there is no join, the tank mould is in two halves so that 'joint' is the flash line from the moulding, tanks don't leak, you'd have to crack it with a big hammer for it to leak.

50 minutes ago, sepulchrave said:

 

No, there is no join, the tank mould is in two halves so that 'joint' is the flash line from the moulding, tanks don't leak, you'd have to crack it with a big hammer for it to leak.

That's not where I meant o ring wise, I thought there may be something on the outer race, I'll take a pic tomorrow. Good to know it shouldn't be the tank then unless it's cracked. 

Will update more tomorrow when it's light 

1 hour ago, AaronMountford1990 said:

That's not where I meant o ring wise, I thought there may be something on the outer race, I'll take a pic tomorrow. Good to know it shouldn't be the tank then unless it's cracked. 

Will update more tomorrow when it's light 

 

No need for a picture, the cap is designed to leak coolant from the outer 'race' as you call it, there is only supposed to be one o ring on the black centre piece which is also the pressure relief mechanism, nowhere else.

 

I will say this only once more, if your cooling system is over pressurised then the cap will blow coolant out while you drive.

If you have no residual pressure in the system when it's cold then you have a stuck thermostat or a blockage somewhere.

If you do have pressure when the engine is cold then its head gasket time.

16 minutes ago, sepulchrave said:

I will say this only once more,

 

Edited 26 February, 20197 yr by TMB

I'll never think of sep in the same way again.

^ Haha 

12 hours ago, sepulchrave said:

 

No need for a picture, the cap is designed to leak coolant from the outer 'race' as you call it, there is only supposed to be one o ring on the black centre piece which is also the pressure relief mechanism, nowhere else.

 

I will say this only once more, if your cooling system is over pressurised then the cap will blow coolant out while you drive.

If you have no residual pressure in the system when it's cold then you have a stuck thermostat or a blockage somewhere.

If you do have pressure when the engine is cold then its head gasket time.

Okay, gotcha - so the caps fine as is. 

 

Touch wood, no alarms again this morning, i'll check the level again this afternoon and if okay i'll park it on a slope tonight as that's been the only difference in terms of it leaking or not.

 

There was definitely no hissing when removing the cap when the engine was cold, and I've just replaced the thermostat housing, thermostat and O-ring, so it's not the stat right? Was a genuine part btw.

 

 

 

 

Did you try removing the cap again this morning before starting up?

11 minutes ago, Wino said:

Did you try removing the cap again this morning before starting up?

Nope, but i can tomorrow ! You thinking it could be pressurising over time when left? 

No, that's not possible.  I just want a few re-checks to help eliminate HG trouble.

9 minutes ago, AaronMountford1990 said:

Nope, but i can tomorrow ! You thinking it could be pressurising over time when left? 

I don't want to step on anybody's toes but just want to help clarify the guys points. Your losing coolant at a considerable rate which could spell head gasket failure, as they've told me in the past it is caused usually by the cylinder head bolts stretching over time and causing 'head lift' which allows coolant to pass the gasket into the cylinders and exhaust gases in the water jacket in the other direction. What they would probably want you to do and what I would strongly suggest testing is...

 

1. Driving it hard sometime today if your out and about, giving it as much boost as possible, revving to about 3,500rpm before changing up for a good test (I did that).

2. Allow it to cool over night with out starting it.

3.Open the header tank in the morning as quick as you can and see if you hear a 'hiss' similar to the vid in the link Il send in the next message.

 

If it does 'hiss' then it's extremely likely you have head gasket failure as I have had late last year. Hopefully not but could be.

 

 

https://m.youtube.com/watch?v=dExI-RMydpA

 

Have a listen to mine, and compare with yours in the mornings. Best of luck

11 hours ago, Wino said:

No, that's not possible.  I just want a few re-checks to help eliminate HG trouble.

Checked again this afternoon, quickly removed cap when cold, engine not running, no pressure. 

 

So based on what sep said I've a stuck flap or blockage, what now! 

 

Can a flap be picked up by doing a vcds sweep to open and close the flap? I've scanned for codes using an obd reader and there's nothing there. 

 

When I checked it this afternoon it'd used a bit of coolant again, so I topped up again. 

By flap I suppose you must mean thermostat? I can't spot a mention of a flap in his  'I shall say this only once more' post.

You've just changed that haven't you?  Does the temperature gauge get up to 90 and no higher?

16 hours ago, Wino said:

By flap I suppose you must mean thermostat? I can't spot a mention of a flap in his  'I shall say this only once more' post.

You've just changed that haven't you?  Does the temperature gauge get up to 90 and no higher?

Thermostat's been changed yeah along with it's housing and o ring - it was never really faulty it was just a suspected leak area so I did that first, the temperature gets to 90 and doesn't go any higher no, i did notice when i replaced it all, it says to wait for the fans to kick in and out a few times - I've never heard the rad fans kick in, i assumed because the ambient temperature wasn't high enough to heat soak.

 

I said flap because I'd been talking about the heater position flap in the same day haha, my bad. the heaters tend to have two functions, hot, cold, nothing inbetween, all fan speeds work fine. 

Oh well, all a complete mystery, probably magnets or aliens or a deep-state conspiracy.

17 hours ago, sepulchrave said:

Oh well, all a complete mystery, probably magnets or aliens or a deep-state conspiracy.

Uhm, nope! 

 

I'm definitely leaking from somewhere or somethings blowing what it thinks is excess coolant out because some part of the system is blocked - I've used nearly a litre of coolant in just over a week.

 

Is it worth draining the coolant out again then removing the lower rad hose and putting a hose into the expansion tank to see if there's some deposit in there somewhere that will run out?

So. Cleaned off the expansion tank and will see if it spits again, as it may be doing so. 

 

What's on the rhs of the engine (as you look from the front of the car) that could be a point of leaking? If you put your hand there you can feel fluid and its in the right location to be dropping down the box and onto the floor!

Why not pop a new expansion tank on? They're cheap and then you can completely rule that out.

13 hours ago, TMB said:

Why not pop a new expansion tank on? They're cheap and then you can completely rule that out.

I was thinking of doing that but we've found a wet area. If you stand facing the car, On the right hand side between the block and air box there's fluid there were unsure if it's a pipe or something as I can't find my Haynes to check what's there and the workshop manuals on Facebook don't open properly on my phone all the images are missing