Coolant level...wheres it going?

[ScottyP45]

I topped up the expansion tank just 3 weeks ago or less cos it was below max, then this morning the car started moaning about coolant level itself this time, when I checked it was below min!!!

I filled it up but is this normal on the 18T? Anyone else get this too before I start looking for leaks....?


My B5 and Golf GTi never ever needed water put in them, and the Golf was 16 years old. There was a wee puddle under the front of the car this morning but its cool and dewy so I thought it was just run-off from the bonnet and bumper.

It never overheats, no signs of any problem except disappearing water. Now I know all the usual reasons for this in general with cars, but im wondering if we all have this as normal?

 

[Woorlord]

Many times I've had problems with 2 previous VW Passat's which the B6 is based on. One was a 2.0L petrol the second 1.9TDI(130). On the petrol the leak must have been small cause I would top it up now and then. But the 1.9TDI - many occasions I would fill it up then 3~7 days later get a large flashing red "S T O P" on the dashboard - check coolant. It had all gone from the header tank. Garage did replace the radiator after the 3rd or 4th time as it was found to be leaking.
This is not an uncommon fault I believe on these models.

I too got very small puddles under the front on occasions - could not see anything obvious cause of the under tray covering the engine bottom.

It was a Company lease car so no personal expense - just inconvenience.
(Made me carry several litres of water around in the boot as a precaution - in a container!!)

 

[1wheelonly]

evil
topped mine up twice in a year, looks like youve got a leak mate,start by looking at the expantion bottle cap mate, im sure i read somewhere that the seal sometimes goes on them and the hot water ivaporates or something down them lines
worth a look mate

 

[Macduff]

If you've got a puddle at the front then probably a leak from the radiator (stone damage?) or maybe a hose.

I've never had to top up any vehicle I've owned so I would say it's not normal.

 

[ScottyP45]

Thanks guys, I wondered if this was common.

The car doesnt always leave a puddle, just sometimes so that might point rightly to the expansion tank cap seal as you say (1wheel cheers mate) - which I wouldn't have immediately considered. I will keep an eye on it and get it pressure tested at Falkland Performance Centre in Glenrothes, I've had all good experiences with them when a repair was beyond doing at the doorstep.

That should show where its going, and I'll check the rubber seal on the exp tank lid because it would indeed evaporate water if it leaks under pressure and that would leave little or no trace except for the disappearing water level.

Funny like macduff says, I never had to top up a car unless there was a problem with the coolant system but usually it showed up as overheating or an obvious leak, but this runs normally, just eats water! Maybe when I topped it up the other week the seal may have been dry and now twisting, shall check that.

Woorlord, thanks mate, any ideas what a radiator costs for one of these beasties before I start trawling round google sponsored ads lol

 

[HAWKEYE]

Funny Evil I've had the same problem over the past 5 weeks, never had it before then! I keep getting the coolant warning light coming up, and found water gone, sometimes light flashed after filling tank up. I did do a check for leaks and found nothing, even checking it everyday ( never seems to go then, watched pot and all that! ) now it seems to have stopped. Strange!!

 

[ScottyP45]

hmmmm - weird eh? I seem to remember my Alfa (53 plate) did this for a couple of weeks now I think of it, then stopped by itself.

Im thinking then that the dropping coolant is indeed caused by a leaking expansion tank cap seal such that the water is "steaming" away bit by bit when its up to temp, so the loss is gradual but steady. Today im going to have a good look at the cap seal since it needs topped up again (and you gradually lose all your anti-freeze doing this!)

One other thought...the other day when I stopped at the garage to check the level, and it was low, that although the cap seemed tight there was no real sound of pressure release when I unscrewed the cap, so maybe it was already equalised by the cap leaking off steam, but at the same time the temp never went up as the car warns you as soon as you go below the min mark.

For thos of you old enough to have driven 70's or 80's audi or golf, they actually were very hot running engines and a lot suffered head gasket failure due to the cooling system being quite poor and prone to leaks - including the rad caps, maybe its time to revisit the subject.

 

[1wheelonly]

where are you evil?
anyone close enough to you to swap caps for a bit, if anything it will either solve it or rule it out, cant imagine there expensive anyway mate.
ill get you a cap and you get my battery!!!!! lol
like you said a pressure test would be the best answer mate.
let us know how you get on, hope it is just the cap.

 

[ScottyP45]

im in north-east scotland mate, in the dogs-head - thats Fife (look at the shape of it, surrounded by water on 3 sides it looks like a scottish terriers head)

It seems to have stopped again since removing and re-fitting the cap the other day, i may try vaseline on the seal to make sure it is gas-tight.

 

[JamesS4cab]

I had the same problem with my S4 cab - took it to a specialist and he diagnosed that both auxillary rads were shot. They sit behind the headlights, and when he showed them to me when i collected the car, the end caps were just coming off. There was pink coolant everywhere down the sides of the rads.

Mine is 4 years old, and the fronts of the rads were perfect as they have so much protection from the headlights etc - the rads themselves arent that big.

Apparently its a common fault that the end caps aren't strong enough and the rads need replacing. I think all in inc fitting, it was circa £350 for two rads - same as i paid for one to replaced on my Boxster!!

 

[ScottyP45]

ok, the dropping water level is back just the same, but I noticed there is no rubber seal or o-ring on the cap! I would expect one, so maybe it dropped off when it was removed once, didnt notice but surely there cant be a vapour-tight seal with hard plastic against hard plastic, plus theres a groove that looks like its for a seal,

Can anyone look and see if they have a rubber seal around the cap??

 

[1wheelonly]

sorry for the bad pic but it was late and only had phone to hand,anyway hope this helps evil.
as you can see there is no seal round the cap but if you look where the end of my key is,in the middle section there is a rubber o-ring around the black centre piece,judging by how it sounded when i removed the cap,it must be like a vaccum,i think the centre with the o-ring is sucked into position and becomes sealed.
hope this helps a little mate.

 

[oneninet]

hi evil
dont really have any good as in not expensive idea as to where your coolant is going , but i tried my cap and it closes with a definite click rather than just tightening up. HTH
you have i presume checked your oil levels and noticed no rise ? no mayo on the oil filler cap hopefully , i too have the 1.8 T and give it about a half litre of coolant every 6 months

 

[ScottyP45]

thanks for the replies lads.

Mine doesnt seem to have any o-ring at all, and never gives a rush of pressure when released, even when the engine is hot, it sits just over 90 on the gauge and 50 when sitting still for any length of time, so I guess the cap is gassing out when the pressure rises allowing evaporation to occur and must be maintaining just enough pressure to keep the water from boiling.

Mine clicks but releases easily and screws down easily so im guessing its a bad seal. I notice they are only £4.70 from vag parts, but they dont list them as audi bits, either golf or unspecified....anyone know if thats the right one?

Might just try an o-ring from stores at work, at least for now till I know which cap I need to order, theres a good vw parts place in kirkcaldy - not far from where I live and they will order audi bits for me and look them up in etka too so you dont need the part number, good lads there, called Specialist Cars in Mitchelston Estate, Kirkcaldy, Fife if any scots lads on the east coast are looking for audi parts.

Got a new oil dipstick tube from there, as the old one was completely fecked and it was a pig to change, but necessary and looks good too. £2.50!

 

[1wheelonly]

if youve got no oring evil then i guess thats the cause.
let us know the results mate.