Still losing coolant!

amimmortal

amimmortal

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Morning all...

Since May this year, when my EGR valve imploded, I've been having a 'mare with coolant loss from my 2004 C5 Avant Final Edition 1.9 TDi multitronic.

See the following threads:

http://www.audi-sport.net/vb/a6-s6-allroad-forum-c5-chassis/158523-1-9-tdi-flatlining-limp-mode.html
http://www.audi-sport.net/vb/diesel-forum/170659-egr-cooler-gone.html
http://www.audi-sport.net/vb/diesel-forum/161246-major-issues-following-egr-failure.html

So far this year, I have had the following checked/ replaced/ repaired:

May/ June - EGR Valve failure

EGR Valve (this disintegrated, resulting in the screws and spindle ending up in one of the cylinders)
Cylinder Head Gasket/ Bolts (required after checking the cylinder/ piston for damage etc as a result of the EGR failure)
Timing Belt/ Water Pump etc (60,000 mile service, including brake fluid change, filters etc)
Oil Cooler (this failed shortly after the EGR, resulting in oil mixing with the water)

October - Coolant levels constantly dropping, about 1" per month from the expansion tank since June.

Coolant system pressure tested by VAG centre in Dunfermline. No external leaks found.
Heater Matrix checked for leaks, none found
Multitronic gearbox oil checked for glycol - negative result (rules out gearbox oil cooler)
New EGR cooler recommended by VAG - some white smoke on start up for a few minutes.
New EGR cooler fitted by Star Performance in Kirkcaldy (for obvious reasons!)

There is no water in the engine (no froth/ emulsified oil on the filler cap and oil levels within the normal range)

So, can anyone here make any suggestions as to where the coolant is going?

I've already spent the best part of £2500 getting all of this done (that includes the service and MOT, which it just passed) and I'm completely at a loss as to why the coolant is disappearing.

Please help if you can!

Cheers,

A.
 
You could have a cracked head, not common on the pd130 but common on a few other PD engines... If you cannot see any external leaks then the coolant is getting into the combustion chamber hence the slight smoke issue when starting...
 
adamss24 said:
You could have a cracked head, not common on the pd130 but common on a few other PD engines... If you cannot see any external leaks then the coolant is getting into the combustion chamber hence the slight smoke issue when starting...
Click to expand...

With all the time spent investigating the leak, I'd have hoped something like this would have already been ruled out?

How would you test for a cracked head? It's worth noting that there were no leaks whatsoever prior to the EGR valve failure. With this in mind, how could the cylinder head be damaged over the course of the work carried out?

Also, if the cylinder head is cracked, would oil not have coolant in it?

Someone has recommended Radweld, but I'm not too keen...

Cheers,

A.
 
How long does it take for your temp gauge to get to 90. If it is taking longer than usual your temp sensor could be stuck giving a constant open/closed coolant circuit and the water is just getting boiled off.
 
It took 15 minutes to get to 90, sitting in rush hour stop-start traffic. I'm not sure if that's a long time or not to be honest.

Where would the water vapour/ steam be escaping from if the temp sensor is faulty? As an aside, when I started the car to go home from work this evening, the left hand side of the windscreen was steamed up from the bottom to about half way up. Would that be symptomatic of steam escaping and condensing on the windscreen?

Also, would this not show up as part of the coolant system pressure test?

Thanks,
A.
 
amimmortal said:
It took 15 minutes to get to 90, sitting in rush hour stop-start traffic. I'm not sure if that's a long time or not to be honest.

Where would the water vapour/ steam be escaping from if the temp sensor is faulty? As an aside, when I started the car to go home from work this evening, the left hand side of the windscreen was steamed up from the bottom to about half way up. Would that be symptomatic of steam escaping and condensing on the windscreen?

Also, would this not show up as part of the coolant system pressure test?

Thanks,
A.
Click to expand...
think he meant to refer to the thermostat being stuck as that's what controls the flow of coolant through the radiator.
Also, not sure if this helps but my 1.9 tdi takes the same time to warm up as yours (but I suspect the thermostat isn't seated
properly so I'll be sorting this soon).
 
Your inside windows misting mean the heater matrix is punctured or the car is overheating, for example the water does not circulate in the system and it boils. If the water circulates trough the system then the head being cracked would only show when driven hard- not enough heat put in the system to overheat the engine but enough vacuum to pull the coolant inside the pistons where it will be expelled trough the exhaust. Sadly any coolant check is irelevant on a diesel engine...
 
Hi there,

It was just a patch of condensation above the glove box on the inside of the windscreen. I gather that the matrix is situated in front of the driver footwell, so that sounds a bit odd.

There's also no dampness in the footwell carpet, that you'd expect with this.

I don't see any evidence of overheating - the temp gauge sits happily at 90F once it's up to running temp and stays there regardless, unless the sensor is broken?

The garage have advised me to top it up and keep an eye on it as it could just be as a result of the EGR cooler fitting. That remains to be seen however...

Also, can you just explain what you mean by the coolant check is irrelevant on a diesel engine? Do you mean the pressure test?

Thanks,

A.
 
The steaming up of your windscreen on the passenger side could be due to the pollen filter being/getting wet as it sits on that side behind the glovebox area.
Have you checked to see if your expansion tank is leaking or not?
I have heard that they go underneath so it's not as obvious.
HTH,
Ta,
Deano.
 
The reservoir seems to crack with age...
No leak at rest but you keep finding grey/while flakes round the hoses and engine bay.
P1040360.jpg


Also worth dropping the under tray to see if there is any deposits round the cambelt cover...

These are the sort of flakes to look for...

P1030518.jpg


I had leaks from the water pump and the reservoir...
 
That relay roller did not look too healthy ! Glad you caught it in time !
 
amimmortal said:
Hi there,

It was just a patch of condensation above the glove box on the inside of the windscreen. I gather that the matrix is situated in front of the driver footwell, so that sounds a bit odd.

There's also no dampness in the footwell carpet, that you'd expect with this.

I don't see any evidence of overheating - the temp gauge sits happily at 90F once it's up to running temp and stays there regardless, unless the sensor is broken?

The garage have advised me to top it up and keep an eye on it as it could just be as a result of the EGR cooler fitting. That remains to be seen however...

Also, can you just explain what you mean by the coolant check is irrelevant on a diesel engine? Do you mean the pressure test?

Thanks,

A.
Click to expand...
If you have to top up then the head is cracked or the head gasket is blown ! Not bad enough to mix oil with water or to pressurise. I had a passat once with exactly the same symptoms but the temp. would have climbed sharpish as soon as the car got driven over 100Mph !
 
deanosabby said:
The steaming up of your windscreen on the passenger side could be due to the pollen filter being/getting wet as it sits on that side behind the glovebox area.
Have you checked to see if your expansion tank is leaking or not?
I have heard that they go underneath so it's not as obvious.
HTH,
Ta,
Deano.
Click to expand...

Hi Deano,

The pollen filter was just replaced at the service - is this fitted from behind the glovebox, or is it fitted from the engine bay side?

I have had a saturated filter before when the scuttle drain was blocked and the scuttle filled up with water.

Cheers,

AndyC
 
adamss24 said:
If you have to top up then the head is cracked or the head gasket is blown ! Not bad enough to mix oil with water or to pressurise. I had a passat once with exactly the same symptoms but the temp. would have climbed sharpish as soon as the car got driven over 100Mph !
Click to expand...

The gasket and head bolts were replaced when the EGR valve imploded. If the head itself has gone, I'd be interested to know why, as this should be very rare, shouldn't it?

As it happens, Jim at Star Performance suggested that I top it up and then see what happens, as according to him the level can drop after the new EGR cooler is fitted.

There's no sign of any coolant stains anywhere in the engine bay, that I can see without the cover off. I would like to think that the VW garage and Star Performance would have noted this when they were working on the car, given that they were looking for signs of coolant leak.

No doubt we'll get to the bottom of it eventually...

A.
 
amimmortal said:
Hi Deano,

The pollen filter was just replaced at the service - is this fitted from behind the glovebox, or is it fitted from the engine bay side?

I have had a saturated filter before when the scuttle drain was blocked and the scuttle filled up with water.

Cheers,

AndyC
Click to expand...

Filter located on passenger side next to battery...

P1040032.jpg



Same when the drain holes block up (battery removed)

P1040570_zps4d4c11b5.jpg
 
Hi there,

I took off the scuttle cover and the engine cover to have a good look for signs of coolant. As you can see, the pollen filter is clean and dry:

DSC02834.jpg


This is the scene immediately below the coolant tank, and there are no tell tale residues suggesting that the tank is leaking:

DSC02836.jpg


This is a closer look below the tank:

DSC02840.jpg


This is even closer, and the only sign of any coolant residue that could find anyhere:

DSC02841.jpg


I had a look at all the rubber hoses coming and going from the coolant tank to check all the connectors and again couldn't find any leaks. Some of them felt a tad perished/ brittle, but other than that, nothing alarming.

Please take a look and let me know if I've missed anything, and keep the suggestions coming.

Cheers,

A.
 
I'm keen to go back to the possibility that the leak is coming from the heater matrix.

Despite the VW garage not finding any evidence of a leak, this doesn't mean that there isn't. Something I may not have been clear about is the smell that comes from the engine bay and into the cabin via the vents, which is very reminiscent of hot coolant.

Given the relatively low rate of loss, and the lack of evidence, could it be that the leak is so small as to be almost impossible to see?

Although I haven't done it yet, should I just go ahead and put some K-Seal into the coolant to see if that stops it? Presumably, if there is a leak in the heater matrix, this will plug it?

What are the downsides to using K-Seal?

Thanks,

A.
 
Bump - also, what is the coolant system volume in the 1.9 TDI? I need to know if I'm going to be using Radweld/ K-Seal to try and fix the leak.

Thanks!

A.
 
Not sure I should encourage such activity as in if someone had the head off its probably their bad?

Anyway around 6.5lt

The anyway is due to Audi having a process of premixing 10lt and pressure filling the system. Not the 'driveway ghetto' method of pour and bleed.
 
Right, I'll start with basics..

Coolant can either

Leak out externally, to the floor etc.
Leak into the oil galleries.
Leak into the bores.

That's it. There is no other magical place it goes.
It's either leaking out, being burnt, or mixing with oil.

Next. Any decent coolant will dry up and partially close a small leak. I'm not talking about cheap crap, the super long life stuff will literally crust up, and all but stop the leak. Would be chunks of it behind the cambelt cover for example if it was the water pump. To the extent it rarely hits the floor. You can pick lumps of it off.
Again, cheap coolant will leave dry residue stains, but generally leaks to the the floor.

Coolant systems are pressurised. Even with pure water, they won't boil at 100. With coolant, it's even higher.
If the thermostat is stuck, the car will overheat. It may take longer on diesel's, but with not external cooling. It will overheat.
The coolant is not boiling off, it's just getting hotter than the car likes.
Any steam can only vent through the pressure cap on either the radiator, or expansion tank. If it was venting through a leak, it wouldn't overheat in the same way, as it would dump it's coolant before it leaked steam.

Misted up windows do not mean a heater matrix fault. They can. But much more likely there is a faulty door seal, membrane, bonding or seal on glass etc.
Just because the carpet feels dry, doesn't meant the deadening under it is.
It's usually a foamy material, which acts like a sponge.
With out taking carpets out, it would never dry out fully, not any time soon anyway. Especially if the leak source hasn't been fixed.
I've been in the trade for 14 years, and I can count the matrix's I've changed on one hand.
I can't say the same for the amount of door seals, membranes, etc. Not even on all my fingers and toes would I come close!
 
Thanks Rom,

I think the misted up windows were/ are a red herring - I've had a flooded scuttle and a broken screenwash line in the rear footwell, so I've had my fill of saturated carpets over the years. The misted windows have only happened a couple of times in recent weeks and could simply be normal condensation, typical of the season.

Would coolant in the bores be burnt off? If so, would this suggest a cracked head or gasket? Also, is there a simple test to confirm this? Would coolant in the galleries be visible in the oil sump/ filler cap (as a frothy emulsion)? Coolant leaking externally would be visible as you described, and so far we haven't been able to find anything.

How do I test the thermostat (and where is it), and under what conditions would I expect to see steam venting from the expansion tank cap? Would there be any VAGCOM codes indicating any of these issues?

As an aside, the smell (which I am assuming is coolant) is ever present, even when starting from cold - and it is noticeable inside the cabin. Could this smell be coming from steam/ vapour escaping from the expansion tank cap? Having said that, the smell is stronger the further back and down behind the engine you go (hence the heater matrix being mentioned).

Either way, I just want to get to the bottom of this and diagnose the leak as easily (and cheaply) as possible.

Autotechnik Rosyth, who repaired the original EGR valve failure, and replaced the cylinder head in the process, are very reluctant to accept that the head or gasket are in any way at fault, and going by previous experience I'm also reluctant to take my car back to them.

Having read various testimonials (positive and negative) I'm beginning to think that some Radweld might not be a bad idea. With the relatively slow rate of coolant loss, any leak is probably very small, and would hopefully be fixed by the Radweld. If the coolant level continues to fall, then presumably this would point at the thermostat?

Bear in mind I took the car from Fife to Kent and back in September, so even averaging 75+mph for 400 miles each way, the coolant only dropped by about 5mm. If the cylinder head/ gasket were problematic, would the rate of loss not be faster?

I really appreciate the advice guys, and would be grateful if you could clarify these points, to the extent possible without seeing the car.

Thanks,

A.
 
Coolant into the bores, would indeed be burnt with the fuel mixture. If theres enough, it will present as smoke.

Coolant in the oil, doesnt always emulsify. It will also sit under the oil when stopped. So if you drained oil, coolant (if any in there) would come out first.

A thermostat is unlikely in my opinion. If its stuck open, the car would run colder, and take longer to get to normal running temp.
If its stuck closed, the car would overheat generally.
A thermostat controls flow into the radiator. So closed, means coolant doesnt flow into the rad, so wont be cooled. So the coolant woul donly circulate the engine, which is why it would overheat.
The 'test' is removing it, and placing in boiling water, to see if it opens. But for the cost of them, its rarely done.
Id think vcds will only show coolant temp, theres no way of it knowing the thermostat position.

If being burnt in the bores, you can sometimes sell a fuel / exhaust type smell if you remove the exspansion cap. If bad enough, the bottle will discolour.
Theres an easy test with the correct tool / kit. Which uses liquid, to basically sniff out exhaust gases from the coolant system.
It will change colour if present.

Hot coolant, on an exhaust etc usually smells a bit sickly sweet / bitter. Its distinctive.

It shouldnt really ever vent any steam. In normal use, it doesnt need to. If it is, somethings overheating. The pressure relief system in the cap will vent when needed.
But again, this is to stop it over pressurising, which it wont do under normal conditions.
 
Thanks Rom,

I've topped up the coolant with a 50/50 mix of G12++ and water.

I'm going to see if the levels settle down - Star Performance suggested this might happen following the EGR cooler replacement.

If they continue to drop, I'll try the radweld and see if that stems the leak.

Cheers,

A.
 
I used Radseal in my wifeS Bora when we got it 2 yrs ago and it stopped the the slight loss of coolant.My A4 came with a leak from a crack in the tank at the back which took a lot of finding
 
Hi all - quick update.

I decided to have the block test done to rule that out (because if it was the head gasket, then I'd be able to get it repaired under warranty). Fortunately (unfortunately, depending on how you look at it) there were no combustion gases coming back through the cooling system.

So, to recap:

- Pressure test found no external leaks.
- Head test found no internal leaks to the bores/ head.
- No evidence of coolant pooling under the car.
- No misting up of windows.
- No obvious sign of coolant getting into the footwells.
- Visual inspection of heater matrix (what they could see) indicated no leaks
- No problems with the thermostat.
- Negative glycol test in multitronic box.
- EGR cooler replaced October.
- Oil cooler replaced June.

And, despite all that, I'm still losing coolant.

Definitely going to try the k-seal tomorrow. This has really stumped me, and the guys that have looked at it.

If anyone has any other ideas, please let me know!

Cheers,

A.
 
And, finally...

The coolant leak has stopped. K-seal did the job no problem.

I think I'll get the coolant flushed now to clear out any remaining K-seal and get a nice, new, clean coolant reservoir fitted.

Hopefully this is the end of this sorry saga!

A.
 
K seal usually blocks a lot more than that, keep the water flowing trough the heater matrix...you don't want low heat in the cabin especially in winter !
 
What is this K seal that you talk about? Do you have any pictures of it?
 
adamss24 said:
K seal usually blocks a lot more than that, keep the water flowing trough the heater matrix...you don't want low heat in the cabin especially in winter !
Click to expand...

The leak was in the heater matrix, so short of an 8 hour labour job to replace that, k-seal was the next best option.

It's generally considered to be better than Radweld, and less prone to causing blockages in the system. As I said though, I'll be flushing the system now that the leak is plugged so as to mitigate any risk of k-seal gumming up the works in the future.

@myth - k-seal is a copper/ ceramic compound that mixes with your antifreeze. It acts as a "seek and seal" for coolant leaks to air (no good for leaks elsewhere in the system). In my case, leaks were ruled out everywhere but the heater matrix, so it seemed the natural choice to avoid the dashboard removal!

K-Seal - Kalimex

A.
 
Oh, I see. I thought it was a specific seal of the car :)
Here in Romania, it's common to use an aluminum powder (100% aluminum) to seal the leaks which stops even the largest of leaks! It only stops the leak once you don't change the antifreeze: if you flush the liquid, the powder comes off and the leak... is leaking again.
 
Thanks all...

As it happens, my journey with the A6 will be coming to an end in a few months :-( And I want to make sure it's passed on to the next owner in the best condition possible.

It'll be due an annual service in April anyway, so I'll get that done, and I'll get the multitronic serviced at 70k miles just to be on the safe side. The issue I had with the rear speakers (referred to in a different thread), according to the auto electrician I spoke to, is probably related to the heater matrix leak - so by all accounts I just need to take out the unit, check for damp and corrosion, clean the contacts and just generally make sure everything is dry.

I'm moving onto a company car in May, and since Audi just aren't making enough effort in the CO2 stakes, I'm having to switch brands. After much deliberation, and having tried just about every people carrier and large estate we can, we've decided to get a Volvo :-O

I'm Looking at a V70, R Design D4 (163 BHP) in Rebel Blue (not to everyone's taste, but it looks fantastic in the flesh, and should hopefully go some way to mitigating the dullness that's associated with Volvo ;-))

Pics here - what do you think?

Myydään Volvo V70 2013, Helsinki (FKU-708) - Autotalli.com

It will, apparently, give 62.8 MPG, with 119g/km CO2, and provide 163 BHP and 0-60 in 9 seconds.

Oh, and it's bright blue too. Did I mention that?

Anyway, feel free to let me know what you think!

Cheers,

A.
 
Bet you never see that mpg. :) nice looking cars though, we used to have a V50 at my old work and it was nice to drive.
 
Indeed - but even with a conservative estimate of 55mpg (which I got on the test drive around Sighthill, up the bypass and back again) I can look forward to saving about £30 per month in fuel, over four years, which isn't to shabby.

Did you get my message about having a look at the head unit and wiring? Do your radio keys work? Mine are useless...

A.
 
*******'s forgot about that.
I have a good set of keys that you can use, when do you want to get them?
Looking at what you said about the matrix leak causing the stereo issues it will be worth your while to remove the comfort unit and make sure it's all good and dry as this control's other things to.
Deano.
 
Last edited:
Ahh - the convenience module.

A few years ago I had a leak in the rear footwell (flooded plenum chamber combined with split screenwash hose) and the module got a little damp. It was dried up, cleaned up and then, for good measure, sealed up. I've not had any of the tell tale symptoms, and with the leak stemmed, any residual moisture should dry out over the summer.

Worth a look though, like you said.

Let me know when you're free and I'll nip over.

Cheers,

A.
 
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