Crazy coolant loss on 1.6 tdi (15)

[Breezy_Pete]

Hey Skoda guys,

I am from Bulgaria and I have the same problem with my Octavia Vrs 2.0 TDI.

Like Cozza. my car has the same problem, but is out of warranty now and its around 200k km.

Also the car is loosing coolant around 300ml for 300km.

4 times I was in our local Skoda BG and we replaced the following parts:

- Water pump

- EGR coolant

- Changed all the coolant liquid to check for air in the system

- Made a pressure test without effect and they told me that we can continue with the Head.

 

Because I am out of warranty and I wanted to double check with other service not in Skoda, I took the car to other service.

- They checked again for  but there is no indication of leaking on the first view and they replaced the tank cap, but didn't help.

- They made some kind of video look if they can see any of sign of internal leak, but didn't saw.

- Now they will make some test pressure of inter cooler and if the results are low they will replace it, if not, we are going to remove the Head to check it.

 

I will keep in touch for my problem. Hope will give you a hints about this nightmare.

BR,

Vlad

 

Do you also find release of pressure when you take the cap off the expansion tank when the engine is completely cold? 

[Gladnika]

Yes all the problems are the same like Cozza.

When the car is hot and open the hood, the level is under the min, after some time around 15 min I left her to came cold, and release the cap, the level of the liquid is getting little bit more than min mark.

At the morning when the car is cold, if I release the cap I can hear hass, but the level its still under min. So there is a pressure.

[cozza]

Since the last few posts a tech told me via pm on here that its normal to hiss as its a sealed system and that the combustions gasses would force the cap off and ooze out water

[Breezy_Pete]

Please ask that tech to PM me and explain where the additional gas comes from.

[fgaffney]

I had exactly the same with my A3 TDi... water was being lost, no drips on the ground, the water pump was dry, no signs of any anti-freeze crystalisation... basically everything you've experienced. I kept telling myself it wasn't the head as the car was well out of warranty and I was facing a considerable repair bill.

 

In the end it was a cracked head which had to be replaced. I did another 60,000 miles before it started losing water again, although it was on a much smaller scale. Needless to say I got rid of it and replaced it with my Octy.

[James@RRG_Skoda_Rochdale]

It was me who Cozza was messaging.

What I explained was that it can be completely normal for the system to retain some pressure even over a long period, over night for example. I then explained that excessive pressure would cause the pressure regulated cap to release said pressure which would manifest itself as visible vapour and or red coolant stains around the expansion tank.

The above post is a little vague given my responses and my pms may not have been fully understood.

[James@RRG_Skoda_Rochdale]

I had exactly the same with my A3 TDi... water was being lost, no drips on the ground, the water pump was dry, no signs of any anti-freeze crystalisation... basically everything you've experienced. I kept telling myself it wasn't the head as the car was well out of warranty and I was facing a considerable repair bill.

In the end it was a cracked head which had to be replaced. I did another 60,000 miles before it started losing water again, although it was on a much smaller scale. Needless to say I got rid of it and replaced it with my Octy.

2.0 PD?

[fgaffney]

2.0 PD?

 

Yes... common problem with the early engines I believe? Symptoms sound identical to the OP unfortunately.

[Breezy_Pete]

The way I see it, if you take off the expansion tank cap when the engine's cold, say to top up the coolant, then re-fit it, there's no pressure in the (now sealed) system.  Heat up the engine and let it cool to the same temperature as before, and there can't be any more pressure in the system than when you sealed it with the cap. Same volume of coolant, same amount of air. That's what I understand as normal. 

 

Only if some gas is being added to the system from somewhere, can the pressure be greater in there after a heat-up, cool-down cycle.

 

Where am I wrong?

[James@RRG_Skoda_Rochdale]

Yes... common problem with the early engines I believe? Symptoms sound identical to the OP unfortunately.

As muck. There were 3 revisions of the head:

A - all cracked

B - most cracked

C - not many cracked

The cracks formed in the inlet and or exhaust ports.

[James@RRG_Skoda_Rochdale]

The way I see it, if you take off the expansion tank cap when the engine's cold, say to top up the coolant, then re-fit it, there's no pressure in the (now sealed) system. Heat up the engine and let it cool to the same temperature as before, and there can't be any more pressure in the system than when you sealed it with the cap. Same volume of coolant, same amount of air. That's what I understand as normal.

Only if some gas is being added to the system from somewhere, can the pressure be greater in there after a heat-up, cool-down cycle.

Where am I wrong?

Water boils at a certain temp. The cooling system works above that temp so in order for it to function correctly the system is pressurised which means the water portion of the coolant doesn't boil at such a low temperature .

The normal "pressure" which forms in the cooling system is steam pressure formed by the boiling water. Because this pressure is within the tolerance of the expansion cap it doesn't force it to vent and retains the pressure.

Edited 12 July, 2016 by James@RRGRochdale

[James@RRG_Skoda_Rochdale]

It only vents when the pressure exceeds it's tolerance.

Combustion gas to coolant is a prime example of when it would occur and it leaves signs of the venting.

[cozza]

Ok heres sonething from today i checked it this morning the level was at the max ive only done 35 miles 9 runs its been sat stil for about 40 mins engine off i just started it and coolant low popped up.

So i looked at the botyle no sign of water maybe a smidgen at the bottom of the tank so ive undone it as im on runs i have to do and the water has come up to max.

My question now is would the gasses force the water to a lower level? And then possibly out of the car?

Also today has only been around town driving nothing with high load

[Breezy_Pete]

In my experience, if a car hasn't got a cooling system problem, if I take the cap off when the engine's stone cold, there's never a hiss.

When I've had a car that has had a HG leak (3 times; 2 diff cars), there's been pressure in the bottle after an overnight sit.

In none of those cases was it bad enough that the car ran differently, or vented out of the tank (that I noticed), but following gasket replacement it went back to no retained pressure.

 

I know that the system does pressurise as it heats up, but by the same token, it depressurises by exactly the same amount as it cools down.

[cozza]

I just read your pressure explination after my post too.. i did a run come bk to loads of replys

Theres no marks on the cap or steam venting

[SuperbTWM]

The way I see it, if you take off the expansion tank cap when the engine's cold, say to top up the coolant, then re-fit it, there's no pressure in the (now sealed) system.  Heat up the engine and let it cool to the same temperature as before, and there can't be any more pressure in the system than when you sealed it with the cap. Same volume of coolant, same amount of air. That's what I understand as normal. 

 

Only if some gas is being added to the system from somewhere, can the pressure be greater in there after a heat-up, cool-down cycle.

 

Where am I wrong?

Can't fault your logic there. I've never had any hissing from an expansion tank when cold.

 

The thing is to be losing coolant the pressure in the coolant has to be greater than the pressure in the engine or wherever it is going. When you stop the car and the coolant system is still pressurised but the engine is not (unless it was leaking into a cylinder while it was on the compression stroke) you would think it would be leaking at this point, so you would think that there would be no chance of any pressure still in the expansion tank if you came to it the next morning as there would be a loss of volume of coolant in the system.

 

Just food for thought

Edited 12 July, 2016 by SuperbTWM

[Breezy_Pete]

It's good food for thought. 

I think my answer would have to be that if the leak path is only present above a certain engine temperature or power level (small  crack that expands when hot, or HG fire-ring to land gap); because of the very pulsy nature of pressures inside the head, two-way traffic may occur while that crack/gap is open. So coolant or vapourised coolant may squirt into combustion chamber or a port at times where the cooling system pressure is higher than the local pressure, and gases go the other way when they're at higher pressure than the cooling system. If the gap closes again before the pressures have a chance to equalise (by leakage whichever way the pressure gradient requires), the excess pressure will be trapped in the cooling system.

[James@RRG_Skoda_Rochdale]

Listen guys I'm not insinuating that excessive pressure in the expansion tank isn't an indication of a fault but I am saying that it's common for there to be pressure there even when the engine is cool and the vehicle having been stood for a time.

My crappy old bora can retain pressure for a few days after the engine has been turned off. The cooling system doesn't use a drop and that's been the case with a few cars I've owned.

Edited 12 July, 2016 by James@RRGRochdale

[cozza]

What do you think about todays issue james? How the tank went empty then when the cap turned it all went back to max? There was only 35 miles driven and 9 stops but it was sat there 40 mins or so with out the engine on so it should be cold or just warm before it went almost empty and the alarm came on

that seems like excess added pressure than a normal running system, i'm far from a mechanic or a tech knowledge wise,

it did it yesterday too so twice within maybe 100 miles or just over

[James@RRG_Skoda_Rochdale]

That can also be completely normal. When the system reverts back to atmospheric pressure the level wise rise where as when it's under pressure it will drop.

[cozza]

Its all a bit confusing and mega frustrating it has to be related to the problem or it would surely not do it, skoda coudln't have possibly designed it to do that (not from max anyway)

I had a 2009 Golf 2.0 TDI CR Sportline estate before this i never had any issues with the expansion tank i topped it up 2 times in 80,000 miles. All the other local taxis have never had a problem like this.

I do appreciate everyones help i'm just trying to absorb it all in and try to get some sort of a plan whilst i wait for skoda uk to contact me.

[Gladnika]

Hello guys, some update from me also...

My service checked yesterday the inter cooler, but its not from it.

Today will make some other pressure tests and if they cannot find anything will continue with removing the Cylinder Head..

[cozza]

I feel your pain Gladnika

I was called today by Skoda uk i now have a handler they have asked for a technical report from the dealer I expressed how the dealer who done the work has been great with me but were just struggling to fix it (a diff dealer sold me it)

So they are going to get there own skoda tech dept. to come up with a plan to fix it,

but unfortunatly I'm now tied up with work until the first week of Aug before i can allow them a third attempt on the car.

[Ootohere]

^^^ Best get that in writing.

 That spiel on the Skoda Technical Department is 'Communications Managers' rubbish often used.

The other one is 'We are contacting the factory'.

They know the engines, they know the issues, the engines are in many VW Group vehicles. 

No new issues, just the usual VW problem, keeping liquids in engines and out of passenger compartments ever since they stopped Air Cooled engines.

[James@RRG_Skoda_Rochdale]

I wouldn't hold your breath on the fix from the call centre, sorry I meant customer services.