Hi All,

 

New member and first post on here so please be kind, and this is a long one so be warned!

 

Recently become a happy owner of an Octavia 1.9tdi DSG 2007, until about ago when i started having problems with losing a large amount of coolant. 

 

When I say a large amount, In one week i have gone through  approx 5 litres of the stuff! 

 

Now, There are a few things that I have done/ checked/noticed but I wanted some further advice hoping you may have encountered this issue before. 

 

It first happened when I noticed a warning light come on, which is the flashing red thermostat light, so I pulled over, and suddenly found that the expansion tank was empty, so re filled and thought nothing of it. I do cover a lot of miles generally, and the next day, it happened again. Each time the bottle was completely empty (all be apart from probably 50 to 100ml at the bottom). There is no smoke at all and no white gunk under the filler cap, so I didn't know what to make of it. I looked and looked with the engine warm and cold, couldn't find much of anything but diagnosed the problem to be a leaking hose on the bottom of the expansion tank. 

 

So, trimmed the end of the hose off, got a new jubilee clip on the join and thought all is good. Re filled with more antifreeze and went on my way, only to find that It happened again. This time, I was just about to put the car onto a ramp for an engine oil change, and when I got the car off the ramps, there was a pool of antifreeze towards the rear of where the car was parked. Under the bonnet there was a hissing noise coming from the water bottle, like a pressure release sort of noise. You can visably see atifreeze collecting within the engine bay on the driver side of the engine bay. 

 

So, to add something else into the mix, last night I got home and the warning light came on again, and no coolant. So I filled it up and then went to bed. Returned this morning and the expansion bottle was full to the brim, and under quite a pressure with some seeping from a crack in the side of the bottle. Removed some fluid, and then lost all fluids again. This time, I noticed a wet patch in the bottom let hand side of the radiator. (might have been there before but has been raining etc so didn't notice).

 

If I pull off firmly or accelerate quickly, it appears to make it worse, and didn't lose a single drop on a 100 mile round trip where I took it very steady and sat at 60 all the way. 

 

My thoughts are that something is causing the pressure to build up when I accelerate firmly, causing the pressure to increase and thus losing the antifreeze at different weak spots. 

 

So, my question is, have any of you come across this before and would be able to give me some advice on what to look at next. I don't want to replace the cracked water bottle if it being cracked is stopping any form of further problems. I think the issue may be linked to a blocked radiator as the car was sat for a while, and perhaps a radiator flush and rad weld (or even a new one) might solve the problem for me. 

 

Any help of advice would be highly appreciated, 

thanks

Dan 

A small split in the expansion bottle has been reported before as the cause of coolant loss, fixed by replacing the bottle. However, the other common reported cause of coolant loss is a split head gasket, which over pressurises the coolant system causing the pressure cap to quickly release the gas and coolant. This may be the hissing noise you heard.

 

You need to replace the bottle anyway so I suggest doing that and as soon as possible afterwards, get a garage to check for head gasket leaks by chemical checks of dissolved combustion products in the coolant and/or a pressure test.

 

Your comments about hard acceleration suggests to me a head gasket failure.

 

 

 

Update - 

 

Been monitoring and trying different things and i have not isolated the fault to only when the car is under strain/high revs/accelerating firmly. The car doesn't seem to stay at 90 degrees, if it does reach that temperature it is normally when in traffic etc, and then drops back to 70 degrees for normal running. 

 

I have replaced the expansion tank which has made the system more stable, and there was obvious signs of deterioration on the old one, so it needed doing anyway. 

 

I havent had the head gasket checked, but have put some steel seal into the system and yet made it even more stable, so ruling out a head gasket leak. 

 

I have got white markings on most of the hoses on the off side of the engine bay and around the back of the engine but still not able to find a true cause as it looks as if its being sprayed out under pressure. 

 

I have a strong suspicion that the cause is a perishing hose or connection somewhere, and appears only on the side of the expansion tank. I have a new thermostat to put in anyway hoping that the car will then run at a more stable operating temperature and aiding further.

 

Does anyone have any suggestions on which hoses or joints are likely/common to fail as its driving me nuts...would it benefit from a simple pressure test? No leaks found overnight when the car is standing etc. 

 

Thanks 

It’ll be your head gasket, steal seal won’t completely fix the issue, been there still wearing the t-shirt, if your loosing such quantities of coolant and can’t see evidence of it around the block then it’s ingesting it, if your coolant system is over pressurising and you’ve bled the system properly it’s only real cause will be a failure between combustion chamber and water jacket, the fact you’ve got excessive pressure in the system shows the system is sealed everywhere else apart from the head gasket.

 

I've still got to remove the heads on my S4 to fix a broken head gasket, symptoms exactly the same, I even had a cracked coolant bottle 🤣 I used steal seal and it’s helped the issue meaning I have been able to go to shows, but when in boost it’ll still use coolant and pressurises the system.

 

i will say after a long while the steal seal got better, but I still have to keep a 5L bottle of coolant in the car.

 

 

for comparison the Octavia used water and it was the GSF thermostat housing leaking, signs of coolant loss down the block and on the under tray, you could smell the coolant plus no pressure in the system, new genuine stat cured the issue.

If you search the phrase "head lift" on here, you'll see it's quite a common problem on 1.9 tdi.

Thanks for the advice all, 

 

I have come to the conclusion that it probably is the head gasket -_- 

 

Spoke to a skoda specialist garage and they said that they can do a compression test once the head has been taken off to see if there are any issues further down such as cracked block ect. Is there any way of getting a definite answer to if its the head gasket gone or worse before I book the car in and start paying labour bills? 

 

Also - to add to the line of events - when the system appears to loose the coolant, obviously the water bottle becomes nearly empty. If the car is turned off for say 15 to 30 mins, and then slowly remove the expansion tank filler cap, you can hear the pressure releasing and approximatly 500ml or so re enters the tank. Is this also something that would be linked to this issue or is it likely that there are multiple problems? 

 

Thanks, 

Dan 

What, you mean just like this?

 

🤣 I will say the running cold issue is probably just a thermostat, my b5 runs fine temp wise, it doesn’t over heat or run cold.

 

i don’t think your engine suffers with the porous head issues, and I’d be surprised if you’ve cracked the block if your running standard power or even stage one map, I’d also like to think the escaping exhaust gas will mark the head gasket itself so you can see the failure, but I won’t know myself until I pull the heads off mine 🥴

Edited 11 February, 20206 yr by Vrsburnzy

Yes exactly like this