Coolant tank leaking. But what caused it?

[UniqueTimes]

Hi guys. Thought id share my discovery of a mysterious coolant leak. For about 4 months now i have been topping up my coolant every 300 to 400 miles and have been wondering what the hell is happening. I have had no oil and coolant mixing, no smoke occur, or any signs of coolant puddles or worse still the engine over heating, literally nothing guys. Today i got hold of a pressure test kit from friend who went ahead and tested my coolant system. The kits guage didnt even reach the usal expected pressure a car would achieve in operating condition. The pressure loss was instant and the source was quickly identified, it was the tank itself. It had perished and had around 20 pin sized holes in the plastic. If you see in my attach picture your notice a pinkish area on the left side of the tank and maybe some bubbles from the soapy water i used, across that pink band is where the holes are. Now luckily this was a gem of a result to find and not somethink more serious, and the problem is easily fix. But my question ultimately is why has this happened?

  There are no signs upon detective inspection as to whats caused it.  The perished area of the tank looks a cross between corrosive deterioration and melted plastic with some surface pitting . Now there was nothing in the surrounding area that showed any sign of being the cause to this, such as a melt wire or idk what.. This car is untouch and unmodified and in superb condition around the engine bay. Has anybody seen this before? Is it simply a worn out tank over time and the heat and pressures have taken its toll. But also as importantly what issues may this have caused over the past 4 months other than maybe 1ltr of coolant veung replaced... is it possible its caused further damage? Was my coolant working efficiently during this time concidering the pressure wouldnt have been able to increase as it was designed. Any advice, or first hand knowledge as to why this happened would be appriciated. Look forward to seeing what peeps have to say.

 

I own the petrol - Limited Edition Octavia VRS No.59 if that helps. 

 

Many thanks

[brad1.8T]

It almost looks like the corrugated plastic wiring cover has been abrading against it.

[Guest]

Curious that it appears there has been a corrosive spillage on the one side yet the cable tab remains untouched.  It looks like it had been sat on its side with something nasty inside.

 

It will be interesting to see what it looks like underneath and whether there is further damage below.

 

I'm sure many will be watching this mystery with interest.

[UniqueTimes]

Its possible "Brad1.8T" . Although the wiring with the corrugated cover you speak of is very tight with little slack and actually sits into a bracket attacted to the tank its self, i cant see it ever reaching the affected area to rub the surface of the tank so harshly. There also isnt any sign of rubbing on the corrugated wire cover either, at most just dented plastic. 

[UniqueTimes]

I to am curious "Micmac". I just today collected my new tank and shall be fitting it tomorrow. I will take more photos and post here once complete. Im also gonna cut the damage tank in half and see what the surface is like on the inside of the tank. I will report back. And yes it looks exactly like you discribed... (Sat on its side with a puddle mark of somethink corrosive which stained the plastic) 

[TheClient]

There are a number posts around where the tank becomes aged and fatigued. Mine has a few stress marks around it. Maybe the plastic just becomes brittle / susceptible to damage after a lot of heat cycles / certain amount of time. On mine you can see what looks like stress marks,.

 

See for example.  I probably should replace it Representatively next annual service.

 

 

 

Edited 11 December, 2017 by TheClient

[UniqueTimes]

Many thanks "TheClient" That has as good as answered my question.  I believe this is totally the case looking at thoses pic's on that link u sent.. A poor quality coolant tank and over time its weakened...simple as that. Weather a heavy foot has helped or not, the plastic used here is clearly not up to the job concidering the car/engine it is installed to. These tank really should last longer than the car itself. The pinkish discolouring on my tank is clearly coolant penertraing and staining the deteriorating plastic, which personally was giving the appearance of somethink corrosive eating the plastic. 

 

 

But thanks again. My mind is now at ease.

 

Just once last thing to everyone.... what could be affected by not having full pressure in the coolant system? may this have cause damage to anythink else? if anythink at all. Maybe a lack in performance (not that ive noticed it. Could it have stopped coolant circulating efficiently or anythink else? Any thoughts or knowledge would be appriciated.

 

[Breezy_Pete]

How much were you having to add at each top-up?

Unless you were having to add loads I doubt there would be any problems at all.

 

Edit, sorry, just re-read your opening post and you say 1 litre total. Nothing to worry about at all.

 

The pressure may well have been quite normal actually.  One of the effects of the pressurisation is to increase the boiling point of the coolant.  If the coolant was therefore tending to boil that would immediately up the pressure, so cancelling out any loss through leakage out of the bottle.

Edited 11 December, 2017 by Wino

[UniqueTimes]

Hi "Wino" . Thanks for the reply. Each time i notice the level had dropped, it had only ever dropped from the max to minimum mark maybe just under the minmum on loss of coolant. Its never become an empty tank, I seemed to catch it at the right time every time. So i guess about 125mil to 200mil each top up. If it had emptied i forsure would expect some over heating and bigger problems, especially if i didnt catch it in time. Seems my perticular nature has prevailed in this case. Im confident all is ok now. 

 

Guess we now know the extreme case of an old and deteriorated coolant tank and where its expect to occur on the tank it self.

 

Thanks guy's.

[mk2octavia]

I have a 2005 skoda octavia 2.0 tdi. Mine also has the deterioration at the same place, however, it is a lot smaller. I have noticed that it bubbles when the engine is warm.

I dont need to top up the coolant as often as you do

[UniqueTimes]

3 hours ago, mk2octavia said:

I have a 2005 skoda octavia 2.0 tdi. Mine also has the deterioration at the same place, however, it is a lot smaller. I have noticed that it bubbles when the engine is warm.

I dont need to top up the coolant as often as you do

Id be inclined to change it right away if you have notice holes in the same area as mine, if its just stretch-marks maybe just monitor it, but holes dunno bout that buddy. I notice mine yesterday, got part today and fitting it 2moro, but thats just me, better safe then maybe sorry i say. £20 fix or a new engine worse case if left n forgotten about.. If i wasnt so perticular with my car i may not have topped my coolant up in them 5 months and then bang goes my engine. Or if i keep topping it up knowing theres holes and one day im driving along the motorway at 70mph and that tank explodes because it structure is compromised and the pressure got to much, i mean why couldn't it do that its already failing right? I feel theres that chance. And a chance i wouldnt want to take. Treat your baby to a new tank .

 

And thanks again to everyone. I shall send pics 2moro with some close ups of the damage and how it looks from the inside also. But my ????'s are now confidently laid to rest. 

[mk2octavia]

20 hours ago, UniqueTimes said:

Id be inclined to change it right away if you have notice holes in the same area as mine, if its just stretch-marks maybe just monitor it, but holes dunno bout that buddy. I notice mine yesterday, got part today and fitting it 2moro, but thats just me, better safe then maybe sorry i say. £20 fix or a new engine worse case if left n forgotten about.. If i wasnt so perticular with my car i may not have topped my coolant up in them 5 months and then bang goes my engine. Or if i keep topping it up knowing theres holes and one day im driving along the motorway at 70mph and that tank explodes because it structure is compromised and the pressure got to much, i mean why couldn't it do that its already failing right? I feel theres that chance. And a chance i wouldnt want to take. Treat your baby to a new tank .

 

And thanks again to everyone. I shall send pics 2moro with some close ups of the damage and how it looks from the inside also. But my ????'s are now confidently laid to rest. 

 

Your right. I'm going to order a new tank for it tonight. 

[brad1.8T]

You fine Gents realise that the pressurisation of the cooling system raises the boiling point of the coolant?  If the expansion tank has a leak, it won't pressurise.

[Vrslad]

Having the same problem, car is booked in to have a replacement on Tuesday