The Student Room Group

Coolant keeps disappearing!?!?

Bit of a problem thats baffling me. Have a 2002 Skoda Octavia tdi and for some reason its using a lot of coolant (seem to be topping it up every time i drive it!!). I've looked under the oil cap and theres no white milky substance, i can't see any leaks underneath it when i move it and none of the hoses seem to be loose. Yet every time i've started it and warmed it up and set off the light comes on informing me of a lack of coolant (which lo and behold has seemigly vanished). Car spends most of the week parked up (with the odd trip to the shop) but is used at weekends to go between Devon and Kent and up to North Wales last weekend. After i top it up its fine for the entire journey (temperature guage in its normal place etc) yet whenever i park up and fire it up again as little as several hours later the light comes on and the coolant has vanished. Only think i can think of is the cap for the coolant tank in the engine is distorted slightly after i accidently shut the bonnet on it once, what do we think?
There may be a hairline crack in the coolant reservoir which opens when the engine's hot and allows evaporation? Try replacing the coolant reservoir (cheap and easy) and see if that solves it... If it doesn't at least you've narrowed it down!


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Reply 2
Definitely a leak somewhere in the system; where else would the liquid go (unless you're driving fast enough to open a wormhole to another dimension)?

Imho gravity would prevent the vast majority of the coolant leaving via the dodgy cap, so I doubt thats your issue. As the previous reply said, it is most likely the reservoir itself, or the hoses between it and the engine. Is there a visible leak on the floor when you pull up?
Reply 3
Original post by IWMTom
Definitely a leak somewhere in the system; where else would the liquid go (unless you're driving fast enough to open a wormhole to another dimension)?

Imho gravity would prevent the vast majority of the coolant leaving via the dodgy cap, so I doubt thats your issue. As the previous reply said, it is most likely the reservoir itself, or the hoses between it and the engine. Is there a visible leak on the floor when you pull up?


nah thats why i'm so *puzzled, theres no leakage from anywhere i can see when i pull up or when its left. Also (forgive me i'm not the smartest person in the world) by coolant reservoir you mean the bottle type i put it in? The problem was intermittent before but it occurs everytime i drive it now and i'll definetly look in to getting it replaced if thats the case. When i go home on holiday theres a Superb in a local scrapyard i'm planning on getting a new part off to see if that makes a difference
Reply 4
Original post by Y333EEE
nah thats why i'm so *puzzled, theres no leakage from anywhere i can see when i pull up or when its left. Also (forgive me i'm not the smartest person in the world) by coolant reservoir you mean the bottle type i put it in? The problem was intermittent before but it occurs everytime i drive it now and i'll definetly look in to getting it replaced if thats the case. When i go home on holiday theres a Superb in a local scrapyard i'm planning on getting a new part off to see if that makes a difference


Yes, the reservoir is where you fill it up with coolant, with the hoses attached to it. What you describe definitely reinforces what the other poster said; the crack would get worse over time, and heat causing evapouration would in most cases eliminate any leakage. I'd follow their advice and replace it!
Reply 5
Original post by IWMTom
Yes, the reservoir is where you fill it up with coolant, with the hoses attached to it. What you describe definitely reinforces what the other poster said; the crack would get worse over time, and heat causing evapouration would in most cases eliminate any leakage. I'd follow their advice and replace it!


Sounds pretty logical to me! The Superb i'm robbing the part off of this weekend is the 130hp version of the engine (mines the 110hp) but by my limited knowledge the only differences really are the management systems and the internals (pistons etc) but other than that they're exactly the same engine. Will let y'all know what the outcome is!
Original post by Y333EEE
Sounds pretty logical to me! The Superb i'm robbing the part off of this weekend is the 130hp version of the engine (mines the 110hp) but by my limited knowledge the only differences really are the management systems and the internals (pistons etc) but other than that they're exactly the same engine. Will let y'all know what the outcome is!


Check the radiator for damage. This could easily have a hole in it and you wouldn't even notice as the radiator is hot, the coolant evaporates while it's pouring out.

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