V5 coolant mystery

I was loosing a large amount of coolant- the max to min line, in about a week.
I got the car pressure tested, and the only leak they found was a small rubber seal to the heater matrix was split- so it was replaced.
They retested the car, and no leaks.

Ever since then, i have still been loosing coolant- but at a much reduced rate. In a 2 month period it lost from the max line to the ridge in the bottle. Now i would be happy to accept this as normal usage if you guys have experienced similair stories but my old car never used a drop, and if it did it was over 6/7 months or so.

My only other thought, was that it was the bottle top. As it looked worn and it came off and screwed on a little easy. I have since got a new cap from Seat which looks to be a newer design and it fits alot more tightly. I have topped up with G12 as of this morning so we will see how it goes.

If it still loses some though, does anyone have other ideas????

As said its been tested twice and they cant find any leaks. To be honest its becoming a bit annoying now and marring the ownership experience a bit.


Cheers guys

Oil and water not mixing, and no loss in performance or overheating so im 99% sure its not the HG. Im not sure about the bottle as its pretty filthy so i wouldnt know about any marks.

I did wonder about WP as i have no receipts for it being changed. Rad looks in good nick too

Reading through that- his was the pump, but i have none of the syptoms he had apart from the loss of coolant. I may just get it done anyway just in case as its only £140 or so at the local VAG specialist

meltonlad said:

mate mine has turned out to be water pump broken up and in turn its done my HG in so now im looking at over £900 for repairs.... my temp never went over 90 still running like it should and it all started with loss of coolent. if you remove your thermostat stick your finger in the hole to the left you will feel the pump. but please do it when its stone cold. thats how i found out my water pump had gone.

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That a V5 though? The pump is nowhere near the 'stat on a V5

Right, i have driven over 400 miles since the topup and new cap.................. and it hasnt moved! It is hard to judge exactly as i never did it right to the line. Its annoying how the right hand side of the bottle shows higher thand the middle/left!

Just to make sure, i have made a few pencil marks at where it shows around the bottle and i will keep checking it every day (going to wear out my bonnet catch at this rate!!!)

It may be the case that the leak is tiny, and 400 miles wasnt enough to make it move- but we shall see! Looking better than before anyway though

AJ-V5 said:

Right, i have driven over 400 miles since the topup and new cap.................. and it hasnt moved! It is hard to judge exactly as i never did it right to the line. Its annoying how the right hand side of the bottle shows higher thand the middle/left!

Just to make sure, i have made a few pencil marks at where it shows around the bottle and i will keep checking it every day (going to wear out my bonnet catch at this rate!!!)

It may be the case that the leak is tiny, and 400 miles wasnt enough to make it move- but we shall see! Looking better than before anyway though

Click to expand...

Right, checked again today. its not fully cold yet- but it looks good! Its above the pencil marks at the moment because its not cold but it isnt far off so i will check in another few hours. Cant believe a £7 cap could have been causing such an annoying problem.