[Simonlane1]

I have a 2015 plate Skoda Octavia VRS which has done 180k miles.

Lately it has been slowly using more and more coolant, so I arranged for a system pressure test which diagnosed that the water pump and the expansion vessel needed replacing. These components were replaced along with the timing belt, and the pressure test result was positive.

Within 500 miles of this I had to top-up 2 No. litres of coolant, which is more than I was topping up previously. Thinking that it must then be the head gasket, I did a DIY home-test for combustion gasses present within the coolant, using one of those kits you mount on the expansion vessel and wait to see if the blue liquid turns yellow to indicate the presence of combustion gasses, but the result was negative.

Surely on a pressure tested closed-system with new parts, the only place 2 No. litres of coolant can be going every 500 miles is into the engine via the head gasket ?

Are there any other tests which can be done prior to stripping it down and inspecting ?

BTW - The engine runs like a dream interestingly enough and never overheats !

[Marc]

Hi @Simonlane1
Welcome to the community! Thanks for posting 👍
Sorry I can't help at all on this subject. Did it get sorted?

[Saminiri]

@Simonlane1

Hi,

It does indeed look like an internal leak, but before you disassemble, try these checks:

Check for exhaust steam as a leaking head gasket can cause persistent white smoke, especially when cold.

Check the oil; If it turns milky, coolant could be mixed in.

Re-pressure test again to look closely around the radiator, hoses, and connections for any micro-leaks that you can't see when hot.

Engine block test as some garages can detect minute traces of exhaust gas in the coolant better than home kits.

Good luck😊

[Rolebama]

Was the system bled properly after the new water pump was fitted? Sometimes it needs a bit of driving to get any airlocks out.

[Rolebama]

Just noticed how old this post is.