Having a nightmare with my Octavia VRS 2.0 TDI atm. Car is on 135k miles, I’ve changed the cambelt and water pump 2 months ago nearly, and it’s been losing coolant. No signs of leaks anywhere from the car, absolutely dry, nothing around timing area, nothing underneath.

I have done a head gasket test, was fine. Done a pressure test last week, was fine. Drained all the coolant system last week, refilled and it’s been losing coolant again.

Was losing about 1-2 inches every 10 days now I’ve flushed all the coolant out it’s losing approx. 2-3 inches every few days.

• EGR cooler?????!!

• Radiator????

• Heater matrix??? (Fans work fine)

• Charge cooler???

Any ideas or do I give up

Was it ok before the cambelt change?

6 minutes ago, ords said:

Was it ok before the cambelt change?

Not sure to be honest, Didn’t have the car that long to notice anything but I want to say it was, maybe was leaking a tiny amount but not noticeable. But I timed it all correctly and had genuine bits

Generally its either going to be hoses or the seal around the water pump has been knicked and is leaking. (edited) - can you use a boroscope, pressurise the coolant bootle and check the cylinders to make sure its NOT a leak in the gasket.

Next check the hoses to/from the waterpump and to/from the radiator and make sure they are all tight and aren't split. Also check the radiator isn't weeping.

The other place that leaks - will be the header tank cap - there are revised designs, because the original ones leaked. I've also recently replaced a header tank, because we discovered a micro-crack in the tank which was weeping coolant out.

Edited 8 April, 20251 yr by varaderoguy

37 minutes ago, varaderoguy said:

Generally its either going to be hoses or the seal around the water pump has been knicked and is leaking. To confirm its NOT the cylinder head gasket, take out a spark plug and check that it hasn't been steamed cleaned. If the sparkplug (and valves) looks like they are spangly clean, its a leak in the gasket.

Next check the hoses to/from the waterpump and to/from the radiator and make sure they are all tight and aren't split. Also check the radiator isn't weeping.

The other place that leaks - will be the header tank cap - there are revised designs, because the original ones leaked. I've also recently replaced a header tank, because we discovered a micro-crack in the tank which was weeping coolant out.

It's a TDI

3 hours ago, ords said:

It's a TDI

Ar&e - applogises - I've edited my original posting to make it more pertinent to a TDI engine - not a TSI.

Likely charge cooler from experience. Try get a borescope down the temperature sensor. Do a search on here, one useful threads. Or drop me a message if you need some guidance.

10 hours ago, ords said:

Was it ok before the cambelt change?

1 hour ago, T07 said:

Likely charge cooler from experience. Try get a borescope down the temperature sensor. Do a search on here, one useful threads. Or drop me a message if you need some guidance.

Won’t let me send private messages yet