BKD 140 TDI losing lot's of coolant with no leak!!??HELP...

[Sjw_Vw]

As above - I've had my car into 2 different garages and they can't find a leak. They've pressure tested my coolant bottle, had my car in the dry garage for a few days to see if it's leaking(which it isn't) and done all sorts of other things to which they've had no luck finding a leak! On average I have to fill my coolant bottle from the bottom to the top every 200 miles(ish). It started all of a sudden a few months ago and has continued ever since. I'm quite worried about it in all honesty! It's a Mk5 Jetta 2.0 TDI 16V Sport PD140, which has just hit 96,000 miles. The engine runs spot on and is serviced every 6,000 miles with 5W/30/40 oil with all filters changed at the same time.

Can anybody give me a clue as to what in the hell it could be!!?? Thanks - Shane

[Beddie]

Early BKD 140s had a nasty habit of developing a porous cylinder head, coolant loss/usage with no sign of an obvious leak is a tell tale sign unfortunately 

Google 'BKD porous head' it's quite a common issue..

[xjay1337]

Bad times. New cylinder head time.
May as well forge it for a big turbo

[Dazst250]

1 of 2 places it goes either into the cylinders and burns off on combustion or into the exhaust through the EGR cooler and again burns off. This is why you cannot see where's it's leaking.

Get the garage to look in the cylinder bores and see if they look wet after standing overnight? You can usual tell if it's the EGR cooler cos first thing on a morning while it's burning off there will be thick plumes of white steam coming from the exhaust.

[USBulldog]

Cheap one to check first is the coolant bottle cap. My old MK4 TDi did this and the tiny pressure valve in the cap had gone, changed it and 30k miles later she is still going strong. Might not be that but def' where I would start :) and let's hope it's the £3 fix and not the £300 fix.

[Andy]

Check the egr cooler isn't leaking,As Jay mention the early ones are prone for porous heads

[Sjw_Vw]

Thanks everyone - I'll get all these things looked into