Goodaye all
Car is using/losing about 1/2 litre of water over 100 klm, that's what I putting back into water reservoir when engine has cooled, it seems to be pretty consistant amount of water. No visul leaks and no wet around hoses, all hose clamps good, hoses seem fine and also no smell of hot coolant also not overheating, temp stays good. Been doing this since new water pump put in, for 2 years nothing like this happened, just an occasional tiny top up. Any ideas? I have none except maybe cracked head but car starts fine with no miss, not using extra fuel and no water in oil.
Cheers

It has to be going somewhere . . .

Leaking reservoir?
Spitting water droplets out of the exhaust pipe, even when hot idling?
Wet passenger side carpet?
Dribble from front of engine, below the water pump?
Pool of water in engine valley?
Radiator cap not holding pressure and venting steam via reservoir overflow?

Thanks for reply
No
No
No
And no
As I said only started when new water pump put on. Radiator has had pressure test, is good, so not that either.

Only way to find this is to pressure test the system

You state the issue in your last line in the post above "As I said only started when new water pump put on" this tells me that there is an issue there, perhaps there is, while under pressure and motor hot a leak and by the time you get to looking for it the residue has evapourated

You can pressure test the radiator all you want but you need to pressure test the complete cooling system

Will do and reply when done.
Cheers

I had one of these mysterious leaks a long time ago.
Turned out it was a pinhole in a hose, with pressure there was a tiny jet straight onto the ground.

Anyway, the coolant has to be going somewhere, keep looking!

Yep, it surely is going somewhere. Bloody thing starting to drive me.:nuts: Box of matches are beginning to appeal to my inner pyromaniac.:badgrin:

Been done. Held pressure for 2 hours, no visible signs of leakage.

Pressure test been done. Held pressure for 2 hours, no visible signs of leakage.

Have you inspected the overflow bottle carefully?

Goodaye flyboy
Yes I have, no water is going into overflow at all, this I know because there is just no sign of any coolant in the overflow bottle-reservoir, just clear water from constant topping up, plenty green stuff, coolant, running around inside of engine and radiator.

Have you tested your radiator cap?

What colour is the engine oil? Open the oil cap and see if there is what looks like cappuccino milk froth on it. If you see coffee or whitish colouring in the oil and/or the cap has that froth then you have either blown a head gasket or the cylinder head is cracked...that could lead to using a lot of coolant in a short period of time.

Not in a third gen, very hard to blow the head gasket and add to this if you do get one of these motors hot enough to do this damage chances are it will not run again

Have you tested your radiator cap?

?????

?????

Very ??? had the same problem with my TH - took it back at least 5 times to the dealer I bought it from - they couldn't fix it - bought a $10 radiator cap from cheapshitautos - Fixed! and I also had no smell or overflow evidence with the old cap, can only assume small amounts of steam added up to loss of coolant over a week or so.

Thanks for the replies and sorry for not replying sooner, life got in the way.
@ stroppy, oil and water clean.
@ flyboy, Should have mentioned it was the among first things I checked, the cap I had on was about 2 year old, had a new one lying around, put it on and no change.
The coolant has to be escaping somewhere and I cannot work out where it would be. A trip into town for me is about 100 kays return, nearly all of it highway. The overflow bottle will go from the F mark when cold to the low mark when engine has fully cooled in that one trip, not over a period of a week or so. No coolant is being expelled into the overflow bottle-reservoir.
Thanks to all who have replied.