Disco 2 Td5 Big coolant loss

Hi
My recently purchased Td5 is loosing a large amount of coolant, a 10 mile journey will account for about 1 litre, so at the moment i am down to very short journeys.
If i drive very carefully so the temp gauge hardly moves no water is lost so i wonder if it only happens once the thermostat opens.
I have put a uv dye in the coolant which i have had great success with tracing leaks in the past in several vehicles but this time nothing shows, I am checking the engine oil constantly and the level is not going up nor is the oil milky so i assume the water is not going into the sump, also there is no sign of dye in the exhaust so i do not suspect head gasket, plus no white smoke.
One thing i am wondering is there are two pipes in the coolant tank neck, one of these i don't know where it goes but the other seems to be a overflow, when the engine is up to temperature this pipe seems to drip, and the only dye trace is below this, could this be where the water is going and if so why ???.
Thanks for your time.
Bill

Have you checked the coolant tank for small cracks around the top ?

Yes, no visible sign of cracking or any dye tracks

Check the water pipe under the turbo,

Depending on age, it either has a 2 inch long rubber connection pipe from the oil cooler to a return pipe around the back of the engine or it has a blanking plug in rubber.

Both fail over time and perish.

Cheers

If it were me, I'd run from cold with the cap off the expansion tank and see what happens with no pressure in the system. Take it from there

kermit_rr said:

If it were me, I'd run from cold with the cap off the expansion tank and see what happens with no pressure in the system. Take it from there

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Hi, can you tell me what your thinking is behind this and wont the water just slosh out ??, thanks Bill

Billybones said:

Hi, can you tell me what your thinking is behind this and wont the water just slosh out ??, thanks Bill

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He's not totally wrong at all, the thinking is that the caps often fail.
He could have said just loosen it a bit and tape it down to stop it falling off.
But I'd deffo investigate all the pipes as mentioned above as well!
Best of luck!.

With the cap off there will be no pressure in the system which means the boiling point stays around 100c, or just below.
Yes the water pump will stir the water around but there shouldn't be enough movement while you're stationary for there to be any loss through the opening. If there is then you've got a big problem, either failed head gasket, cracked head or some kind of blockage air lock etc

My point being, with no pressure in the system your starting from scratch.
If everything ticks over nicely then there's no major issues.
If it starts getting too hot then there could be a blockage somewhere.
Start at A and work thru to Z

Ah I think i understand now, so the cap can stop sealing down the thread (where the overflow pipe is) and constantly let steam out, so if the cap is not sealed no build up of pressure, therefor no steam.
Tomorrow i will try this and also follow the pipes neilly has suggested.
Thank you all for the help.
Bill

With no load on the engine, ie at idle and turbo not dining etc, especially with a diesel, you shouldn't get up to boiling point.
The cap is there to protect from boiling if/when you overheat

kermit_rr said:

With no load on the engine, ie at idle and turbo not dining etc, especially with a diesel, you shouldn't get up to boiling point.
The cap is there to protect from boiling if/when you overheat

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Agree with all this.....
BUT often a problem will only rear it's ugly head when the system is under pressure. and what creates the pressure is the cap, designed to allow the coolant to heat beyond 100 degrees without boiling. Can get as high as 130 degs.
Don't know if I have ever heard of this magic colouring stuff that can even show if coolant is coming out of the exhaust, but i am prepared, as always, to learn something new.
Anyway, see if any of this helps.
https://www.google.com/search?q=how...me..69i57.13465j0j15&sourceid=chrome&ie=UTF-8

kermit_rr said:

With the cap off there will be no pressure in the system which means the boiling point stays around 100c, or just below.
Yes the water pump will stir the water around but there shouldn't be enough movement while you're stationary for there to be any loss through the opening. If there is then you've got a big problem, either failed head gasket, cracked head or some kind of blockage air lock etc

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Time to back flush the rad and heater matrix ...

kermit_rr said:

With no load on the engine, ie at idle and turbo not dining etc, especially with a diesel, you shouldn't get up to boiling point.
The cap is there to protect from boiling if/when you overheat

Click to expand...

There is a thing you can fit to the system that pressurises it without running it ...BERGEN 26 Piece Coolant Pressure Tester And Refill Kit Purge Refill Vacuum System is one, or you could bodge your own with a spare tyre and a spare rad cap, drilled to suit ...

"Don't know if I have ever heard of this magic colouring stuff that can even show if coolant is coming out of the exhaust, but i am prepared, as always, to learn something new."

Hi thanks for reply and link.
Both wurth and ring sell the uv dye, i find the wurth one is best and normally run it in all my vehicles from when i first get them, they also do them for engine and gearbox oil and aircon systems, great idea as all you normally need to do is have a look in the engine bay or underneath after dark with a uv torch and look for the florescent glow, then follow it to the source.
have had it the past when my old 200tdi was loosing water and spotted florescent spots in tailpipe, sure nuff head gasket on way out, not sure how long it can stand up to engine temp though but i think i got lucky
Bill

Dippypud said:

There is a thing you can fit to the system that pressurises it without running it ...BERGEN 26 Piece Coolant Pressure Tester And Refill Kit Purge Refill Vacuum System is one, or you could bodge your own with a spare tyre and a spare rad cap, drilled to suit ...

Click to expand...

I've got a pressure tester, fantastic piece of kit

kermit_rr said:

I've got a pressure tester, fantastic piece of kit

Click to expand...

I know right ...

Secure a bottle over the short overflow pipe on the resevoir and see if it catches the water. If so I think you'll find you need a new pressure cap and it needs to be tightened well.
Griff

Well chaps a update
After a lot of time crawling over it and under it after dark with a u.v torch nothing was found, so today i tried this
"Secure a bottle over the short overflow pipe on the resevoir and see if it catches the water. If so I think you'll find you need a new pressure cap and it needs to be tightened well.
Griff".
using a 1/2 pint (500ml to you youngsters ) milk bottle, went for a 15 mile drive, got home and found the milk bottle was FULL .
I assume the cap is not sealing around the thread and is allowing water to be constantly be forced out under pressure ???.
Do I just need a new cap or could there be a bigger problem ??, is it normal for there to be that much pressure to constantly force water out of the overflow pipe ??.
Sorry for so many questions but this is quite worrying to me.
Thanks
Bill

Check if the pipes are rock hard at this point