Alex has already clearly defined where to blank the egr at its inlet. If it's the egr leaking then the coolant mus be draining either back into the exhaust manifold or into the top horseshoe pipe that curves over the engine top to the throttle body.
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Alex's blank is just a piece of clean flat metal with a few holes. If you follow the same principle you could also blank off the horshoe pipe at the engine front where it bolts to the throttle body thus leaving a 'tube with blocked ends' between the exhaust manifold and the inlet manifold. Use silicone gasket sealer on the home made blanks.
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The double blank will be a very low cost piece of engineering. It has the advantage short term of not messing with the water hoses.
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run like that for a week and monitor coolant loss. At the end of the week undo the front egr pipe at the throttle body. If the egr is then culprit then water will flow out of the blanked off pipe as you undo it.
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Kind regards from Fred. 2010GS Auto ex Celeb, Santorini Black, 2011 facelift , spoiler, spats, mudflaps, LED footwell lamps, Witter detach,
Other cars:-
1958 & 1959 Austin J40 Pedal Cars under restoration (I make many J40 parts)
If you have an Austin J40 or Pathfinder Pedal Car looking for a new home pls PM me.
2009 Meriva

Short update -

No smoke white or otherwise from exhaust when hot whilst engine revving, with any luck head gasket ok.
No bubbles from expansion tank with exhaust blocked.

Not totally conclusive of course so waiting for test kit to come through post to check for exhaust in coolant before draining transmission fluid etc.

Regards
Tony

Did you thought of a small leak, drop by drop, on something hot, like exhaust for example, only happening when the system is under pressure - engine hot - and therefore you wont see something obvious?
Indeed, wont account for that black thing in expansion tank, but...

And a thought.... The line pressure on autobox lines is generally over 20 psi, reaching almost 200 psi in some cases, so the transfer of fluids are, for sure, from oil to water and doubtfully from water to oil... So I don't believe the transmission oil will be contaminated... Yes, maybe when you stop the engine and the water is still under pressure, but I don't think you are so unlucky...

Presumably you've looked for visible leaks - coolant staining at joints. Possibly also water pump? These normally only leak after switching the engine off. Again staining, or drip if serious, should be visible. Ex AA Series III LWB Safari - Gone
300TDi Disco (bought new - terrible car) sent back after 18 months
Freelander 1 Estate - leased, given back at end of lease
200TDi Disco (bought from a mate with 100,000 on the clock) - Gone
Disco 2 TD5 - sold and exported to France
FR2 TD4 GS - Gone
FR2 SD4 HSE - Now changed for a DS
New model ex-demo Evoque S 180 in white
Unable to order a new DS, so gave up. Now have a Volvo S90 Recharge.

Yes I've had a good look from above and underneath but no staining visible. I had the offside inner wing off to try and detect leakage from the water pump but the cambelt cover would need to come off to see properly. As Alex pointed out though a simple leak doesn't explain the deposits in the expansion tank. Thanks for the suggestions though.

More thoughts.....
Use kitchen towel and take two sludge samples from the header tank. Use a hair dryer and dry them out. Do they look sooty or oily? Take one dried out one and drop it in water; does a clear oil film form on the water?
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I just wonder if it might show if you have oil in the water or combustion carbon.
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Have you thought using radseal?
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Kind regards from Fred.
. 2010GS Auto ex Celeb, Santorini Black, 2011 facelift , spoiler, spats, mudflaps, LED footwell lamps, Witter detach,
Other cars:-
1958 & 1959 Austin J40 Pedal Cars under restoration (I make many J40 parts)
If you have an Austin J40 or Pathfinder Pedal Car looking for a new home pls PM me.
2009 Meriva

Thanks for all the ideas and apologies for the lack of updates.

The paper towel idea was interesting, the dried deposits appeared to be carbon rather than oil. I also syringed some coolant from as near the surface as I could and squirted it onto a hard surface and let it dry naturally, soot like deposits were left.

The combustion gas tester indicated that no exhaust was present at the expansion tank but I think it would only show exhaust gas if the head gasket had blown. I tested it directly at the tailpipe and it took a few samples before the solution indicated exhaust present.

So next week it's booked in to have the EGR cooler bypassed as described by Alex. Hopefully in a couple of weeks I'll be able to say whether the EGR is the cause.

Cheers Tony

Well still looking for advice I'm afraid!

Coolant still disappearing and black deposits in expansion tank, so not egr or cooler.

Drained 0.7l from transmission,engine not running, looked fine just slightly darker compared to a year ago when I changed it.

Booked it in with local mechanic for oil cooler change have run it for a week and still losing coolant!

Slightly fed up now especially as steering pump starting to whine!

Alex stated that due to transmission fluid pressure direction would be fluid to coolant not other way round.

So could it be the transmission cooler losing coolant? However where is the coolant going if the transmission fluid level is staying constant?

Guess I should bypass cooler as Alex suggested.

All advice gratefully received.

Regards Tony

Have you checked to see if your water pump is leaking coolant as it could be failing and splashing the cambelt.
I also found on my engine that one of the radiator hoses rubs on the cooling fan wiring loom check this as there is a braded sheaf on the hose but it still rubbed through creating a small pin prick hole that leaked under pressure.

The water pump I've checked by taking off the inner wing and staring at the crankshaft pulley area, all looks clean.

I'll take a look at the pipe near the fan as you suggest, when the engine is nice and hot.

I'm thinking that the coolant leak has been present for a while and the oil cooler just happened to fail recently. There's still oil in the coolant but hopefully that's from the failed oil cooler so some system flushing with Wynns extreme degreaser will sort things.

Regards Tony

Hi folks. I would like to share a story regarding my FL2 07`.
It started with a coolant loss issue. My good friend handed me a bottle of leak fix that I poured into the coolant tank and let the engine run for a few minutes with heater on. This did not fix my leak but made me replace the heater register. Driver side gave no heat.
This is when the DPF trouble started. The car went in and out of garage for over a year. It would not regenerate.
I replaced EGR that eventually stopped the leak but still no regeneration.
I replaced, DPF sensor, intake, sensor pipes (in and out of DPF filter), DPF filter, remapping and so on.
This continues for som time and many limp modes. And loss of power even not in limp mode.
Until I asked the garage to check the cruise control. This had been out of order since replacing the heater register.
Then the technical guy found a loose bracket for a engine control switch over the brake and clutch pedals.
He fixed this bracket and the car is as new.
So, this tiny fault causing so much pain.

Hi Tpot,
Did you find a solution for this issue?
Thanks, K.

Hi, Yes, it turned out to be the engine oil cooler. Somehow oil leaked across to the coolant but not the other way round since the oil level stayed constant and no emulsification could be seen on the dipstick or filler cap. Perhaps the coolant boiled when first coming into contact with the oil hence the coolant loss. I can't remember whether the gasket interface has both coolant and oil in which case perhaps the gasket seal could have been to blame?

I had already bypassed the EGR cooler to prove it wasn't that.

Cheers
Tony

alex_pescaru wrote:

A picture makes a 1000 words. Below is the EGR system. You can click on the picture to enlarge it.
You can't damage the EGR if you blank the exhaust exit from the exhaust manifold.
I've pointed out with red arrow where you can blank it.
And then directly connect the hose from (5) to the hose from (7).

Click image to enlarge

Hi alex i need to close the intake gas to the egr cooler, i have a fluid loose because of a break of the cooler, so in this moment i have made a bypass of the refrigeration circuit , but i need to close with an adeguated blanking plate; do you wnow what is the meausure of the intake gas into the cooler?
thank you