For the past few thousand miles, my 2015 2.0TDI 184 Scout has been losing coolant at the rate of ~ 0.5ml/mile, and may be getting worse rather then better.

 

I have failed to identify where from.

 

Dealers have conducted a coolant system pressure test - Fine.

 

I've done a sniff test which is inconclusive - there are no bubbles rising into the tank and after aaaaages there is possibly some colour change as the coolant , but no clear result like vids I've watched. No apparent super-pressurisation or contamination in the coolant. I suspect false-positive and I obviously want to eliminate everything else first!

 

No traces of leakage around bottle, cap, hoses, or bits of the engine I can see, or collections in the undertray.

 

I haven't pinned down if it's worse during any behavior (regen etc.) 

 

My waterpump failed early, so pump and cambelt were changed ~4 years ago, In an ideal world the leak would be from there and I'd get them replaced a smidge early (the plan for the car is to keep ~5 years)

 

 

I have read *a lot* about coolant leaks on this engine and haven't sussed it.

 

 

So..... My question is - Is there anything bad I should know about putting UV tracers in the coolant?

 

 

Plan is to check everything first, in the dark, with a UV torch, clean everything up, then add a small amount of UV dye, increasing until I find the leak, or it's apparent that I'm not going to.

 

If the leak is post-engine, EGR cooler or something, would I get the faintest trace in water vapour out of the exhaust? If I ran through an absorbent filter? Or is that a non starter?

 

 

Safe & simply clever.

58 minutes ago, Jono said:

Is there anything bad I should know about putting UV tracers in the coolant?

Not as such; it's a well known and documented technique for leak tracing.

Various threads on loosing coolant on here  and your idea is a simple and effective one, if its leaking externally that is.

 

I have a similar situation but not as extreme, mine only looses a bottle of coolant every 4-500 miles so watching threads like this

 

if it turns out to be an internal leak these threads may help 

 

https://forums.tdiclub.com/index.php?threads/coolant-blown-out-from-expansion-bottle.483783/

 

 

 

Also as a newer point, Dark side developments the diesel Tuner posted on their Instagram only this weekend of a leak found in the charge cooler which when removed was clear as one of the inlet ports was spotless clean compared to the standard sooty diesel mess on the others  as the mini rad in their had failed, apparently bypassing the pipes on top can stop this leak and it can also be viewed by removing the IAT sensor and using a camera to see inside but this leak point doesn't appear to be as common on here as there are very few posts so worth bearing in mind if no other signs.