Coolant leak near oil cooler, cffb 2.0 tdi

Hi there,
I had a very slight coolant loss the past months, removed belly pan and traced the pink crust all the way up to behind the intake manifold.

cap/ressure release seems normal but after I topped up with 2l of g12+ concentrate it dripped a lot more and then stabilised tight for the last 2000 miles - even 38 degrees Celsius all day in traffic with aircon on.

My thoughts/hopes are that coolant was too diluted in the past and some water boiled through a release valve<?> or weakness in the lines.

https://ibb.co/0yTTVkC

this is the best pic I could get with an endoscope of the origin, if anyone can identify the area, greatly appreciated - to me its looks like a temp sensor or somewhat, but I've never been there in one of these engines...thanks.

I've seen the oil cooler itself leak on a few of these. Usually at the seal where it mounts to the engine block it becomes brittle and cracks, over time from heating/cooling.

Remove the cooler and look to see if there's a bit of it broken where the seal sits.

hi thanks,

I don't think its the gasket did you manage to check the picture? (endoscope coming in from the right on the bay).

I tried a "raw" pressure test by filling over the line with concentrate to remove the air buffer in the tank -no leak.

It seemed to leak at this spot when the coolant was a lot more dilute, can anyone say if this is a design feature of that particular part?

norbert442 said:

hi thanks,

I don't think its the gasket did you manage to check the picture? (endoscope coming in from the right on the bay).

Click to expand...

I looked at the pic but can't really make out anything from it...

The cooler has an O ring type seal rather than a gasket where it mounts to the block. I've seen the housing crack where the O ring runs, on a few of these.
If it were me and I had a leak in that area, I'd take the cooler off and inspect it before anything else to rule it out.