My brothers 1986 2CV suddenly started to leak oil .
First thought was the pressure in the crankcase.
We did the test with the hose filled with water and it was clear that there was no underpressure as should be.
We replaced the oilfiller as we suspected it from not working well, but this was not the solution .
So we went to the 2CV specialist and got two new oilfillers to test. With both the leaking continued and there was overpressure.( both tested by the specialist before !)
My brother decided it could be the piston rings ,so to be on the safe side , he bought new barrels, pistons and piston rings and new seals as well.
the engine still leaks badly and there is pressure in the sump.
Any-one any idea what the course could be?
The leak started suddely, so I wonder if there is an obstruction inside one of the oilpassages in the crankcase.

Where is it leaking from?

Both front- and backside seals.

Well that does appear to be breather related. Though the new barrels and pistons won't seal properly until they are run in. Are you perhaps able to swop with one on your 2cv and see if that cures it?

Hi Geert, 2 things to check. Is the oilpressure release valve working Under the righthand cylinder. Little piston in there must be able to move. Is the tube linking the dipstick to the oilfiller ok.

My brother just told me , I made a mistake, it is just the front-seal that leaks , the one on the clutch-side is oké.

Dipstick tube link is a good call, I hadn't thought of that before.

It seems that it is solved !
Dipstick tube link was bend.
It is not driven yet, but the pressure looks good while trying it stationary in the driveway.
To be continued .