Coolant Leak in Cold Condition (AFN)

Hello fellow enthusiasts,

During the major service (270,000 km), I discovered that there was a drop of coolant hanging at the junction of the coolant hose to the ZK flange (the one with the temperature sensor) when the engine was cold!
Upon closer inspection of the leak, by pressing and twisting the hose, several drops appeared .

Since the coolant level has hardly decreased in recent years, the leak in the system must be relatively small.

'I usually check all the clamps for tightness during each maintenance cycle, and the clamp in this particular location has always had a 'hard' stop (meaning it doesn't have that 'soft' feeling when tightening).'

I then installed a new hose clamp, which could also be tightened again with that same soft feel.
The examination of the original clamp revealed a small imperfection (indentation marks) precisely in the 'tightened position,' which prevented further tightening with normal force.

Due to the expansion of the hose when the engine is warm, the entire thing was sealed again.

So: Hose clamps should always have this soft contact point (which actually makes sense, right?).

Best regards, Oldi.

If a coolant hose connection leaks, there's usually coolant or crystallized residue from the additive between the hose and the connector. The only solution is to remove it and clean it, and if necessary, replace the hose. VW specifies a torque of 2 Nm for tightening the hose clamps. In my opinion, that's too low. Tighten it by feel, until it's snug. That's probably what you mean by a "soft" tightening.
hg
Herbert.