Coolant leak driving me nuts?
 

W124-M104.992 engine. 94 E320 Sedan.
I have a coolant leak. Replaced all 3 radiator plus the back drivers side heater hoses last week. Also replaced oil filter stand gasket (it was leaking oil ). Thought that was the end of it.

Still leaking. It's apparently in the vicinity of the back drivers side corner of my engine where the heater hose connects. But I NEVER actually see it leak! Even after driving and using an inspection mirror. That area is VERY hard to inspect : (
There is dried coolant waters stains (white) on top of that hose and all around the oil filter stand.

Help...

The short pipe that the heater hose clamps onto has an o-ring that seals it to the cyl head, and could be leaking.

Did not know that.
How hard is that to repair?

Not too bad, especially if you have swivel 5mm and 6mm allen sockets. Egr pipe is clamped to the bracket/pipe with a 5mm allen and two 6mm allens secure it to the head.