Coolant leak

[52vincent]

On my '92 535, it looks like I'm leaking coolant from the fitting below the upper radiator hose for the line that circulates coolant to the transmission. I'll be dipped if I can tighten it. Any thoughts? Is there an O-ring in there? Is it just a metal-to-metal connection?

[whiskychaser]

On my '92 535, it looks like I'm leaking coolant from the fitting below the upper radiator hose for the line that circulates coolant to the transmission. I'll be dipped if I can tighten it. Any thoughts? Is there an O-ring in there? Is it just a metal-to-metal connection?
There is an O ring in there:
http://www.realoem.com/bmw/showparts.do?model=HD23&mospid=47408&btnr=17_0114&hg=17&fg=05

[Ross]

The o-ring shown is to seal the trans fluid cooler line.
I think he is leaking coolant where the oil cooler is in the tank.
I've never dealt with a leak there(jinx) but suspect the tank will need replacement unless the oil cooler is removable so has some sort of replaceable seal to the tank.