New Upper Radiator Hose Leaking Coolant

[bimmer48i]

Hello all,

I recently decided to completely overhaul the cooling system in my 2009 E70 4.8i xDrive (N62B48). This included,

1. Expansion Tank and cap (1.4 Bar)
2. New cooling system hoses including Y hose under throttle body
3. Geniune BMW Water pump
4. Mahle Thermostat (90c from ebay)
5. Bimmerfix Stent

I installed everything, connected all the hoses properly until I heard the click sound. Filled it with BMW Blue Coolant mixed with distilled water.

Initiated the self-bleeding process, and filled her up. Drove for 10 minutes around the neighborhood, came back and parked the X5.

After it cooled down, I checked the coolant level in the Expansion tank and it was low. It wasn't low enough to throw the 'Low Coolant" warning but low. I added the coolant again, drove for 10 minutes and same thing happened again.

Performed a pressure test and turned out the coolant is leaking from upper radiator hose where it connects to water pump. I removed the hose, inspected inside and there was no debris or anything. The water pump surface is clean too, since they both are new and Genuine BMW parts.

I connected the hose until I heard the click sound again and filled the coolant. I even double checked that the hose was connected properly into the tiny slot it has. Unfortunately it still leaks in that place.

I've exhausted all my options that I knew of. Any help or pointers would help.


Sorry about the long post; it's my first post.