I have a 2008 G37 s, and noticed some greenish crust on the upper hose in the area where it mates to the engine. I purchased a new hose, and about ready to change it, my question is does it have to be bled if just the upper hose is to be changed? I assume not much air would get it or much coolant loss. I dont want to make a mistake.

 

it wouldn't hurt i would change the clamp also as they get weak over time.

 

In a word, yes, you will get air into the system by swapping out the hose(s).

Get one of those lisle spill free funnels -

My own recommendation is since you'll already be doing half the job, do it properly and thoroughly. Replace the other hose, radiator cap, and depending on miles, maybe even the thermostat. When you drop the lower hose, the radiator will also drain. Otherwise, it's somewhat of a half @ssed job. Not a bad idea to change the drive belt out at the same time either.

 

Is the hose itself actually leaking or is the clamp simply loose or out of position?

And yes, you'll lose a significant amount of coolant changing out the upper hose and it needs to be replaced and the system bled of air.

 

what is the best procedure to bleed the system?

 

^^You'll find the answer here

D.I.Y. Installations/Modifications - MyG37

On the right hand side, "search this forum", type "cooling", 12th thread down.