Tonight on the way home from work I noticed steam coming from under the hood while at a stoplight. 15 seconds later the low coolant buzzer went off and I pulled over and shut her down. I could see I had a massive coolant leak from the turbo area. I was only 1 mile from home so I walked into a gas station and bought four gallons of water. I topped it up and could make about a 1/4 mile before the buzzer would go off; pull over add water and repeat until I made it home. It took 3 gallons just to make it that one mile; the water would just pump out onto the ground.

I suspected one of the turbo coolant lines so I removed the airbox and the air pump to have a look; sure enough the upper line on top of the primary turbo had ruptured. It was a long time coming too because it was inflated like a balloon, then finally failed. Only a couple bucks to replace, but this could have been bad.

The perfect time to replace the turbo coolant lines is when you do the silicone hose job, as you'll be there already. Once the airbox and air pump are out it is simple enough to do. I consider myself lucky. It is impossible to see or feel these lines without removing the airpump; I recommend checking them the next time you are doing any work like changing belts, or the hose job. Rob Robinnette's site has a good pic of the lines; search for "turbo coolant".

 

Similar turbo coolant hose symptoms: after my 7 warmed up after driving a few miles, some steam would come from under the hood - sometimes. But then the steam would stop after a while. Closer inspection showed steam coming from the passenger side of engine, somewhere around the turbos. The coolant level was fine everytime I checked it. Never saw coolant puddles or coolant dripping from under the car, just steam - sometimes. Replaced both turbo coolant hoses and solved the problem, no more steam. The hoses were very hard, and bloated as mentioned above. The leak was so small that it steamed at first, then I guess the hose and pipe heated up and sealed temporarily.
I bought OEM hoses from Mazdaformance (http://www.mazdaformance.com).
N3A1-13-54X $8, N3A1-13-536 $4

I agree w DamonB - change the turbo coolant hoses any time you are working near the turbos. These 2 hoses are cheap and they will leak sooner or later.
HIGHLY recommend that you get long-handled angled needle-nose pliers to get the lower hose clamp.

 

yup, mine blew this summer as well. Good thing i was 2minutes away from the shop i was heading to anyway