I was running the mav today and put some water in the radiator. Got the temp up and I reached through the door and cut it off but when I did steam started pouring out of the passenger side of the cowl, lots of steam. So, I cracked the tab on the radiator cap to help release the pressure and looked inside the car and found water pouring from where the heater core is. I guess the cow area has rust in it then ??? or the heater core is bad or the hoses could have come off the heater core ???
Steam like that is pretty much always an indication that the heater core has gone bad. There is usually a distinct antifreeze smell as well.
If you put water in the cowl and it comes out inside then the cowl leaks. If it's only leaking when it's running then I'd bet it's the heater core.
I think he's saying, "My heater core busted, but the steam came through the cowl outside the car and not just under the dash, does this mean I have a rusty cowl?" If that's what you meant Will, I'd say no it's not an indication of a leaky cowl, because your heater box connects directly to the cowl for fresh air, and if that flap is open (or even if it's not, probably) then steam would escape from the cowl on the outside too. If that's not what you meant... Yeah, in case you missed it, you popped your heater core. Hope your car didn't have factory AC or it's going to suck replacing that.
