Smoke and hissing!

I already did a search and was not able to find an answer…This is the problem…Whenever I accelerate pass 4K rpm, I get a loud hissing sound from under my hood. I took it to a mechanic who was not able to figure it out so I took it to the dealer. They told me that it was from the aftermarket alternator I had installed. Apparently, there was a faulty brush. I had a new alternator put it, but it still makes that sound. Also, I notice a lack in power when speeding up. Also, there is now white smoke coming from the exhaust at times. What I found out from the search is that it may be coolant and I might need a new head gasket…But what about that hissing!!! It souunds like mad rattlesnake is trying to come from under the hood…

Thanks for any help in advance…:rant:

from the sound of things it leads me to belive its an air leak on the intake manifold. check all your hoses and even the intake to head gasket for leaks.

thanks. i will check that out. any ideas on the best way for a non-car guy to check that?

pretend your a car guy ?