Whenever I start my truck, for the first 2-3 minutes there is a very clear and distinct hiss that's seems to be coming from the truck. It doesn't matter whether I park outside (-20C) or inside, it's always there for a few minutes before going away. When the hiss is there, accelerating will cause it to rise in volume. It's been manifesting itself more since I put a K&N cold air intake in, so I'm not sure if that has anything to do with it or not (I check everything I did and I don't think there are any leaks). Any suggestions on what it could be? Or the best way to search for the problem? Thanks.

 

I ONCE HAD A Found On Roadside Dead THAT HAD AN INLINE 6 CYLINDER. THE INTAKE AND EXHAUST MANIFOLDS SHARED THE SAME BOLTS. LONG STORY SHORT, MY INTAKE MANIFOLD CRACKED AND CREATED A HISSING NOISE BUT... IT WAS A SMALL CRACK SO WHEN COLD IT WOULD LEAK BUT WHEN IT GOT HOT THE METAL EXPANDED WITH THE TEMPERATURE ANDTHE CRACK CLOSED UP. SO I RAN SOME SEA FOAM THROUGH THE MAINVACUUM LINE TO THE INTAKE, (SUPPLIESVACUUM TO THE PWR BRAKE BOOSTER), ANDTHE SMOKE CAME OUTTA THE CRACK SHOWING ME WHERE MY LEAK WAS.

HOPE THIS HELPS!

 

mine did it too. what it is the idal air contol valve is sticking. just take it out and clean it or replace it

 

mine does it too, i just let it do it since it only lasts a little bit, sounds like a jet taking off...lol.

 

Cool thanks for the info. I was just worried that it might be something that could cause lasting damage. From what I read it probably isn't a great thing, but nothing to panic about. I'll have to take a good look over the holidays.
Cheers.

 

most of the time puttin in a CAI will cause that hissing noise. my 2001 started doing that after putting on my AIRAID. its normal, its just because it's sucking in more air.

 

yea, i flipped the lid back over last night and started it up this morning and the hissing was coming out of the grille, so it is just the air filter making it louder while it issucking more air while the engine is warming up.