1996 has a hissing noise under the car. It's gone at idle but if you rev it a little it starts hissing. It's not a gradual start like a leak would be. It sounds like a diaphram doing back somewhere in the vacuum system or something. If I put my head under the drivers door and reach in and rev with my hand it's loud. I havn't put the car up on ramps yet and done it but I'm wandering if anyone here has had experience with this. There are no check engine lights and the car runs great. It's due for a timing belt and water pump job within the next month or so which I'm going to be doing when I can afford the parts. If there was a vacuum leak somewhere causing the hissing I'm sure there would be a CEL of some sort. It sounds like it's coming from around the cats but I don't see how it would make a sound like that. Sometimes it will stop when you rev above a certain point but it almost alway's doesn't make any noise at idle. Any ideas?

-Kelly

 

exhaust leak.

 

I second that - an exhaust leak.

Dave Mac

 

Okay. I guess I'll pull the car up on ramps when it get's home tomorrow evening and crank it up when cold and feel around for a leak? Won't take long until it's hot though. May be able to see a burn mark or something if it is in close proximity to anything else.

 

If there is an exhaust leak, you'll probably also notice a somewhat gassy smell. Also, you should be able to feel air rushing out of the leak.

 

check the lower EGR tube, mine was leaking on the 97LS, removed the passenger side cat/converter, and lowered the rear crossmember and let the motor sag to get to the bolts. the cat took longer than the tube.