DO NOT MOVE THIS POST!!

No there are no snakes under my hood! LOL

But with the engine idling I hear a hissing sound from the front passenger side head emmenating from the front edge of the head. I can localize it to about a 12" radius area but I can't figure out where it's coming from.

Before I pulled my plenum and reshimed my valves, I thought it was the valve cover leaking....But with 100% non leaking valve covers, new PCV valve and PCV mod it's still there...

Any ideas? The truck idles fine...

259,931 miles at present...:d

 

Do you have a supercharger on there? sometimes the supercharger will have a little more air intake noise.

 

Please tell me you just didn't say that. No one makes a supercharger for the 3.0. Also that would be a pretty obvious thing. Also all the intake stuff is on the drivers side.

 

you sure its not a vacume leak

 

(I wish my 3.slow had forced induction...lol)

Yeah, I am 99% sure that it's not a vacuum leack. I recently pulled the intake plenum and made sure that every hose was accounted for and in place. Its not the valve covers or PCV valve... If an exhaust manifold were leaking it would be a pulsating hiss and not a continuous his like I have?

 

From my exp. I always thought that exh leaks under hood were accompanied with more valve train noise as also.....frnt pass side I think the reed valve and EGR are just behind that area and that would be right around the area of the P/S pump. Front side start into the timing belt area. Not be a smart butt here...you sure it is an air hiss and not a belt or bearing whine that you are hearing. Does it change with RPMs or is it constant?

 

Maybe it's just inner ear damage ( 159.8 db @ 42 hz )

 

yes, the reed valve is towards the back of that same cyinlder bank, but the EGR and EGR modulator are right there next to the PS Pump...

I thought that both belt whine and bearing whine would be a squealing noise? I haven't tried listening at different RPMs. I'll do that today.

 

Take pic of the area you think it is comming from. Somebody might be able to look at it and give you some things to check.

 

try getting a piece of old tube, I use a garden hose, and using it like a stethescope (sp) just put it up to your ear and move that bad boy around the engine bay till the noise is the loudest.

 

LOL, nope I am not one of those idiots you hear bumping down the road. In fact very few people even know that a system of any kind lies behind the 5% tint....

I do have minimal ear damage however.

Steve

 

header gasket??? that might be it...anyways i would imagine you have hearing damange...120db is harmful to the human ear...159.8 db...well...self explnaitory

 

Does the engine idle rougher/lower than normal? A few months back, my idle dropped and the engine was running a little rough. I could also hear a hissing sound from under the hood. Turns out it was a PS vacuum hose that had dry-rotted and finally broken. There are like 500 little vac lines around that PCV.

 

I've also got a hissing sound that seems to be coming from the passenger's side and I can't figure it out either. I haven't lost any fuel economy, but have noticed that the engine is vibrating a little more during idle than it did before the hissing sound started.

Troy

 

My vote is for a vacuum leak. BTW there is no way leaking valve covers are going to hiss...