Hey guys,

This has been a long term problem I've noticed for about a year. 2000 Dodge Ram 4x4 5.9L new tranny and torque converter (so I ruled out those two components). While driving with normal acceleration, everything sounds fine. When I accelerate just a little bit harder, say about 1/4 - 1/2 throttle, I hear a noticeable hissing. If it's a hard acceleration, say harder than 1/2 throttle, the hissing goes away. Everything seems to operate fine. It does it in 2WD or 4WD, makes no difference. It runs fine and doesn't hesitate or anything. Oil pressure is good. Any other info needed, please let me know.

My friend's 2003 GMC 2500HD 6.0L did the same thing, but not nearly as loud. I know that these are trucks and that they make noises, I was just curious if this is a symptom of anything. Thanks for the help!

 

I have the same problem. I wish I could help ya

 

try changing the TB gasket ( throttle body to manifold) or maybe the plenum is leaking.
mine needs plenum gasket replaced badly, its in schop right now getting new tranny, wish i could give you 100% positive answer but that is kinda a guess.

 

My friend had the TB gasket go bad. It idled very high due to the extra air. I'll check it when I get a chance.

 

or it could even be just your hearing the air rushing thru the TB, mine has that sound cause of the metal intake and TB spacer(junk)

 

Would a bad plenum gasket cause low oil pressure? My oil pressure is superb.

 

No ... but it usually causes you to use a LOT of oil in short order.

 

That's wonderful. Because my truck uses NO oil. I might get lucky with this whole plenum thing.

 

Hissing under acceleration...probably a misalignment between your air filter box and T/B, or your air box to T/B gasket is missing.
If you have a K&N, try lifting up on the tube down by the filter. If you see a gap between the T/B and the tube, thats your hiss. It doesn't take much motor flex under acceleration to do this.

 

My truck is usually like a quart low when I go to change the oil