exhaust leak or axle bearing

Ok ther is a new noise coming from the rear of my car, and I have no idea what it is. It is directly related to engine speed, but only happens while it is in gear and under load, free revving it will not make the noise. Its sorta like a whooshing sound, like there is a lot of air trying to get through a small hole. It gets louder as the rpms go up, and if I give it more gas the noise gets louder also, There are no visible changes from before, as I already had a huge hole in my muffler. I was wondering what axle bearings or wheel bearings w/e is in the back sound like when they need changed, but then wouldnt it make the noise while coasting also? The other thing is the engine itself doesnt seem to be the source of the noise, as it is definintly behind the front seats. The only other thing I could think of is, is it possible to install a driveshaft wrong and have it slip? I just had a new clutch put in and to my amazement there was already a one peice on my v6, and although I dont know much I dont trust any shops, Im paranoid of them cutting corners.

Has anyone else ever had noises like that? Or atleast know about the driveshaft or bearing thing?

Please and thank you!!!

95slvrZ28 to the rescue!  I heed to your call from the Off Topic section!

If it's a wheel bearing it's going to make the noise at all times and it will be related to the speed that the car is moving, not the engine load or engine speed.  It sounds to me like you may have a hole in the exhaust, whether it visually changed or not, this doesn't mean something didn't rust through further and sprout an actual leak, or it could be on the top of a pipe.  The sound that your describing sounds a lot like an exhaust leak to me.  Go and get some drivethrough and when you're sitting next to the wall listen to your car and see if its making a pffft pffft sort of sound that is related to RPM.  

quote:

ORIGINAL: 95slvrZ28

95slvrZ28 to the rescue!  I heed to your call from the Off Topic section!

If it's a wheel bearing it's going to make the noise at all times and it will be related to the speed that the car is moving, not the engine load or engine speed.  It sounds to me like you may have a hole in the exhaust, whether it visually changed or not, this doesn't mean something didn't rust through further and sprout an actual leak, or it could be on the top of a pipe.  The sound that your describing sounds a lot like an exhaust leak to me.  Go and get some drivethrough and when you're sitting next to the wall listen to your car and see if its making a pffft pffft sort of sound that is related to RPM.  

 
Beat me to it.

Off topic is almost an advertisment section anymore....

Anyway, thats what I thought, if its an exhaust leak im not real worried, ive got an SLP catback its just way to cold to do anything to a car right now.... I hadnt thought about that drivethrough idea thats pretty good, I'll try that later... Thanks

I dont think its a leak anymore, it seems more like the exhaust is being restricted. And the car feels alot slower the higher into the rpms i go. Im afraid to take it past 3.5k now because its a sound sorta like pressure building, and I really dont want to see what the culmination of redline would be. Im taking it back to the tranny shop that put in my clutch and Im gonna ask them what all the helll they did. That, and I noticed it is audible at idle, I parked in my garage, put the door down to the bumper, and sat in there with it running for about 3-5 minutes and could hear it, its like a low whistle..... Grrrr.... And the last mechanic that looked it over before the clutch thing said it was in great shape for 104k miles, I sorta know him personally, and he said this is leaps and bounds above the LT1 I brought into him atleast once a month lol. Any help would be appreciated, ANY AT ALL!!!

Well, via screw driver and jackstands, I found the source. The catalytic converter, so I took it to autozone to get it scanned, because my light is always on for some EVAP stuff I cant afford to fix right now I didnt know a new code had been thrown, I didnt get the exact code, but inefficient/inoperating catalyst is what came up. Im guessing its plugged..... SOB.... Sooooo.... 02 sim or new cat? What do you guys think would be better for a peppy DD?

Are you asking whether to straight pipe it or get a new cat? The way that last part was worded, made it sound like a sim would get rid of the problem, which it won't. Personally, I would just get a hi-flo cat, but that's cause of emissions and such. EVAP code may or may not be related to the cat problem. There's a guy in the V6 section who has a problem similar to your's and his car has the EVAP code...

RED94V6 WHATS UP HOWS IT GOIN....
 
I ALSO NEED REPLACE MY CAT IT'S RATTLEING AND IAM SURE IT'S JUST GONNA COMPLETLY CLOG...
 
IAM ALSO THROWIN A EVAP CODE P442 SO IDK
 
SO MY QUESTION IS THE SAME NEW 02SIM OR NEW CAT...
 
THANX ANYBODY FOR UR INPUT////

All caps FTMFL 

I'd probably just get a nice high flow cat. Doesn't your SLP system come with one?

If the cat is ratteling or clogged an O2 sim ins't going to fix anything...

That being said I would probably recommend going for a good high flow cat, such as a Random Technology or a Magnaflow to fix the issue.

quote:

ORIGINAL: itcantbestephen

I'd probably just get a nice high flow cat. Doesn't your SLP system come with one?

 
SLP is a catback, not a y-pipeback. Slvr's recommendations for hi flo cats are good ones.

Ya I should have been clearer, once the exhaust cools I'm gonna go punch out the cat, an O2 sim is all of 34$, and a good new cat > 200$ sooo its a clear choice for me. No emmisions here so I couldnt care less whats coming out my tail pipe lol. Although I was looking and it looks like the cat is welded in? This is gonnna be fun... I'll take pics and make a good how-to outa this haha.

rev94v6 where did u find the 02 sim ima do it also...thanx

http://www.3800performance.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=O2-EMU&Category_Code=ES_H&Product_Count=16H
This is a good website for alot of things other than the exhaust parts.

good..... thanx for the reply

Ok the cat is welded to the y-pipe and pretty much everything else So now I dont know, should I use a sawzall and cut it out and simply replace it with a peice of 2 1/2" pipe? I know Im not going to replace it, way too expensive. So I thought that might work then with the O2 sim. 

You can just put a test pipe in the middle to bridge the two if you need to weld it, no harm there!

Well after some deliberation, Ive decided to go with this incredibly high flow cat from NAPA

I'll need to cut it down to size since its a universal fit haha. The O2 sim I'll order tommorow.

Did you ever get it strait piped? I'm having the exact same problems and am going in tomorrow to get my car scanned. My cats been going bad for awhile and i wanted to see if this fixed your problem. Thanks, Drew