Noice on decel

[TJCTalon]

Okay so since I connected my downpipe to my cat back (was just running open DP) I get a wierd noise on deceleration. It was probably happening before, but because of the open downpipe, I couldnt hear it.

It vibrates and makes odd sound. Cant really describe it. To me it feels like it may be the driveshaft or rear end. But Im pretty sure it only happens on decel. Do you guys have any idea what it could be?

Is there anything specific I should look for?

Thanks,
Taran

 

[eclipsh]

Lots of things could be the culprit. It could be gear or drive shaft noise, worn clutch noise, rubbing, heat shields etc. Your best bet is getting under the hood, revving the engine and listening while it spins down. If it doesn't happen then your next step is getting the car up in the air and checking things out. Engine breaking can cause some rattling in the transfer case or rear end if the lash adjustment is off. The transfer case can make a lot of noise if the bearings are going out due to the notorious oil leak.

 

[TJCTalon]

What do I look for when checking the T case? Are there barrings on the driveshaft that can go bad or anything? I was planning on doing all the gear oil ( tranny, Tcase, rear diff) here in the next month or so.

 

[eclipsh]

A good start is making sure the transfer case oil is full. If it is low you may want to drain it and look for metal in the fluid. Lots of metal or chunks means you'll need a new t-case. Do a search for transfer case recall on the site and you'll find lots of info on it.

The drive shaft has three u-joints which can make noise if they are going bad. It also has a universal joint which could wear out and two carrier bearings which wear out. It isn't likely that the carrier bearings would cause noise only on deceleration but the others could. You could also have worn bearings in the rear differential. Look for lash adjustment in your service manual if you suspect it is the rear end. It should tell you how to check for excessive play.

 

[3kgt2nv]

What kind of noise is it? Is it a scraping, grinding, whirring, does the car do anything else like have wobble in the steering or in the shifter, does it knock or bang?

 

[TJCTalon]

It just vibrates the car and as wonk wonk wonk sound but its not really that loud. It seems to be coming from directly below me. But the car does not make any sounds like that on acceleration.