89 xj noise

im not driving my xj due to a noise its making and am unsure where to look as i cant tell for the life of me where the sound is coming from, being inside the vehicle or out.

the noise is like a bad (or being destroyed) bearing whenever im on the gas. its the same kind of noise i had on my last truck before the wheel "detached" going down the road due to wheel bearing failure.

BUT, when i coast or brake there is no noise. i replaced the muffler thinking it was the baffles inside, as it was hit by a broken rear driveshaft, but the noise is still there. could it be the catalytic converter?

could it be an axle bearing even though the noise is inaudible when coasting? (the rear end oil does look to have some mud/water in it). maybe its something in the transfer case?

this is a stock xj besides having around 3" of lift and 31"tires. it has no noticeable driveline vibrations.

Crawl under it with a rubber mallet and give the CAT a few good whacks.

joe_peters said:

Crawl under it with a rubber mallet and give the CAT a few good whacks.

Click to expand...

to listen for movement inside? assuming the honeycomb is broken and i gut the cat, can i sell the innards?

i know rhodium fell from $10000/oz, but it's still a nice $2000/oz now.

http://www.kitco.com/charts/rhodium.html
http://www.kitco.com/charts/livepalladium.html
http://www.kitco.com/charts/liveplatinum.html

Ulver44 said:

to listen for movement inside? assuming the honeycomb is broken and i gut the cat, can i sell the innards?

i know rhodium fell from $10000/oz, but it's still a nice $2000/oz now.

http://www.kitco.com/charts/rhodium.html
http://www.kitco.com/charts/livepalladium.html
http://www.kitco.com/charts/liveplatinum.html

Click to expand...

Yes, listen for anything rattling.

I don't know if you can sell the innards of a CAT, but you should put another one in, and here is a link to the cheapest one I have heard of:

http://www.performance-curve.com/index.asp?PageAction=VIEWPROD&ProdID=1152

Another user found this part and installed it and was quite enthusiastic about it.

joe_peters said:

Yes, listen for anything rattling.

I don't know if you can sell the innards of a CAT, but you should put another one in, and here is a link to the cheapest one I have heard of:

http://www.performance-curve.com/index.asp?PageAction=VIEWPROD&ProdID=1152

Another user found this part and installed it and was quite enthusiastic about it.

Click to expand...

The CAT doesn't make any noise when smacked. Since the noise only occurs when accelerating, I'm thinking it may have something to do with the pinion turning up since that only happens under power. Maybe it's the pinion bearings? I don't know what else could make that noise only under power.

Ok, I put the rear on jack stands, cranked it up, and put it in drive. While looking at the rear driveshaft spin it seems to be wobbling a lot, and when I press the gas a little that noise occurs immediately - no tilt of the pinion or otherwise. The noise is coming from the driveshaft. Since there's nothing in the driveshaft it must be reverberating from one end, of which I can't tell.

I'm guessing there's no good/easy/cheap way to straighten out a driveshaft, so I guess it's time for hack and tap with a front cv shaft in the rear.

Also, when i push on the edge of each rear tire there's a millimeter or so of movement and a little clunk. Is that enough to cause problems? There's no play in the driveshaft but there is play in the rotation of the tire.

Ulver44 said:

could it be an axle bearing even though the noise is inaudible when coasting? (the rear end oil does look to have some mud/water in it).

Click to expand...

Maybe, you should be looking there. Growling when on the gas usually indicates bad pinion bearings or carrier bearings. Check your pinion for play without the drive shaft installed. There should be zero in/out play. Rotational, a few degrees.

Pull the diff cover and look around, atleast change fluid which appears contaminated.

C-Clip rear ends have a bit of play in them in/out at the wheel side - more as the cross pin wears.

Ron

Zuki-Ron said:

Maybe, you should be looking there. Growling when on the gas usually indicates bad pinion bearings or carrier bearings. Check your pinion for play without the drive shaft installed. There should be zero in/out play. Rotational, a few degrees.

Pull the diff cover and look around, atleast change fluid which appears contaminated.

C-Clip rear ends have a bit of play in them in/out at the wheel side - more as the cross pin wears.

Ron

Click to expand...

Thanks. I'm not going to put any money into this axle, and that's why I haven't dug into it. It doesn't have clips as it's from an 89, so maybe the tire movement means the axle bearings are worn. I'll be installing a 8.25 when I find one locally. I just hope/want to be sure the noise isn't my np231 because after I swap the rear end and do a hack and tap with a new driveshaft I would be pissed if the noise was still there.

You won't be able to sell the internals of the cat - yes, it has platinum group metals in it, but they're on there in almost vanishingly small amounts plated onto the surfaces of the ceramic honeycomb. There are only a few grams of precious metals per catalytic converter.