90 XJ auto transmission help!

Hi, In the last few weeks our 90 XJ (4.0 automatic np231) has started making a rattling like noise,it sounds like its from the front of the transmission bellhousing. I sidelined her jeep until I got a chance to look at it. Today I removed the cover and checked the torque converted bolts, one was loose. Put it all back together and the sound was still there.
When we start, a little bit of gas and the noise it there. Then gets less as the speed gets higher and is not noticeable around 40 mph..


The transfer case had plenty of oil, perhaps in need of change.
the transmission’s oil is full and the color looks great.
The sound does not happen if the Jeep is in natural or park.
Same with the transfer case in natural and the transmission in drive.
The engine sounds great and runs strong.
It drives and shifts fine, except for the sound.

For awhile it seemed like the sound was intermittent, every time I tried to track it down it wouldn’t be there
If the start out is slow the sound doesn't always appear. But now in regular driving, like pulling out in to traffic the sound is there.
Any help would be appreciated.

Could be a cracked flexplate. Need to pull the trans and have a look.

JXPEEJ said:

Could be a cracked flexplate. Need to pull the trans and have a look.

Click to expand...

I didn't notice any cracks when turning it. Would a cracked flexplate cause the symptoms?
PS
Pulling the tans, is it a one or two person job?

Cracked flexplate could cause the noise you hear. Pull the cover again, get a bright light so you can see around the bolts , use a pry bar( carefully) and pry the flexplate, look for cracks. Very common.

Sometimes you can not see the cracks until you pull the trans. Most of the
cracked flexplates I see are cracked around the crank bolts.
Pulling the trans is a one person job but if you are doing this for the first
time make it a two person job.

JXPEEJ said:

Sometimes you can not see the cracks until you pull the trans. Most of the
cracked flexplates I see are cracked around the crank bolts.
Pulling the trans is a one person job but if you are doing this for the first
time make it a two person job.

Click to expand...

The ones I've seen cracked are pretty badly cracked before they exhibit the sounds you are hearing.
Easier to do with two people, a lift and a tranny jack. If it is cracked then replace it don't try to weld it.

Thanks for all the advice. We finally found the problem.
Long story short; We pulled the Transmission back in July, couldn't find anything wrong. Flexplate looked fine, I wondered about the torque converter, but still didn't see anything wrong.
The poor Jeep was set to the side until we could afford to take it to a shop.
It went in 3 weeks ago, the diagnosis was a combination of engine mounts (which I knew were bad and had planned to replace later, but she gave them the go ahead anyway) and worn out U-joints on the drive shaft.

Drive shaft u-joints were not on my list of things to check, and if I had kept at it I'd never found them until dead last. I violated my own DIY ethic by taking it to a shop thinking it was a transmission related problem. Oh well, live an learn.

For anyone else investigating a similar problem, it's probably worth giving the U-joints the once over.
I doubted they were the cause at first, but the proof is in the driving and the sound is gone!

I have a question about this.

I have a 2000 cherokee classic with the AW4.
I am getting a sound when my transmission is in Drive and my vehicle is at a stop. It is only made at a full stop or just in gear with no power.

The sound is a rattling or knocking, it sounds like it is coming from right underneath the shifter. It kind of sounds like the sound is rotational, meaning it is happening because of something spinning. But i don't know if there is anything within the transmission that would rotate at a full stop in drive, and i don't think the driveshafts spin while at a stop. If i am wrong i would love to know.

My thoughts are:
Flexplate
Torque Converter
Motor Mounts - Although i have had bad motor mounts before and the experience i had was that these only bothered me when i took off or went over a bump. These things are not currently happening.
U-Joints - It could be this but the driveshafts don't move a whole lot if i try to shake them.

Any thoughts or advice would be very uch appreciated.
Thank you.

PBEn

I would automatically inspect the flexplate. Its common on XJ's although I don't hear about it as much on later models.