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weird noise

SINCITY192

NAXJA Forum User
Location
Bronx, NY
88 xj 4.0 6cyl auto trans...
I was driving from work like always and when i came to a stop (not sudden) but nice and easily... as im idling at the light I here what sounds like vibes so heavy it sought of sounds like something metal hitting something.... it really is so hard to explain... but i really was wondering if my jeep was about to fall apart right then and there.... but as i got onto the gas the problen just goes away... I cant even seem to get it to do it again it doesn't happen in park. Im just not sure what it could be my tranny lines arent fully metal its mostly hose going to the rad.. so i dont think its that banging anything but it something and Its not the 1st time I have heard this..... I've triend while in drive and at a light opening my door and sought of just looking under the car still sitting down because i need to hold the brake of course but i cant see a thing like that......
Im just wondering if anyone has had something like this happen
 
My '90 does this, It may be the exhaust touching the cross memeber. I'm still troubleshooting this myself. If it's the same noise as mine (sounds like it is) I wouldn't be too concerned about it however, it is still something that needs to be found
 
Generally it is the exhaust on a crossmember. I would check you motor and exhaust mounts. I worn trans mount may also cause that issue. Have a friend you trust put your Jeep in gear and crawl under with some decent gloves on and try to move the exhaust to see if the issue goes away.
 
My jeep did it.. it was the exhaust mount off of the trans mount hitting the exhaust.. I do have an aftermarket exhaust so it was not mounted to the mount. Idk if you have the exhaust mounted in the stock location or not but like jeep man said get under there and see if you can move the exhaust.. use gloves or while its idling take for foot with a shoe on and see if it wiggles around enough to hit the cross member or anything else.. for me, the fix was to remove the tranny cross member, then remove the trans mount and mount attatched to the trand mount.. a cut off wheel took it off and my sound went away!
 
ok since you guys mentioned it i did once have this noise and i change the tranny mount and it went away.... well just recently i drop the tank to change the pump and the metal bracket that the back of the exhaust connects to was held on by 2 bolts...
its the bolts that hold on the gas tank skid plate well i ended up doing so serious pulling and pounding and cutting to remove a stripped bolt.. since it was stripped on the threads i could only get it out so much.... then i was forced to cut it off with a grinder.... point being I no longer am able to attach the muffler bracket because of that bolt. I thought to just hold it up by one but the metal piece that the bolt screws into moved and its too hard to get it to line up with the hole and screw that bolt back in,... so I decided to eliminate that skid blate and bolts so only thing thats hollding the muffer up there is a wire coat hanger i willing to bet this is my issue only thing is can vibes in the back be felt in the front? i got the next 3 days off i wanna figure these little problems out asap.

Thanks 4 all the help guys
 
88 xj 4.0 6cyl auto trans...
I was driving from work like always and when i came to a stop (not sudden) but nice and easily... as im idling at the light I here what sounds like vibes so heavy it sought of sounds like something metal hitting something.... it really is so hard to explain... but i really was wondering if my jeep was about to fall apart right then and there.... but as i got onto the gas the problen just goes away... I cant even seem to get it to do it again it doesn't happen in park. Im just not sure what it could be my tranny lines arent fully metal its mostly hose going to the rad.. so i dont think its that banging anything but it something and Its not the 1st time I have heard this..... I've triend while in drive and at a light opening my door and sought of just looking under the car still sitting down because i need to hold the brake of course but i cant see a thing like that......
Im just wondering if anyone has had something like this happen

While this may not be your problem it does make a sound such as you described....
Remove the inspection cover from the bottom of the transmission bell housing and inspect the torque converter bolts for tightness.
These are the bolts that attach the torque converter to the flexplate.
The bolts loosening up over time is a common problem.
If you find them loose; remove one bolt at a time and apply blue loctite and then snug them down. IIRC the torque spec of the bolts is 25 ft/lbs.

Charles
 
While this may not be your problem it does make a sound such as you described....
Remove the inspection cover from the bottom of the transmission bell housing and inspect the torque converter bolts for tightness.
These are the bolts that attach the torque converter to the flexplate.
The bolts loosening up over time is a common problem.
If you find them loose; remove one bolt at a time and apply blue loctite and then snug them down. IIRC the torque spec of the bolts is 25 ft/lbs.

Charles

hey charles would u have a picture of it!!! I will search in the meantime. I think the bell housing is the area where I attach the CPS right? just wanna be sure!! thanks again
 
based on your description of your "halfassed" exhaust hanger set-up, I'd correct that before I went on a goose chase for other causes. The exhaust is supposed to be held by a semi-solid mount at the trans cross member, a flexible rubber doughnut mount just aft of the muffler, and a thick nylon strand reinforced rubber strap next to the fuel tank. If any of these are damaged, broken, or replaced with coat hangers, you will get the symptom you have described.

Your goal should be to achieve a solid exhaust that cannot be manipulated more that 1/4" by hand at the tail pipe and 3/8"-1/2" clearance form any part of the chassis or body.

...and yes, the exhaust rattling at the rear can be felt toward the front as it's a solid tube all the way to the engine. It will transmit the vibration from one end to the other easily.
 
based on your description of your "halfassed" exhaust hanger set-up, I'd correct that before I went on a goose chase for other causes. The exhaust is supposed to be held by a semi-solid mount at the trans cross member, a flexible rubber doughnut mount just aft of the muffler, and a thick nylon strand reinforced rubber strap next to the fuel tank. If any of these are damaged, broken, or replaced with coat hangers, you will get the symptom you have described.

Your goal should be to achieve a solid exhaust that cannot be manipulated more that 1/4" by hand at the tail pipe and 3/8"-1/2" clearance form any part of the chassis or body.

...and yes, the exhaust rattling at the rear can be felt toward the front as it's a solid tube all the way to the engine. It will transmit the vibration from one end to the other easily.


Loose torque converter bolts are a known problem on XJs which wont take much time to verify if there is a problem or not....

To answer the OP question to me... The inspection plate is a crescent shaped silver cover held on with several small bolts at the bottom of the bellhousing that allows you to inspect the tc bolts.
 
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sounds like a go getter!!!!! Ill find my bendable magnet and see if i can get the piece that the bolt is suppose to line up with to go back to its hole and see if i caqn get the bracket back on some way! if not ill have to get a muffler shop to weld it!!!!
 
My post is a valid one....
Loose torque converter bolts is a known problem on XJs which wont take much time to verify if there is a problem or not....

To answer the OP question to me... The inspection plate is a crescent shaped silver cover held on with several small bolts at the bottom of the bellhousing that allows you to inspect the tc bolts.

no argument with it's validity and always a good idea to check EVERYTHING that can cause a vibration or noise when one's noted.
 
@ charles after i fix my muffler I'll check the flex flate too just for experience!! thanks guys i'm going out front to start.
I'll post up what i did!
 
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