Grinding Noise

[xjchris98]

Ive recentally been getting a "grinding" noise after accelerating then letting off the gas. It only happens for a second or two, and is periodioc then it goes away. It sounds like its coming from right under me, but Its hard to tell exactly when driving. I've checked all the U-joints and none of them seem to have any play or show any signs of being bad. Transfer case fluid is full and still very clean. I plan on doing the diff fluid this weekend. Heres the specs of my jeep:

2" Rustys AAL, with spacers in front and V8 ZJ coils. I dont have a SYE or transfer case drop, but I never had this noise before, even right after I put the lift on. Any help or suggestions are appreciated.

[90xj06]

is it the tranny?

[xjchris98]

It doesnt sound like a tranny issue, as it seems to come and go and isnt very consistent. Like I said earlier, it kinda seems as thought its a driveline issue, but I really have no clue...

[JEEPINIT]

How many miles? I had to rebuild my front driveshaft at 125k. U joints were ok, but the insides of the double trunion joint were done. Catch it early enough and you can get a kit to do it yourself. You can remove the front shaft and drive it without any problems. this might help you pinpoint or eliminate one possibility.

[xjchris98]

Its a 98 with 87k on the clock :dunno:

[Bainer]

I have the same problem but I recently rebuilt my front drive shaft. I have a 3" lift with out a t-case drop and 211k miles on the clock.

[xjchris98]

If its not something to be concered about...then I wont. I just want to make sure i'm not gonna gernade my transmission/transfer case....etc.

[SpAcMuN]

Reviving an old thread I guess, but this seems to be an issue with my rig as well, if I understand it properly. I'm getting a slight grinding noise while in motion, at just about any speed (in 2wd... havent tested 4wd), most noticeable between 20 and 55mph I'd say. Basically, it happens when I put on the gas slightly from coasting, or let off the gas while accelerating, to coasting.

xjchris98, did you ever figure this one out? I have an '01 automatic with 4.5" RE lift, Teraflex SYE, custom rear driveshaft and original front driveshaft. Seems the noise is coming from the rear driveline but I can't tell for sure. It almost sounds like there is play in the driveline or some slack that gets kicked around when torque on the driveline switches directions between acceleration and deceleration in a coast. Any suggestions? I'm concerned that something is wearing out or letting me know that it wants to break...

[darjevon]

Check your transmission mount and/or motor mounts. Chances are its probably time to replace those anyway. I had this prob for a while... i let it get so bad that eventually on accel the fan would chew the radiator. It lasted a while like this but eventually it popped while in San Francisco traffic :flamemad:

[Teellandor]

I have that problem as well. It happens in my 92 (still bone stock) after I flog it on a trip longer than 10 miles. I read somewhere around here to check the torque converter bolts. There's an access plate on the front that well let you turn the flex-plate and get to them.

(I haven't gotten this far yet as it hasn't been above freezing in about a month. Also figured I'd have a look when the RE kit got here and deal with it when it's in the air then.)

[SpAcMuN]

Well I'm curious to hear how it goes for you. My mounts look good, but I could see maybe flex plate related. Tranny mount was replaced not too long ago. I guess I'll just keep digging.

[Teellandor]

So am I. :laugh3: But it'll be a couple weeks, yet. My problem could be the mounts.

Found the original post:
Does it go away under load?

My 1991 XJ did the same thing; I thought I had a bad bearing or something getting ready to let loose on the bottom end of the engine. The knocking went away when I goosed the gas for a quick take-off. (I was mad, and gave it a shot out of frustration.) I pulled the inspection plate on the advice of my brother, and found all of the Torque Converter bolts were finger loose! I pulled them one at a time, cleaned them with a wire wheel, then re-installed them with red locktite.

I hope this is your problem...

:)

[maine96xj]

i had the same problem, turned out to be motor mount, rev the engine up some from the throttle cable and see if the motor pitches either direction, if it does its the motor mount, to check tranny put block of wook between pan and jack, jack up tanny only slightly and see if theres a crack in the rubber between the trans and the crossmember.

[Teellandor]

Not the mounts or converter bolts on mine. I had it on jackstands and had somebody else to help me listen for it. Turned out it was coming from the t-case. I pulled it but haven't had time to crack it open, yet. I'm thinking I need a new chain.

[moparmatt]

Not the mounts or converter bolts on mine. I had it on jackstands and had somebody else to help me listen for it. Turned out it was coming from the t-case. I pulled it but haven't had time to crack it open, yet. I'm thinking I need a new chain.

OH MAN new chain!?!?!?! What were your symptoms like. I am thinking mine is a motormount

Mine symptoms are exactly like his...

I'm getting a slight grinding noise while in motion, at just about any speed (in 2wd... havent tested 4wd), most noticeable between 20 and 55mph I'd say. Basically, it happens when I put on the gas slightly from coasting, or let off the gas while accelerating, to coasting.

Did you find out what your problem was SpAcMuN?

Thanks

[GreenXJ2K]

I Have the same weird noise. When you're moving, try gently moving the transfer case lever forward and backward (1/4") without changing the actual mode, and you should be able to hear something. I had a propeller droning sound a while back. My front DS was all wobbly, removed it and now that grinding noise I hear seems like its coming from my TC. Its possible my bearings are shot, and maybe the screwed up DS took them out......well thats my heep, could possibly be the same deal with yours.

-john

[moparmatt]

I Have the same weird noise. When you're moving, try gently moving the transfer case lever forward and backward (1/4") without changing the actual mode, and you should be able to hear something. I had a propeller droning sound a while back. My front DS was all wobbly, removed it and now that grinding noise I hear seems like its coming from my TC. Its possible my bearings are shot, and maybe the screwed up DS took them out......well thats my heep, could possibly be the same deal with yours.

-john

From what I have read your front DS can be wobbly a bit (2WD) BUT ONCE IN 4HI IT SHOULD BE SOLID.

How long has your front DS been out?

[Teellandor]

Mine made no noise with motor under load. When I let off it would come back. Also had to be warmed up (i.e. flogged). There wasn't any kind of vibration, either. I dunno. The case is already out and I'm not looking foreward to the $140 chain. (It was a leaker anyway, so I had to do something about that.)

[GreenXJ2K]

From what I have read your front DS can be wobbly a bit (2WD) BUT ONCE IN 4HI IT SHOULD BE SOLID.

How long has your front DS been out?

The front DS was noticeably bad, I jacked up one wheel, and rotated it to test it, even with the tire on the ground the slip shaft was very loose. Oh and its been out for about a year, I only put it back in when it snows......i'm lazy and cheap, and the last time I took it off-roading I went somewhere no one should have been (bone stock) and it cost me $1000 and 4 hours to get dragged out.


Since you got the case out, I'd recommend changing the bearings, and possibly the teflon(?) pads on the mode fork, hell just do a rebuild. There are rebuild kits that include everything you need. I still get considerable grinding noise on take-off, and jiggling the TC handle makes it worse or better. A lot of my buddies have jeep cherokees, so that helps out for comparison. I say bad bearings.

-john

[Teellandor]

Well, I'm trying to make a chapter run in a month, and thanks to the IRS I won't be able to do much more than just the chain. When I gat back to my normal operating budget, I'll just be looking for a used 231 anyway. (and rebuild that one)

[4x4 Station Wagon]

Ofcourse every situation is different however i to had a grinding or a whirring sound coming from what appeared to be my rearend 8.25 cor. I jacked up the rearend placed it on stands and threw it in gear to try and determing the location. I would have swore it was my wheel bearings so i replaced them. My ring and pinion looked great while i was in there so done deal right. NOPE still there. I tore it back apart and found to have the ring gear side carrier bearing looking like &%^ along with the small pinion bearing slightly bad. I ordered a full bearing set with shipping from Randy's Ring and Pinion for 95 or so and threw it in done deal. Hope this helps