Mystery Noise

I know these type of issues are practically impossible to diagnose in print, but I'm hoping there's maybe someone out there who's had this happen...
The best way I can describe it is a clicking or rattling upon acceleration - most noticably within the first 10 or 15 minutes of drive time. Also if it's been sitting at a long stoplight. I've pretty much narrowed it down to drivetrain issues, but could it have anything to do with a power steering leak? One of my PS lines needs to be replaced this weekend, but the clicking/rattling is not consistent in timing or frequency. It also happens as much going in a straight line as it does when I turn. I checked the tranny fluid level, and it was normal. Have not had time to pull the wheels off, but the u-joints appear to be okay. No visible loss of tranny fluid anywhere underneath. Haven't checked the t-case, but I just drained & filled it 3 weeks ago. At fist I thought it was something on my suspension rattling or maybe my disco cables slapping around because the noise is so erratic.
Any ideas?

My first thought was to check to see if any part of the exhaust pipe, muffler, or cat is vibrating against something, especially near the hangers, but as I read more of your post this sounds doubtful. Still worth a look. Sometimes these ticks, rattles, and clicking noises can be a pain to diagnose. If you can duplicate the noise at very slow speeds, try having a friend walk along side as you drive it. This might help you narrow the problem to a more specific area like the engine area, tranny area, rear, etc. Have you checked the front and rear drive shaft U-joints? The only other thing I could offer at this time is to make sure everything from one end to the other is tight. Also check the heat shield at the intake manifold. Good luck.

Thanks for the input!
I have checked the exhaust clamps, but not the driveshaft u joints.
Good idea on the heat shield. I didn't think of that one. Could be a possible suspect, as it sounds to be somewhere low on the drivetrain.
I would think that if it were a tranny issue it would be consistent all the time, but maybe not.

Today it seems to make a single clank when I shift from Reverse to Drive.
Definitely coming from somewhere on the front portion of the drivetrain.
Hopefully I can get under it tonight & do some more detective work.

the single clank is either backlash at the rear pinion, or the U-joint right there. Fairly common. But that sounds different than your rattle after a stoplight.
For that i would listen closer if it starts slow, then speeds up as you do, if it continues at speed, if it continues if you shift to Neutral coasting, etc..
Can you make it happen if yopu are in N or P?

I have a subtle rattle coming from the center consul area...buy the transmission (aw4) and transfer case (231) levers. It rattles only on acceleration and it's very inconsistent. Sometimes it even does it when I go from park to drive.

I just figured it was the transfer case shifter linkage. Some guys have had noise coming from worn bushings in the lever. Maybe that's what could be going on. I haven't actually crawled underneath to take a look at it because it doesn't bother me yet, even though it's been getting more and more frequent for the past week or so.

Just hearsay from a stick shifter here, but I think some people have had mystery clanks and noises from a loose flexplate. Might not be a bad idea to take the bottom cover off and check the bolts that hold it on.

Could be a bearing or chain in the tcase is going out. Twist the front output back and forth quickly, does the chain slap?

All good ideas.
Thanks so much to everyone for the info - I really appreciate it!
Hopefully I will have time to check it out over the weekend.
Busy time though - (relatives graduations, etc.) so I may have to park her until I can really give her a thorough shake down.
If it is the timing chain or something like that, I would really hate to hose it up by continuing to drive it!

I second the flexplate bolts if it's an auto. It's very common for them to come loose, and when they do they can sound like you describe. Not too hard to remove that inspection cover and just check. Put some blue loc-tite on them and torque them down if you do find that they're loose. I forget the torque specs, but any decent manual should have them.

I go with the flexplate too.....very common on these for bolts to back off or for flexplate to crack around bolt area, remove inspection cover and check the bolts, also use something so you can pry the flexpalte forward or back(gently) and look for cracks.

After a little more inspection and driving today, it appears that I have a tranny leak somewhere. At first I thought it was a leak in one of my power steering lines. Just a couple of drops on the driveway, but the steering box is covered in fluid. After getting a closer look at the color of the fluid, it is more red than PS fluid should be. The leak appears to be concentrated around the PS area, but there is also quite a bit of fluid on the lower radiator hose. I just replaced the radiator last week, but maybe I'll have to pull it in order to figure out the source of the leak.
Also, on the way to work this morning I have noticed a clank in 1-2 gear (which would explain why I only hear noises at low speed). The clank is more prominent when I am coasting & then apply the throttle.
It's possible that I have several problems going on at the same time.
I mean, it is a '92 with 140K miles (bought it last year w/121K on it) and I did put her through the paces on our most recent wheeling trip. Probably pushed her harder than I ever have before.

I guess the only thing that puzzles me is that if it is leaking tranny fluid, why would it be concentrated on the driver side?
Aren't the lines & fittings for the tranny cooler on the passenger side?
Maybe it's time to bite the bullet & take her to the local transmission specialist...

Spidey said:

I guess the only thing that puzzles me is that if it is leaking tranny fluid, why would it be concentrated on the driver side?
Aren't the lines & fittings for the tranny cooler on the passenger side?
Maybe it's time to bite the bullet & take her to the local transmission specialist...

Click to expand...

The lines come up the passenger side and cross over to the heat exchanger which is on the driver's side. I'm guessing that a line is damaged or not tightened properly after the radiator job. Sometimes the quick-disconnects will leak after they've been used once. Or perhaps the fitting that taps into the heat exchanger didn't get threaded in cleanly. That would put fluid just about where you're finding it.

Not being able to hear it, I'm thinking preignition (ping). Are you seeing a high idle from time to time? Does you heater only blow in the defrost vents. I say all of this since a vacuum leak will cause ping and those are symptoms of a vacuum leak as well.

I have also this ratling noise when accelerating. I noticed that when I hold my hand on transfercase lever the noice doesn't appear. Bushings I assume?