GW has developed some sort of rattling noise from the engine or trans that I can't id

[DanHS]

A little while ago the Jeep began making this slight rattly noise under acceleration from stoplights when warm. It's hard to tell where the noise is coming from, sounds sort of like from the trans maybe. Recently it has gotten worse, a lot worse, now it makes the noise much louder any time I accelerate from a stop, and the noise doesn't let up until I've stopped accelerating. It doesn't come if I'm accelerating at speed, although sometimes it'll rattle a bit when accelerating from a low speed. Sometimes it will rattle when the truck is stopped in gear, but not neutral, and if stopped in gear and turning the wheel it sometimes rattles a bit. In reverse it will not rattle at all, so it seems to be a transmission issue, unless it's some bearing or something that only rattles when spinning in one direction.

Now the rattle itself sounds sort of like spark knock, but it isn't, I can retard the spark timing to the point that it barely wants to run and it will still make the same exact noise, and again it only does it in drive. It sounds a little more like something spinning and rattling, I thought maybe like loose TC bolts, but the rattle isn't consistent, it comes under load or increase in rpm, and only when in drive. Another description of the sound could be that it's similar to when gears are grinding, like say when trying to shift a 229 into gear if the Jeep was in drive, but with a more loose, rattly sound.

I took a video of driving with the noise, but the sound didn't come out too well. I'll try again and see if I can get a better recording of the sound, so you know exactly what I'm describing.

[tkiller13]

I had a rattle in my 78 chero. See sig. I ended up being an exhaust bracket near the tcase had come loose. It would only rattle on acceleration, once I reached a steady speed it went away. Just an idea check your you exhaust clamps.

[DanHS]

I thought of the exhaust, it's on the way out, when I have a little more money everything after the manifolds is getting trashed for a nice high flow H-pipe and a straight pipe going to a turbo muffler and then out the back, and the pass side manifold needs to be removed again and reinstalled with a copper gasket and new bolts, as the remflex gasket I did earlier broke apart after a year. But yea, it could possibly be something in the exhaust rattling off.

Anyways, I crawled under to look for loose rattly things earlier (didn't examine the exhaust though), and saw this:


The mount for the trans that handles the added torsional torque load is coming apart, the bushing is split and spitting out, that could easily explain the rattle and vibration I can feel under load, and when in reverse, the force is twisting the trans the other way, so it doesn't rattle without the load on it. This theory seems like a good place to start.

[grand_wag_85]

I was going to recommend the torque thrust stopper thingy but I see you have already found it

[talntar]

just hope it's not a bad thrust bearing

[710 Burner]

The exhaust is usually in some very tight spaces, so I am betting that you are hearing the pipe rattle when you torque up on that bad mount. I had a cheapy turbo muffler that had pressed in pipe flanges on it. After a period of time the vibrations caused the press fit to work loose enough to let the pipe spin. The pipe twisted into a position where it was touching the frame and would vibrate even at idle, which drew my immediate attention.

[cmelo]

I had worn out tranny mounts like yours and developed a rattle. Didn't have time to change out the mounts before an offroading trip and went anyway. On the way home I heard the rattle and it got louder and louder. Turns out it was a cracked flexplate and it eventually sheared right off from the "spokes". Lesson learned change your worn tranny mounts ASAP. If the little torque donut things are worn out that bad I would go ahead and change the tranny mount to while it's apart, you wont regret it.

[Chris P.]

just hope it's not a bad thrust bearing

X2

My '74 had this problem. It sounds exactly like what you describe.

[temps425]

I have the same symptom except it only happens in Drive...never in P or N. Did you ever diagnose this issue? I'm going to get under w/ a stethoscope today. Whats the safest way to lay under a wag in drive jacked up from the front? I need a ramp...

[DanHS]

Blocks under the tires and on either side of them, to keep it from dropping or rolling. Though it's tall enough you should be able to squeeze under the truck without jacking it up. I never really did figure out the problem, it kinda went away when my exhaust got knocked apart, but it did it a little for a moment after accelerating hard whilst turning sharply. I'm still unsure if it was the mounts or the exhaust or what, but another suspect is something in the t-case breaking, since my 4wd doesn't engage now.

[CJ5]

I had a rattle, more of a tick coming from the same area in my Suburban. It turned out to be flywheel/flexplate bolt had back its self out because of a crack. These flywheels are much stronger than in a new Suburban but something I will throw out there.

[jaber]

I dont know how the 229 acts, but what you described is exactly the way my QT acted when the chain started slipping. It was a "pop, pop, pop" on acceleration.
I hope yours is not this bad....

[trellis8]

I had a rattle, more of a tick coming from the same area in my Suburban. It turned out to be flywheel/flexplate bolt had back its self out because of a crack. These flywheels are much stronger than in a new Suburban but something I will throw out there.

Had the same problem on a '90 3/4 Chevy plow truck last year until the flywheel came apart.

[temps425]

Blocks under the tires and on either side of them, to keep it from dropping or rolling. Though it's tall enough you should be able to squeeze under the truck without jacking it up. I never really did figure out the problem, it kinda went away when my exhaust got knocked apart, but it did it a little for a moment after accelerating hard whilst turning sharply. I'm still unsure if it was the mounts or the exhaust or what, but another suspect is something in the t-case breaking, since my 4wd doesn't engage now.

Yah I can get it to do it when cold and in drive, not moving...put my head down there, cannot tell for sure where its at, may be from t-case. It sort of sound like gears grinding, but it sounds more tinny and high pitched than the sound of a transfercase going half into gear. No idea how to diagnose the problem...

[DanHS]

I would be looking to the flywheel and transfer case. On my GW, I'm wondering now if something got jammed in such a way that the mode shift fork was engaging slightly, causing something to grind in the t-case and jam up, not sure as I don't really know just how everything functions in the 229, and I haven't opened it up. I need to get another 229, then I can take apart this one and figure out what it is.