This problem just cropped up a week ago and has defied my limited troubleshooting knowledge thus far. Here's the problem:

When I accelerate from under 5mph at a decent rate (e.g. not grandma slow or psycho fast) what sounds like a rattle comes from the underside center of my truck. I've checked the mounts for my exhaust and everthing seems to be tightened down. There is no wobble in either the transmission or xfer case shifter and it doesn't happen when I accelerate slowly or stomp on the gas.

I haven't lubed the driveshaft for a while, but wouldn't that cause a shudder?

 

theres only like a million exahust sheilds on that truck any number of which could have started to come loose and rattle at a weird frequency

 

I had a little pebble stuck between my catalytic converter and its heat shield. It would only rattle on occasion, but it was driving me crazy. I took a flashlight and my creeper out and went over every inch of the exhaust system. I didn't find anything wrong, so I started my search over again. On the second pass, I found the pebble. After removing it, the rattle was gone.

 

Does this happen at all times? Does it happen when the truck is either warm or cold (or the weather ousdie it cold (San Diego cold, even)?

 

My wife's Outback had the same kind of sound. Turned out the "maintenance free" driveshaft had a frozen front U-joint. That was at about 110K mi. HTH.

 

It doesn't appear to have anything to do with the weather. I was thinking it had something to do with the exhaust manifolds too, but if I put it in neutral and rev the engine I can't get it to do it so I'm pretty sure it is something drivetrain related.

It seems that it depends on the load placed on the drivetrain not the RPMs.

 

Does it change with the load/RPMs, or is it constant whenever it does it?

 

It is definitely a constant rattle.

 

TITTT

Scout has an auto tranny and is 4wd in case any of you were wondering.

 

I think I have something really similar. My Runner is a manual and whenever I am accelerating from low RPM's its an annoying rattling noise from what seems like under the engine. I am taking my car into the dealership next week for some other things, I will ask them to look into it.

 

Are you only expieriencing a rattle, or when you reach a certain speed, are you feeling some shaking? If not, I think you might be able to rule out the U-joint possibility.

 

my buddy has a frontier, and his was making a simular noise under acceleration and braking, it turned out to be the collar that shields the drive shaft from the transmission, it was bent from running over a stump or something and made it rattle under those conditions. good luck hope you find it

 

* There is no shaking of the vehicle whatsoever
* it's only an audible rattle as far as I can tell
* the speed at which I'm going seems to have no affect, it's only under moderate acceleration.
* my truck doesn't make that abominable rattling noice at any point while braking.

Tex - Funny you mention about a housing near the driveshaft since I don't have a skid plate for my x-fer case _YET_ but I don't think that tacomas have that sort of a housing. Maybe tacomas do and I just haven't noticed during all the times I've crawled underneath her.

 

Apologies for bumping an old thread, but this one helped me find my problem. I had an intermittent rattle coming from underneath my 02 4Runner, mainly under acceleration. A tap on the exhaust with a rubber hammer identified the source as the heat shield on the catalytic converter. One of the four bolts holding it on had rusted enough that it had come loose and was rattling in place. I wouldn't have found it without the rubber hammer, because the shield itself was not loose.