Vibration and intermittent rattling while at full stop

Have a 4 banger ( 2003 ) Toyota Tacoma ( lifted ) 4 x 4 with 160,000 miles did the same thing for years and went through all the usual stuf of TRY TO FIND OUT WHY THE VIBRATION --------------- soooooooooo one day I put in a full tank of PUREGAS with no ETOH !!!!!!!!!!!! I could not believe the difference it made !!!!!!!!!!! no shakes, no vibration !!!! It now runs better than it ever has !!!!!!!!!!! I don't think these trucks were designed to run off gas with ETOH. ANYWAY try it you might be very pleasnatly surprised !!!!!!!!!!!!!!!!!!!!!!

 

Was hand washing my 2006 DC 4x4 and noticed that the screws/plugs under both front fenders at the bottom were missing. These are the screws/plugs that mate the inner plastic fender well liner to the actual fender. Will be going to Toyota tomorrow for replacements..........will post results as soon as installed.

Looks like there is just enough play for the liners to rattle around and may be causing my mystery noise.

 

I am not positive, but I have almost concluded my noise is just normal vibration/resonance noise from the engine and exhaust pipe. I only hear it faintly at idle rpms. Maybe a sign that the engine is finally broken in at 80K+ miles.

 

I had this same issue that started after I took my Tacoma to the dealership to have a new timing belt, water pump, idler pulley, thermostat, and drive belts replaced.

When I bought the truck back in 09, It had noise coming from the alternator pulley from where the dealership degreased the engine compartment a bit too much, but I just kept it lubricated and it lasted 5 years with no problems. Each oil change, i just shot it with a little WD40, and it shut up.

After I got the timing belt and all done, I decided to just go ahead and get the new alternator. The mechanic at toyota tightened the belts a lot more than what I thought was normal, but no matter what I did, at this point the noise wouldn't go away, so I attributed it to the initial pulley issue from 2009.

I got 5 alternators and it STILL makes the noise. I tried ones that toyota ordered, i got 3 from CarQuest, 2 of which were from a reman factory called BBB, and today I got a Denso, and all of them are making the noise. The noise is rattling intermittently so bad that if you're standing around the bed, you can hear the exhaust rattle, but it's definitely the alternator.

I:
-took off all the belts, started it up, and 0 noise. (which eliminated the possibility of it being the new water pump.)
-put on just the AC belt. 0 noise.
-put on just the power steering belt. 0 noise.
-put on both. 0 noise.
-put on just the alternator belt. Noise came back.

I tried putting on just the alternator and one of the other belts to see if maybe it was more tension in one or other direction and causing the fan clutch to be out of balance, which might cause a vibration or noise, but it still rattled.

I called toyota and talked to the mechanic there. He said he's worked there for 12 years, and this is a common issue with the remanufactured alternators. He said they almost never replace the rear bearing on the alternators.

He even took a 3 foot long prybar and touched one end to the alternator when the truck was on and let me put my ear to it, and you can hear it whining like a 2 year old brat.

The only thing at this point that I know to do, is to try and find a Alternator Decoupler pulley that will absorb the vibration so it doesn't rattle anything else loose over time.

 

I found out what was rattling . Its the exhaust shield over the pipes towards the front . They were lose so I drilled some self tapping screws in them and I haven't heard a the noise since. Its been over a yr now.

 

It could be it is your throw-out bearing. I had to replace mine on my '08 TRD at 48K. Clutch and pressure plate as well. I now have 105k and it is doing the same thing. It was all replaced on warranty by Charlesglen the first time but I am probably on the hook this time.
I don't drive it had and hardly any real 4X4 stuff.
Mileage quoted in kms.

 

Turns out it was all of the alternators I was getting. I installed a total of 7 (S E V E N) Alternators before I finally got a 100% NEW one from Carquest.

The first 2 were from the Toyota dealership, then I got 3 from carquest, then carquest upgraded to a Denso, which was the worst of the 7. The Denso was louder and it also backfed through the radio speakers.

What's happening is the remanufactured alternators arent getting the bearings replaced like they should. If you put a long screwdriver, or a long extension to the alternator, then put your ear to it, you can hear the grinding. It was bad enough to rattle my shifter and even the bed of my truck.

 

Rattle noise - exhaust shield over the pipes toward the front/ they are loose so drill some self tapping screws in them

 

Rather revive then start a new thread.
I might be in the same boat as you, when I come to a stop my RPMs dip from 600 to around 450, then usually will bump up from the AC kicking in. But sometimes they just hover below 500 around 450 like I said and it feels like the trucks going to stall if it goes any lower and some things make noise since it's rattling a bit. Did you ever end up pin pointing your issue?

 

Sounds like I'm not the only one with this issue. My '05 4 cyl starting doing this after a battery and alternator replacement last weekend. The ECU got reset when the battery was replaced, but I didn't notice the issue until a few days later when the alternator got replaced. Ever since then though if I'm at idle long enough when the engine is warm it starts doing it. My truck is a stick shift, so I'm not going to have the same transmission symptoms that ALBtacoma was having, but the fluctuating RPMs and almost stalling sounds like what BCWcrüe and ALBtacoma were seeing.

I stopped by Autozone yesterday on my way to work yesterday to get a new air filter (dirty, but not the culprit) and some fuel system cleaner and they took their OBD reader out and looked for likely culprits. Voltages looked good, there were no codes and the engine wasn't misfiring or anything, and nothing else obvious. From everything I've read it sounds like the throttle body might be the culprit, but I really have no idea. I'll definitely post again once I get to the bottom of it though.