Diagnose Grinding Noise while under load

Hey guys, I’ve used Tacoma World many times to trouble shoot issues in the past, but I can’t seem to find a solution to this problem.

Right before my truck shifts, it makes a strange grinding sound. It doesn’t make it when I rev the engine in park or neutral, and I can’t hear it when I accelerate SUPER slowly, but it’s most definitely there. I’ve attached the a video of the sound which occurs at second 5 of the clip.



Here’s a list of things I’ve already checked.
- U-joints: nice and tight
- Drive shaft bearing: fairly tight, maybe about 0.5 inches of movement max
- same noise in 4 wheel drive
- greased all the u-joints with a grease port

 

Is the sound rpm specific by any chance? Mine has a vibration/grind right around 1800-1900 rpm and I've been investigating. Thread (for suggestions): https://www.tacomaworld.com/threads/grinding-sound-when-accelerating-uphill-from-a-stop.725523/

I am preparing to pull my driveshaft to inspect/replace u joints and the CB next. Apparently you cannot tell if they are worn until you remove the shaft. I have a couple videos in that thread. Your video sounds a little like my sound.

 

That’s interesting. I just now drove it around some more, and it looks like it has the grinding sound right at 1600 RPM. I’m pretty sure it does it each time I pass 1600 RPM but sometimes it not actually loud enough for me to notice unless I’m really trying to listen to it. It also doesn’t make the sound if I rev the engine at 1600 RPM in neutral or park. Any ideas what it might be?

 

Best lead I have so far for mine is CB/floppy ubolts and apparently you can't tell until you pull the shaft. Changing them out seems simple enough so I'm going to try it soon to see if it fixes the problem. If not I may be trying out a Tom Woods one-piece driveshaft for the rear. Since I don't do much offroading I'm not worried about the 1" clearance.

 

Possibly a cat heat shield rattling. Mine would vibrate at the oddest times and it sounded like the truck was falling apart. Then it gradually got worse and I was able to pin point it. Tightened up the heat shield and the rattle was gone.

 

Also, a simple way to eliminate the driveshaft as a possible source is to put the truck in 4wd, remove the rear driveshaft and go for a drive in front wheel drive. Completely safe to do, I've had to drive 5 hours home on the highway like that before.

 

Ok thanks for the help. I’m a little too busy to deal with it right now, but once I get a chance in a couple weeks, I’ll tighten the heat shields, order new U-Joints, then try the front wheel drive thing before changing the U-Joints

 

heat shield

 

It’s been a little while but I figured I’d update you guys. Turns out the issue was just the shield around the catalytic converter. I bought a large hose clamp for a couple bucks, and now it’s totally quiet.

 

Thanks for coming back with a resolution, that’s always helpful for future readers dealing with the same thing.