This is my first post but I have been browsing the forum for a few years since buying my 4Runner and getting lots of good info. I have a grinding sound that I can't seem to diagnose after reading many threads on the site. The truck is an '87 4Runner with 308k and a refurbished 22re at 290k. Mostly stock but I installed four new shocks, a Zuk mod, new tires, and I recently installed a new clutch master cylinder. Here are some notes on the sound:

• It sounds like a grinding/creaking metal-on-metal that occurs at about 2 times per second.
• It gets faster as the RPMs increase but not by much.
• In addition, I get a loud crunch every 5-10 seconds.
• It doesn't seem influenced by stearing or rough roads.
• I replaced the fluid in my transmission and both differentials but that didn't help.
• I jacked up the front wheels and there is little to no play in them.
• The front driver's side CV boot is split but it has been for a few years.
• I recently greased both drive shafts.
• The drive shaft rotates a little (5-10 degrees).
• I have no problem shifting and 4WD works fine with no additional/reduced noise.
• I used an infrared thermometer and the front wheels were 120 degrees and the back were 100 degrees.

Any ideas? I am ready to bring it in to a shop but I don't trust any around Seattle. Thanks for any help you can offer!

 

Aloud crunch sounds like bad shocks. But a Zuk mode does have shocks right ?

 

i just traded my 84 pickup for a 95 runner has a grinding rattle metal sound to i thought my rear end was getting busted up started thinking about alot of things but then i really checked and looked around the underbody and found that a ujoint was wearing out and the driveshaft started to move far out and started rattling against my fuel tank. might be somethin simple just take an extra look around and take your time

 

Find a long hill and with the motor off and it rolling, that should tell you if it is motor related or drivetrain related. If it motor related, start looking at belts, pulleys, and anything near them.

 

Have you greased the spindle bushings lately?

https://www.yotatech.com/forums/f116...ctures-100327/

 

Just some numbers to help you isolate where it's coming from.
- At 30 mph, the wheels (and axles) turn about 4-5 times/sec
- The drive shaft turns about 16-20 times/sec
- At 2500 rpm, the engine turns a bit over 40 times/sec

 

Thanks everyone. It must be the wheels, axles, or differential. There is no play in the wheels when jacked and no extra noise while turning so I don't think it's the bearings. The truck has manual 4WD so I don't think it has an ADD system. Any other troubleshooting tricks?

 

I just wiggled my drive shaft again and it rotates very slightly and makes a knocking sound in the transfer case. I'm wondering if this means the oil could be low in the transfer case, which could cause this noise.

 

I brought it in to be looked at and the technician thinks it is bad bearings in my rear differential. He used a stethoscope and thinks it is the bearings on the rear driver's side axle. Time to bring it to a differential service...