Grinding noise in 4H and/or locking in hubs

Hi! I'm a new member but have lurked here from time to time

I have a 1999 V6 Tacoma, Auto, manual locking hubs. I live in north Texas so I almost never use the 4x4 but I have used it, from time to time, only on ice or snow and its work fine when used.

So we had a little sleet last week and I thought it would be a good opportunity to exercise the 4x4. I locked the Hubs (manual) and began to drive, still in 2H, and I could "feel" and hear a kinda low rumble grinding noise. I only drove about 20 feet. I stopped and moved into 4H and drove a few more feet with the same issue. so I unlocked the hubs and back to 2h and all was normal. for trouble shooting I left the hubs unlocked and engaged 4H and the grinding came back. then back to 2H with no problems.

I did recently put bigger tires on the truck. all 4 new tires and all the same size could this be the issue?
I checked and changed the transfer case fluid with no change. The fluid looked used but no metal shavings

any help or input would be greatly appreciated

 

Check for slop in your cv axles where they go into the front diff, also inspect the u joints on the front driveshaft

 

Like the poster above me suggested, check your axles.

When locking your hubs, even if you're in 2wd, you've engaged the axles and so now they're spinning with your wheels.

 

thanks for the input! I'm fairly mechanically inclined but I'll need some input on how to check those.

I should mention that when the hubs are locked and/or 4H these is a noticeable drag. almost like something is binding.

 

If you read what you typed to us, you'll see that you've already pointed yourself in the direction you need to go as far as what to look at and diagnose.

You engaged the hubs, meaning you turned them to LOCK, and experienced a grinding noise.

At this point now, your axles are turning with your wheels.

 

You did the right diagnostics which points to any drive-line elements: axles, front diff, driveshaft and t-case. Engaged from either end something is grinding when turning (not even under load). Could be anything of these four. How to pinpoint which one is doing it? I don't know the best or easiest way but maybe disconnecting the driveshaft and repeat the test will show et least which end is grinding: diff or t-case.

 

The first thing you need to do is get under the truck and look for any noticeable leaks coming from the front diff area.

Something else I would suggest is jacking the front of the truck up, lock the hubs and spin the wheels. That might narrow down where your problem is

 

Good point. I would do this.
It sounds like it's either the front diff or transfer case. Jack it up and mess with the settings and spin things.
Transfer case in neutral, hub locked and spin the wheel by hand. Are you hearing something in the diff? I think this combination will be easy to spin by hand and isolates the front diff. Maybe you wont be at enough speed/load to hear the noise, but maybe you will. Pretty easy.

 

So what did you find out?