Fluid Changed - 4WD Noise

Long time lurker, first time posting. This community has helped me a lot in the past, but after extensive research, I cant seem to identify the issue with my 4WD.

I have a 2010 long bed Tundra 4x4, towing package, 4.6L engine with 117k on the dash.

Yesterday, I swapped my transfer case and front/rear diff fluid with Lucas

$39 75w-90 GL-5 Limited Slip, Ultra Long Drain 500k Miles, Manual Transmission, Gear/Differential Lubricant (1 Gallon)

75w-90 full synthetic oil. The rear diff fluid was slightly brown, transfer case fluid was near new looking and the front diff fluid was pretty dark with possible metallic filings (could have been my dirty drain pan).

Anyway, after swapping the fluid and taking it for a test ride, everything seemed fine except for 4WD. Now when accelerating in 4WD, I hear a growling/rattle noise coming from the front end. About an hour ago I added some friction modifier to both diffs and the transfer case with little to no change in the sound. The noise only occurs while accelerating in 4WD, 2WD is quiet. I also lubed my drive shafts u-joints, no change.

I have read that I may need to either add more posi trac additive or swap out the fluid with OEM oil.

Anyone have experience with these issues, any advice? I would hate to dump 100$ in oil but I would rather do that than pay several grand for a new diff/ transfer case. I dont have a truck lift, so Im not sure exactly where the noise is coming from, but I assume it is either the transfer case or the front diff, since those were the only areas I serviced.

What should be my next move? Stealership? New oil? More additive? Sell the truck? (Lol)

 

I would definitely double check levels before doing anything else. Also be sure any hardware you loosened up is tight, as you could just be hearing something rattling around.

 

Double checked all my levels when I added the posi trac friction modifier today. Wasnt able to get much in because everything was full. I did take off one skid plate on the bottom of the transfer case yesterday, I will double check that plate and report back. Thank you!

 

Transfer case skit plate is on tight. Was hoping that was it!

Noise sounds like a rattling roar more than metal clanging

 

The common roar that people hear coming from the front of a Tundra is usually the needle bearing failing where the front left CV axle connects to the front diff. Unfortunately, this noise is usually loud in 2WD and goes away in 4WD, which is the opposite of what you reported.

 

I had loud noise and vibration when accelerating in 4wd on my ‘08. Turns out I had a corroded out and broken front diff mount bolt that allowed the driveshaft yoke to rub the crossmember when the torque tipped the rear of the diff down.

 

The way you describe your noise is almost identical to what I am experiencing. I have a 5 inch lift with modified front diff mounts so I will check this out next. Likely wont be able to get the skid plate off until next weekend, so I will update this thread later this week. Thank you!

 

No problem, hope it’s that easy for you too.

I would describe the noise I had as “ratcheting”, it was pretty loud and the vibration through the floorboards was significant. I thought it was a cracked side gear in the front diff causing the spline to the axle shaft to slip, or something along those lines. Took a while to track it down, and I fix broken mechanical stuff to put food on my table.

There is no need for LSD / positrac friction modifier additive on an unmodified ‘07+ Tundra either, as there are no factory installed mechanical limited slip diffs. It also won’t hurt anything now that the additive is there.

 

I hope its that simple as well. The noise and rattle is pretty subtle and I cant hear it above the wind at speeds over 40 mph. But Ive always been taught that your truck will tell you (via noise and vibration) before something fails. Id be willing to bet one of my drop bracket bolts is the culprit.

Guess its a good thing I spilled most of the posi trac in my drain pan. LOL

 

Just want to follow up and tell you, it was in fact the drivers side differential bolt that was stripped! Apparently the bolt hardware I used to drop the differential was not of the highest quality lol. Was a torture pulling out the stripped bolt and nut, but I eventually got it removed and replaced with a set of stainless steel bolt/washers/nut. Sounds perfect now. Thank you for pointing this out to me!

 

Good stuff.

 

Damn.

Good to get that out of there and replaced with more proper units.

Always appreciated when the conclusion is posted!