2wd to 4wd grinding on engagement

Hello, I have a 2001 SR5 access cab tundra. I live in Alaska and use the 4wd often for snow. All of a sudden I clicked my 4wd button and a terrible grinding sound followed while the 4wd was engaging. Once engaged it worked fine. This sound only happens while moving. Disengaging does not cause any unnatural sounds, even while moving. I never drive in 4wd over 50mph and never engage it going more than 20mph.
I thought the actuator from the t-case could be the problem but I haven't found anyone else with this problem. What is it that synchronizes the front driveshaft and the rear? Thought this could be it but having trouble with the dx. Thank you for the help.

 

At the very least, I’d change out the fluid and look for metal debris to see if it’s serious. I would avoid using it otherwise till you know for sure. That doesn’t sound normal.

 

Welcome. There are lots of posts on the topic here. On the top right corner, click the search bar, click more. Type in concern and select 1st gen Tundra forum and select sort by relevance.

 

Hey there! That grinding noise when you engage 4WD could definitely be an issue with the actuator or something going on in the transfer case. In Alaskan conditions, these parts can wear out faster. I'd suggest giving the transfer case and differential a once-over to make sure everything's lubed up right and checking for any wear on the gears. Good luck with it!

 

Did you ever figure this out? I'm having the exact same issue with my 2006. And I am in Fairbanks.

 

He hasn't signed on for a few months. But just to sanity check:

• Fluids are up-to-date and changed in the front diff, transfer case, rear diff?
• When you changed the fluids, did any of those three show signs of metal flake, so you maybe can interpret which is the source?
• What fluids are you using in all three, both weight, type (synthetic/dino), and brand?
• Did you check actuator(s) for vent tube being intact?

From the NEW OWNER WARNING/HELP THREAD, some debugging stuff, pay attention to the 2nd to last bullet here to watch that video, for actuator verification:

Drivetrains available and other related info (including 4WD debugging):

• You either get a V6 (2 types) or V8 (2UZ-FE). For V6, it was either 3.4 (5VZ-FE) in 2000-2004, widely considered one of Toyota's best V6 engines, or the VVTi-integrated 4.0L (1GR-FE) for 2005-2006. The V8 came in non-VVTi in '00-'04 with 4spd trans, but added VVTi in '05-'06 trucks with a 5spd trans, with extra emissions via secondary air injection pump ("SAIP" / "SAIS") which eventually dies (bypass kit info here, DIY kit here). That extra emissions stuff is one purchase consideration, it's expensive to replace if you're in an emissions-compliant state.
• Teardown videos for all 4 engines HERE if interesting!
• 2WD and 4WD was optional in all models. V8 only came w/automatic trans, V6 had a manual option, maybe interesting. Transmission swapping to add manual ... yes, it's possible, one or two did it, it's a massive pain in the ass and may cost you more than hunting down and buying a V6 manual truck.
• The '05-'06 trucks had a fully sealed transmission, no dipstick. Earlier years have dipsticks. Toyota originally said the sealed transmissions had "lifetime" fluid. Now they recommend flushing every 100k? 80k? I forget, you get the idea. Plenty here are running on original fluid after 200k+ miles. Best advice for service at any mileage: drain/fill a few times to incrementally add/replace fresh fluid. Don't bother with replacing metal filter.
• For our sanity, if you have a 1GT truck, go into your profile here and update your "Vehicle One-Line Description" to give its year, V8 or V6, 2WD or 4WD, and what cab type you have. This saves us from asking and helps us give accurate advice.
• 4WD trucks have ample grease zerks on the driveline and need to be lubed with moly-fortified NLGI 2 grease every 5k-10k miles unless you like clunks/jolts when braking and accelerating. Note the slip yoke's zerk has a special fill process. If you've got no history on your truck, this is one of the first things you'll want to do. 2WD trucks lack grease zerks on the factory driveline.
• If you're 4WD and you want to re-gear, your front gear ratio must match the rear gear ratio, plan to upgrade both.
• Also for 4WD trucks, Toyota recommends logging at least 10 miles per month in 4HI to keep things lubed, actuators firing, etc. Do it. 4WD is expensive to diagnose & fix. In case you don't know, DO NOT turn sharply on pavement in 4HI on a Tundra (Sequoia is AWD/Torsen, so it's OK).
• If you have a LSD (limited slip diff) in the rear, there should be an LSD sticker on the back of your rear diff/pumpkin. If you see one, be careful which product you use to drain/refill. DO NOT use synthetic oil! Search the forum or ask.
• ALWAYS test 4WD before purchase, 4WD parts are expensive. Throw it in 4HI while driving in a straight line to see it engage, all lights go solid, no beeps.
• If you're reading this because your 4WD isn't working and you need help, check THIS REPLY for some helpful troubleshooting steps to take.
• If you want add cruise control to your truck, check out this thread.

 

Last winter I was going about 65 mph on a road when I hit a curve, and the road there suddenly went from dry pavement to very icy. Without thinking, I pushed the button to shift into 4wd. There was an a bzzz-grind noise that lasted about 1 second. Ever since, if I'm rolling and I shift from 2wd to 4wd, I get the same noise. If I'm stopped, or going very very slowly, there is no noise. Seems like something to do with whatever is pushing the truck into 4wd... the noise doesn't sound "thick" enough to be from heavy parts, or deep inside the transfer case. The buzz/grind sounds almost superficial, and sounds like it's just about under the gas pedal. For now, we just don't shift into 4wd unless we're stopped, which is easy enough. But I like my vehicles to be "whole", and would rather fix it. Won't be working on this though until I can figure out that other problem, the no-crank-no-start issue.