4lo lock in noise

I have a 2012 tacoma regular cab auto 4wd. I went to lock in 4lo and it made a weird grind then clunk and went into 4 low. It did the same thing coming out of 4lo back into 4hi. I was sitting still and in neutral with wheel straight. It has only done it one time. After it done it and I went back into 2 hi it would not go into 4hi unless I shut the truck off and let it sit for a minute. I think I am being paranoid over everything not being properly aligned. I have 150,000 miles on it and have had it since 100,000. I have changed the transfer case oil and diff oil twice since 100,000. I know that's over doing it but would rather over do it the go to long. Has anyone else experienced this problem?

It goes in and out of 4 hi with no issues and no abnormal noises. I just tried it today and it done the same weird noise again today. I think I'm just paranoid.

 

Getting into, and out of low range can sometimes be difficult. Sometimes a slight clunk as it engages/disengages isn't unusual but doesn't always happen. You shouldn't have to turn the engine off.

If you've driven very far in low range the gears sometimes bind up and don't want to disengage. It is helpful to put the truck in reverse and back up 10-15', then pull forward and try again. Repeat until it disengages, and it may take a few tries.

It is also helpful of the truck is NOT at a dead stop. I think it needs to be under 3 mph. I find it best to stop on a slight incline, go to neutral, and let off on the brake and let the truck roll slowly as I make the shift into low range. There is about 50/50 odds that the gears are not properly aligned if you're at a dead stop and they won't engage until they are. It may take about 1/4 turn of the wheels to get the gears lined up. The clunk you hear is probably the gears engaging.

Two other things.

If you don't engage 4X4 and low range regularly the internals don't get lubricated, and it can make it harder to engage when you need it. I think the owner's manual suggests about 10 miles/month. I don't get in 10 miles every single month, and it doesn't say 10 miles at once. I engage 4X4 and low range every time I find myself on a gravel road. I may only get in a mile or 2 some months. Other months several hundred, and I may occasionally miss a month. But I won't miss 2 months. I haven't had any issues since making sure to do that.

Don't engage 4X4 on ground surfaces with good traction. This is what causes the gears to bind up and not want to release. While it would be rare to have a catastrophic parts failure it is certainly a possibility. You are more likely to see parts prematurely wearing out.

 

It's weird that it done it. It was only in and out of 4 lo. It works just fine going in and out of 4 hi. It wierd that it just started making that noise. I've used 4 lo multiple times and it never done it until yesterday. I can't really explain the noise it's like a grind/crunch like a gear is still spinning. Once it does it that one time going in and out and go in and out of 4lo as many times as I want and it never does again.