Jeep wrangler 4-wheel drive

My 4-wheel drive is not engaging immediately in my 1998 Jeep Wrangler. When it did engage, it made a loud noise while it was working. When I disengaged it, it continued in 4WD for a few minutes, then made a “thud” like I’d run over something (came from back passenger side) and then disengaged.



What’s wrong?

Can I still use 4WD without doing damage (more damage) to anything?

You should only engage the 4WD when on poor traction surfaces and immediately dissengage when approaching a high traction surface. What was the condition of the road you were on when this occured?

Rainy/slushy road - I needed it when turning onto a busier street from a side street. It was the beginning of a snowy, wintery mix in Cincinnati (lots of hills to climb) early in the AM before much traffic was out. I disengaged (or tried to) and then slid a bit going downhill a few minutes later (which could have happened in or out of 4WD).

My son has a 98 Wrangler with the same thud disengaging 4wd. There was debris caught up under the transmission (twigs, grass and stuff) that may have been messing up the linkage. We cleaned that out and the thud went away after a while. Not sure if there was a connection but it is worth getting under and checking it out.

Is is “easy” to find on the underside of the car, or do I have to take it in? What’s involved with “cleaning it out”? Where would I look? I’m mechanically-challenged… Thanks for the advice.