Noise when engaging 4H from 2WD

[s1moore1s]

Over the weekend I engaged 4H from 2wd at about 30 mph. I heard a fairly loud noise come from beneath the truck then the dash showed I was in 4H. I've done this several times but don't ever remember hearing this noise. Is this normal? Thanks.

PS
04 Sport V6, 229k miles

 

[scottm]

Not normal, how long since you changed the fluid in your transfer case and differentials? It might be wise to do so and strain it through a paint filter or cloth looking for metal bits. Or maybe drain it into a clean container and roll a magnet around in it to search for metal bits. No magnet on the drain on my transfer case when I changed it weeks ago, but magnets on the differential drains. Have you engaged it since and did it sound normal? Was it a single loud clank, or a grinding noise?

 

[s1moore1s]

I believe it was a loud clank, I'll try again. The transfer case and differential fluid have all been changed within the last 6 months.

 

[scottm]

I have heard a clank when engaging on other vehicles that are normally quiet, that wouldn't worry me so much. Perhaps you had the relative speeds just right or it bound just a little. I'd be more worried about grinding, screeching, mooing, clucking,...sounds that are more ominous or difficult to explain.