NP241 Transfer case. Clicking sound

[BoK5]

I have a 89' K5 Silverado Blazer 4-Wheel Drive Gas with an OHV 8V 350 cid engine and automatic transmission.
It has the standard transmission TH700-R4 and standard transfer case NP241(see pictures).


I have today started hearing a clicking sound when driving. Same sound as if a small stone is pressed into the tire.
Having the transmission in 'Neutral' and raised the vehicle in the back. I can hear the clicking sound, when I rotate(forward or backward) the tire. The clicking sound is coming from the transfer case to my best judgment.
Observing the rear drive-shaft when rotating the tire, I can hear the clicking sound two times, when the rear drive-shaft is turned 360 degrees.
The transfer case is correct filled with lubricate to the lower level of the filler hole (I have just checked).

Yesterday I had pulled and pushed the speedo cable to be able to remove and install the instrument cluster again.


Anyone experienced same problem or having an idea to, what is causing the problem.

 

[Mr.Chevy4x4]

There are hard plastic "sliders" on the shift forks that eventually wear out. This can allow the shift collar to move and allow the synchronizers or gears to slightly touch. I've had this happen before and cause clicking sounds and gear wear. Not sure this is your issue, but a possibility.

Mike

 

[riflerk20]

did it happen after you unhooked your speedometer ? I've had clicking noises before a speedo cable broke or was hooked up wrong.

 

[BoK5]

Thanks for input.
Answer to riflerk20:
I had detached the speedo cable from the guage in instrument cluster and attached again. I have not detached the speedo cable from the transfer case.
It was just after this operation I heard the clicking sound.
I have tried shifting 2H to 4H to 4L and back to 2H everthing works smoothly.

Bo

 

[jeff in co]

Try disconnecting the speedo at your t-case and see if you still hear the noise. Maybe the cable somehow is pushing in too far and hitting the gear teeth inside?!?

 

[evolve991]

Not to scare you but I had some clicking noises in my old TC. Not long after I was stopping kinda hard at a red light and felt the CLUNK of locking into 4 Low. Dont know what was going on inside but the linkage got sloppy and I had to wire it to keep it in 2 High. I never figured it out I just swapped in an 89 241 I had.
Sorry to leave a cryptic mystery answer but I wanted to warn you about the possibilty of a cataclysmic gear drop. Hopefully it's a simple fix

 

[number_juan]

Don't forget the basics, it could very well just be bad u-joints. Our mills are old enough and the u-joints are cheap enough to replace. Just something else to think about.

 

[evolve991]

Don't forget the basics, it could very well just be bad u-joints. Our mills are old enough and the u-joints are cheap enough to replace. Just something else to think about.

Yeah,better than my solution And do not try to save a buck with u joints, get Moog or Dana/Spicer or an equivalent. It's worth it.