I've been trying to track down a grinding noise i'm experiencing when slowing down that (from what i've read here on yt) is likely the driveshaft or the transfer case. Basically, a couple times a week, i'll be decelerating at around 40mph in 3rd or 4th gear and i'll get this terrible, metal on metal grinding noise that seems like it's coming from the front half of the truck. There is no change to the noise if i push in the clutch or shift gears, and the intensity is directly related to my speed, and not the engine speed. However, if i shift into 4hi, i get a loud CLUNK and it goes away. I get this same CLUNK if i just slow down to about 5 mph, even if i don't shift the t-case. Also, this ONLY happens under deceleration, if i give it any gas at all, even just touching the pedal, it goes away until i let off again. It is NOT the spindle bushings, as i have already greased those. It seems like it would be something in the transfer case, but is this something semi-common? Any ideas what part could be causing this? Also, how can check the driveshaft? I can spin the driveshaft maybe 20 degrees before it stops. Thanks a lot for the help, guys, i really appreciate it!

 

grease thoes hubs son. assuming u have manual hubs.

 

you shouldn't be able to spin the driveshaft freely if the front hubs are unlocked.

sounds like that could be your problem...you shouldn't drive down the road with your hubs locked in..i did..and my front driveshaft sheered in half and busted my t-case and transmission and put a hole in the passenger side floor.

one way to check u-joints...if you can understand this..i'm not good at explaining stuff..i'm great at showing though lol

the u joint has 4 "points"

hold the driveshaft..and shake back and forth in the direction of those points..if there is ANY movement..then the u-joint is bad.


if that made any sense...then i'm happy LOL

 

Sorry, i should have specified, i meant that i can spin the REAR driveshaft 20 degrees. I'll have to check on the front one later today. I've also noticed that when i let out the clutch in reverse, i get a distinct metallic CLUNK or CHING each time i let out the clutch. Is that bad? Could that be related to bad u joints? Also, i have ADD hubs, so simply unlocking the front isn't an option until i have the cash for some manual hubs. Hopefully soon!

 

could the front end be trying to lock itself in? my brothers chevy had a noise that the garages could pin down. we put his truck on 4 heavy duty jack stands so we could run it in 2wd and 4 wd. it turned out to be a bad rear axle shaft. i used a piece of hose taped to a 8ft stick to listen to differant areas with out getting under the spinning wheels. the poor mans stethoscope worked well. just a suggestion.

 

Figured it out! The previous owner had mixed up a couple wires in the engine bay. The connectors for the emissions equipment and the little vacuum solenoids for the ADD system are the same (and same color) and he had hooked the emissions wires up to the ADD solenoids. Under certain engine conditions when the emissions system tried to send signals it would go the the vacuum solenoids, essentially trying to lock and unlock the front differential at the same time. It's probably been like that for the last 150,000 miles But problem fixed! Hasn't done it for at least 6 months since.

 

I would have never guessed that one ,glad you where able to fix it.

 

lol no doubt. lucky guy!