When I place my truck into 4hi everything engages fine and when the system is under torque either starting or stopping I get a clunk/clank that sounds like its coming from the transfer case. In 4lo it is worse, I think because of the excessive torque. When in the air with front and rear wheels spinning freely it makes the same noise as the wheels come to a stop as the torque is applied to the drivetrain, as you can see the parts move slightly - it makes the noise. My first thought was the transmission/transfer case mount, but I think it would do it in 2wd as well. Maybe the front u-joint? would I notice if it was binding? Chain in TC slipping? Please help.

 

With it in park get under it and turn the rear driveshaft right and left, do you hear the clunk? if so it is the chain in the transfer case,

 

X2 to papajim-but check all u-joints,CV shafts and hub bearings,these are possible culprits as well!

 

there is no play in the rear drive shaft and a little bit of play in the front. from what i have been reading i think it is the front u-joint. both cv axels are new and hubs are fine.

any ideas on how to check the front u-joint?

 

After investigation tonight it appears that the front diff is slightly disengaging when brakes or gas are pressed Essentially loosing vacuum. Now to find a damn vac leak. On a positive note it will fix my no floor all face heat problem haha.

Would bad intake gasket cause this bad of vacuum leak?

 

check all vacuum lines especially the one at the vacuum bulb. if they're brittle replace them. also look at the little vacuum check valves... be sure they're installed in the correct direction...

 

yeah thanks. i replaced alot of the the ones near the firewall ect. mine is a 2000 and it has the vacuum storage in the fender. Changed pvc check all lines there. need to double check diff vac line to diaphram next. I just want to drive this thing

 

also check the vac switch on the transfercase

 

i have the 4 button so mine is mounted on the firewall. i swapped it with a bone yard one but i need to see if it is holding vac

 

chain is skipping teeth inside TC. getting it swapped out for a good deal today. ugh