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85 K20 4WD problem

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dneiding

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Recently my 85 K20 has been making a clucking noise in the front end when in 4WD. The frequency of the clunk, clunk, clunk is the same as the wheel speed. Just this week, while plowing my drive way, the clunks got louder and there were a few jarring clunks. At one point it seemed as if the front wheel was locked up.

In order to keep going I had to take it out of 4WD AND unlock the hubs.

I did some driving last night up and down the road to see what might be going on and I found that
- with the hubs UNLOCKED and it in 4WD (both hi and low) I have no noise and no problem
- with the hubs LOCKED and driving in a straight line there is a bit of clunking noise but not much
- with the hubs LOCKED and turning the wheel there is tons of noise, jarring clunking and the front wheels seem to lock up; this is with the transfer case in 4WD or 2WD...if the hubs are locked and I turn the wheel things don't go good, 4WD or 2WD both act the same.

So does this seem to be a differential problem or a problem with the hubs? Doesn't sound like a transfer case problem does it?

I haven't taken off the differential cover yet (I will this weekend) but I was just looking for some initial opinions on what might be going on.

Thanks in advance!!!
 
Sounds like an axle u-joint is either seizing up or more likely has lost all its needle bearings and is flopping around on the journals--easy enough to check by trying to twist the outer part of the axle where it goes into the rotor while holding the other side of the axle still..sometimes you wont see anything wrong till you take the u-joint out though...another possibility is your front driveshaft might have sloppy splines on the slip yoke,under power only they'll sound like a bulldozer that has bad sprockets and tracks--clunk,clunk,clunk,,thats "timed" with each revolution the wheels make...when there is no load on the shaft it is usually quiet or less noticeable...could be a bad u-joint in the front shaft or the CV joint ball is worn out too...

I'd think if it were differential troubles you'd hear clunking anytime its hubs are locked in,whether your in 4wd or not,as the axles turn the gears when the hubs are locked in..
 
diesel4me said:
Sounds like an axle u-joint is either seizing up or more likely has lost all its needle bearings and is flopping around on the journals--easy enough to check by trying to twist the outer part of the axle where it goes into the rotor while holding the other side of the axle still..sometimes you wont see anything wrong till you take the u-joint out though...another possibility is your front driveshaft might have sloppy splines on the slip yoke,under power only they'll sound like a bulldozer that has bad sprockets and tracks--clunk,clunk,clunk,,thats "timed" with each revolution the wheels make...when there is no load on the shaft it is usually quiet or less noticeable...could be a bad u-joint in the front shaft or the CV joint ball is worn out too...

I'd think if it were differential troubles you'd hear clunking anytime its hubs are locked in,whether your in 4wd or not,as the axles turn the gears when the hubs are locked in..
Click to expand...

Well a u-joint would be an easy fix. I'll take a look at that first.

Thanks!
 
Wouldn't a u-joint bind when turning with the hubs locked or unlocked? Mine only binds and makes noise when the hubs are locked - all is fine when they are unlocked.
 
dneiding said:
Wouldn't a u-joint bind when turning with the hubs locked or unlocked? Mine only binds and makes noise when the hubs are locked - all is fine when they are unlocked.
Click to expand...

On an older truck with manual hubs no-hubs unlocked u joint does not spin, on a newer unit bearing equipped truck yes.
 
Yep, the passenger-side u-joint is a mess. Broke the ears off of the axle shaft too. Looks like I got my weekend planned out for me :(
 
by the sound he prob dont know. and only millitary m-1031 and m-1028 got limited slip front. unless otherwise added to the truck.
 
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