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loud "thud" from driveshaft?

okay I'm a newb here but I'll do the best I can b/c I'm loosing a fair amount of sleep here. $$ is an issue and I want to fix this thing as cheapy as possible, so guessing in the right direction is important.

which seal is it? - my mechanic calls it the "rear output seal" it leaks where the driveshaft plugs into the t-case. It leaked befor the problem, I had the seal replaced, and it continued to leak.

I just thought of ANOTHER clue. One day when it was about 10 degrees outside I got in the truck, started it, warmed it up, put in drive and it did not move, gave it a little gas - still did not move. I got out and looked under all of the tires and nothing was there, so i got back in, put in drive and gave it a little more gas - "BANG". The it drove like usual. It was a pretty big noise that scared the **** out of me! Befor this incident the trucvk never had this noise - it was in the weeks after this that the noise started.
Thanks for everyone's help - I appreciate your time on this thing!
 
technician A says:

is there any play in that output shaft, if you grab it and try to rock it up and down can you feel any movement. Rock the truck back and forth and look for any movement at that yoke. there should be none.

also- try to find out what your drivetrain is- axle ratios, axles, tcase, trans.
the loud bang you heard that day- when it banged did it suddenly jerk or did it slowly move after that.
how does the t-case shift- is it normal, or is it hard to engage 4wd. also try putting the truck on jackstands (all 4 wheels) and putting the truck in gear with your foot lightly on the brake for a visual of everything working correctly, sometime when you take the load off the components the noises will be more obvious, sometimes they won't.
 
red77blazer said:
is there any play in that output shaft, if you grab it and try to rock it up and down can you feel any movement. Rock the truck back and forth and look for any movement at that yoke. there should be none.

also- try to find out what your drivetrain is- axle ratios, axles, tcase, trans.
the loud bang you heard that day- when it banged did it suddenly jerk or did it slowly move after that.
how does the t-case shift- is it normal, or is it hard to engage 4wd. also try putting the truck on jackstands (all 4 wheels) and putting the truck in gear with your foot lightly on the brake for a visual of everything working correctly, sometime when you take the load off the components the noises will be more obvious, sometimes they won't.

shaft seems pretty firm - I tried to move it befor i put it in the shop. My mechanic told me today (once again) that he has owned a few of these trucks and everyine that he had ever driven that has a lift does this and "that's the nature of the beast and You'll just have to live with it" well, that's not cutting it for me! I bought this thing for fun and it's NOT FUN to hear that freaking noise all day and know that I tearing up my baby! Anyway it's not in my driveway right now so i can not answer all of the questions, when I get it back I'll look into that other stuff.

When i get her back - this week sometime - I'll get back to ya'll with what I can figure out. Thanks
 
no prob-tell your mechanic this nechanic says he should know trucks don't start making noise because they are lifted, thats a bunch of bs. I have been wrenchin a while and my truck got lifted 7" and yes it started making noises like that, but there is diagnosis, and its mighty useful, i would not give up or take it to someone who says that its just the way it is.


When you get more info pm me and post it, you'll find it, thats the fun part about k5 repairs,
 
okay. got fed up with my mech when he said that he could def fix the problem by rebuilding tcase and adding new springs in the back! I'd rather spend some time figuring out what the problem is and addressing it. So when I get it back I'll think this over again. do you think that pulling the driveshaft and having it lengthened will help? also I think I can get the slip yolk built onto the shaft - rather than in the t case where it is now, no?
 
You can get the slip yoke built into the shaft if you have NP241 which will require a slip yoke eliminator kit($$$). The NP203 and 205 should already have slip yokes in the shaft behind them?? If you have a NP208 you don't really have that option that I am aware of. Your transfer case should have a stamp on it with the model number, that would help some to know what were working with.
 
stallion85 said:
You can get the slip yoke built into the shaft if you have NP241 which will require a slip yoke eliminator kit($$$). The NP203 and 205 should already have slip yokes in the shaft behind them?? If you have a NP208 you don't really have that option that I am aware of. Your transfer case should have a stamp on it with the model number, that would help some to know what were working with.

It's a np205 I believe but I'll have another look today. Just got it from my mech and it sounds MUCH better - not that he did anything. I can still feel a little "movement" in the driveshaft but nothing even close to the way it used to be. strange. I'll have time ti investigate more tomorrow.
 
Could be several items or a combination:

Your profile states you have an 86, so the t-case should be a 208. The chain only comes into play in 4wd so that should not be an issue. It also says you run a 6" lift, so it could be slip shaft bind.

Other possible causes:

Motor mounts worn out
T-case mounts worn out
Range selector collar in the t-case worn out (or associated teeth on the meshing gears)
Locker "lash"
Worn pinion bearings
Worn u-joints
Cracked flywheel (not likely though)
Leave spring bind/loose clamps/loose u-bolts
 
There are a few more things that it might be. I just read your post about the sticking one day and then the bang......

I am actually going to be in Atlanta next week (Sun-Fri) for training. I would be willing to take a look if you could bring it to me or pick me up after class. I will be:

TO RESIDENCE INN: Take I85 North to GA400 Buckhead/Cumming.
There is a toll. Currently, it is 50 cents.
Exit at number 9 Haynes Bridge Rd. and turn right.
Turn right at North Point Dr. Residence Inn is on your right.


If you are interested send me a PM.

P.S. Any of GA CK5ers who want to meet, I will have nothing to do as I did not opt for a rental car this trip. I will be free Sun-Thurs nights and flying out Friday afternoon.
 
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