weird road noise and clanging

[hawkeye213]

Alright you have the normal road noise ( tires on the pavement )the last week or so I have what I can only describe as the same road noise but it is just louder. It sounds like it is coming from the front center of the truck As you accelerate it gets louder. I finally got the boat out for the first time this year and pulled it to the lake. The ramp is unbelievably steep so I just put it in 4wd to drive up the hill. As I am going up the hill I hear what I think is the safety chain bouncing up and hitting the frame of the trailer. I go fishing and then put the boat back on the trailer put it in 4wd and start to hear the clanging again Get up to the top of ramp and realize it's my truck making the noise. I take it out of 4wd and it stops. Put it back in 4wd and turn the wheel and slow rate of speed and the clanging seems to get worse. I looked at all the U joints and checked all my fluids and everything looks alright. As I drove home from the lake I was thinking the loud road noise and the clanging in four wheel drive must be connected. It doesn't make any noise when turning the steering wheel in 2wd. The steering is tight and straight down the road. I used the 4wd earlier in the winter and had no problem. Any thoughts on where to start ? Maybe a u-joint going bad ?Thanks Rob

[dripley]

I dont know alot about the transfere case, but it sounds like the chain in it is banging around. Saw a few posts on here lately.

[Rogan]

First, I'd check the cardan joint on the front DS. When they go bad, they 'generally' sound like angry sparrows fighting under the truck. What generally happens (as I've experienced in the past) is that they usually get overlooked when the grease gun is used, due to them needing a needle-point style tip to grease. They dry out, then sometimes the spring breaks inside, falls out, and gets sloppy, then binds.

As for the tcase, the 241 isn't a lot different than the NP231s, in respect to design, however the 241 is definitely bigger/heavier/beefier.

Here's the chain layout inside the 24x tcases:

This is from a 243 (push button electric) tcase tear-down. The 241 is identical inside. Only difference between the 241 and 243 is the electric actuator vs manual lever.

http://smg.photobucket.com/albums/v35/hquick/NP243%20rebuild/

[mr.mindless]

from your description the tcase is the first thing I'd be looking at.

[Rogan]

from your description the tcase is the first thing I'd be looking at.

I agree on the tcase.

If your chain has stretched, it could very well be slapping the inside of the case.

The tcase removal is fairly easy and straight-forward.. remove skidplates if present. 6 nuts (on studs) hold the tcase to the trans. remove the driveshafts, the tcase shifter linkage, vacuum lines and connectors, and 6 nuts on the transmission-side of the tcase. (place a trans jack or equivalent under the tcase and apply a touch of pressure, but very little on it. once all is ready, gently slide the tcase backward to disengage the studs from the trans. lower tcase, and place it on a sturdy work surface. Then get busy!

you may lose some trans fluid (possible, but not likely.)

may as well replace any seals leaking (best to replace the front output seal at this time) and pick up a tube/can of Permatex Right Stuff gasket maker; get the gray kind.

Use that to seal the tcase halves together when reassembling..

Oh, and you'll need an assortment of snap-ring pliers, of various sizes/strengths. You'll need a fairly heavy-duty set, as well.

Transfer cases, in general, are quite simplistic in design.

[mr.mindless]

FYI if you leave it be, a slack chain can wear through the aluminum housing and cause you more issues like burning up bearings and having to replace or patch the case itself...

diagnostic: check how much slop exists between front and rear outputs when in 4x4. Possibly tough to judge without experience to know what to expect as far as normal vs excessive play, but if it's really sloppy, you'll know it... Be sure the front shaft is turns free on the axle end so you don't have a false test, you may need to remove it depending on how well your CAD behaves disengagement-wise.

[KATOOM]

Before you go tearing anything apart, you need to know a few things first. Like if you have the CAD front axle or not. The CAD unit is obvious to identify by the large collar looking section which would be on the passenger side of the front axle housing, with a couple vacuum hoses and a couple electrical lines coming off of it. Its rare for '02 trucks to have the CAD but if you have this then I'd start with jacking the front axle off the ground and checking the front wheel bearings for excessive play which may indicate a bad front bearing.If you do NOT have the CAD front axle whereby your front axle housing looks completely normal then your 4wd system is full time which means the front driveshaft spins all the time. This also means that if there was anything wrong in the TC then you would certainly hear it make strange noises all the time since the front driveshaft is spinning the TC output shaft all the time. This by no means is me saying not to pull the TC fill plug either and check to see if any of the TC lube has escaped without notice or that the lube doesn't look murky or have metal in it.If the TC lube looks fine then the chances of anything being wrong in there is slim to none. At that point, I'd start looking at the front driveshaft. The non-CAD front driveshafts are notorious for wearing out u-joints and the double cardan unit too. As mentioned by Rogan, when those go bad then you can experience noises and vibrations. An indication would be a slight fast paced harmonic vibration you may feel under the truck as you drive down the road.

[hawkeye213]

Sorry for starting this thread and then bailing. Anyway got under there tonite and jacked the front end up and gave the wheels a spin and could immediately hear a noise go to looking around and the u-joint from the tcase to front drive shaft is shot. It is hidden by the skid plate. Removed drive shaft will take to the machine shop tomorrow get some new ones pressed in. Hopefully that will solve everything. If not I'll be back Thanks Rob