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NP242 in full time 4wd noise went away?

M

md21722

NAXJA Forum User
Location
TN
Hey All,

We've got the first real winter blast since I got my 97 XJ with the NP242.

I put it in full time 4WD a few days ago and left it there.

When I first put it in and out accelerate from a stop, I would get what I thought was chain or gear noise. Not slapping the case.

After the first 50-80 miles the noise has pretty much gone away and things are much quieter.

Any ideas what may have shifted or moved around inside or cleaned itself out?

I put a SYE in back in September and at that time the insides looked good. I could not identify any real chain slack and put the original chain back in. All that was changed was the front output bearing and rear output bearing. The rear was changed because the SYE came with a new output housing including the bearing and seal.
 
The front end seems to pull just fine. I have not raised the vehicle and put it in drive to see.

The motor and trans mounts are a couple of months old. They are dealer mounts and appear in perfect condition.
 
It could have just been a bearing in the transfercase that hadn't been spun in a while just grumbling before it lubed up and reseated itself...
 
I think the linkage needs adjustment. It is kind of difficult to get it back in 2wd after its been in 4Hi/4Full time. I will take a look. Since 4 Full time is smack in the middle of the selector and seems to be selected very easily, I'm pretty sure its fully engaged.

I also noticed that when in 4 Full Time, when I put it in reverse and start backing up (think off brake pedal, in parking spot) that it will clunk or bang one time.

I have no idea what inside the transfer case would cause this.

Could it be that the transfer case differential is somehow causing these issues?
 
md21722 said:
The motor and trans mounts are a couple of months old. They are dealer mounts and appear in perfect condition.
Click to expand...
Maybe someone readjusted the linkage before you replaced the mounts???
 
I'd guess the linkage is a bit off because the Jeep had a transfer case drop when I bought it and I replaced it with a SYE. But I'm not sure how that would affect Full Time 4WD since its in the middle of the selector. I think its why its a bit difficult to get it in the 2WD again.
 
I took the linkage apart today. Based on how hard it was to get the rods out of the bushings I'd say they were in good shape. But I found that someone had been in there before and put a drop plate, probably when they did the transfer case drop. They also sheared off the bolt that holds the adjuster in place and bent the adjuster shaft. I had a linkage repair kit on hand for my other XJ that I haven't installed yet, so I'm putting that in and will adjust once I get a replacement adjuster. Is there any harm in leaving the transfer case in 4x4 Full Time mode without any linkage holding it there?
 
Make sure the shifter itself moves nice and free. W/o the linkage attached it should move very easily.

Which linkage repair kit did you go with? If its a Crown kit let me know how you do with those bushings. The ones I recently used were too hard and just broke.
 
It's all back together. The existing bushings were still holding the rods in the linkage arms very tight. It is not easy to get the arms or the bushings out and back in. I'm not sure what kind of pliers would help given the limited room. A socket on the receiving end and some pliers may help. I lubed up the rod ends with sliding fluid and use a pry bar. Lubed up the bushings with sliding fluid and push them in with pliers. I would not try to put any of this back together without using some type of sliding fluid. Spray silicone may help in place of the sliding fluid. The shifter now moves very freely through all positions.

I used the dealer kit which includes the bushings, swivel joint, and a spring loaded rubber boot and rubber receiver. The rubber boot and receiver would keep the swivel joint clean but its not possible to use these pieces unless you take the bracket off the transfer case or loosen the mount to the frame.

Dealer part number 501 4148 AB

And special thanks to Frank Z for helping me out with the shifter rod.
 
I occasionally get gear noise when engaging 4WD on the street after I haven't for a while that goes away after a couple dozen miles - I always attributed it to the front axle being used to driving on the coast side of the gears that now has to run on the drive side.
 
I have a one quart jug of Mercedes sliding fluid. I bought it years ago when I was wrenching on their diesels. I always thought there was some domestic equivalent. Basically its used on rubber where grease might degrade the rubber. Its a thin, milky white fluid that makes pressing stuff like this pretty easy. Since these shifter bushings seem more like hard plastic than rubber I bet grease is just fine but since I have the sliding fluid I used it.
 
Updating this thread.

Last weekend I hit snow and ice in the mountains and used Full Time. When I let off the gas I heard a one second zing type noise. That's the only noise the transfer case has made in some time.

I opened the case this weekend to check it out related to a humming noise and some metal flakes in the fluid that were about <= 0.5mm. I found that the oil pump seal was dislodged and there was a groove in it as well as the pump. I think it was wearing against the main shaft. When I put the SYE in two months ago I put RTV in the same places as I saw when I took it off. When I put the SYE in I saw the oil seal was hard and missing a few pieces. I believe this was because RTV was put around the metal tabs on the pump. I think the RTV gets between the pump tabs and housing and causes the pump to run on an angle.

When I install it again, I will be sure not to put RTV around the tabs!

It also tells me that that the chain was probably replaced at least once before.
 
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