Hi everyone. I recently installed a rough country 4.5" lift (short arm kit with adjustable upper & lower control arms) into my '96 XJ. I have an NP242 transfer case. Last week I finished up the installation of the Advance Adapters slip yoke eliminator kit for the NP242. I was very thorough with the reinstall of the parts when I put the modified main shaft/front output shaft/chain assembly back into the transfer case.

I was also really careful about making sure that the oil pump pick-up tube was fully seated into the oil pump inlet, etc.

Ordered a custom length double cardan driveshaft from Tom Woods and got that in. What is happening currently is so damn discouraging; I have some kind of scraping/whirring noise coming from the transfer case. I know it's coming from the transfer case because I can hear it with both driveshafts disconnected and the engine just at idle with the transfer case in gear.

I admit that I put on the front yoke with my air impact wrench. But I wasn't using the highest forward drive setting or anything and the force didn't feel excessive. Does it seem like I could have actually damaged the front output shaft bearing from doing this?

Would there be any other obvious things I might check to hunt down the source of the noise?

Thank you in advance for any help you can provide!

 

I have a SYE with a Tom Wood DS on my NP231, and mine makes more noise than it used to. However, I'm pretty sure that's because I put on an Azzy's Design Works transfer case shift linkage at the same time, and that design tends to transmit more noise to the interior since it's a solid and direct connection. Try draining a little sample of fluid out of the transfer case. Do you see any sparkly metal shavings? If so, do they stick to a magnet?

 

Thank you very much for the reply. Tomorrow I will drain the case and inspect. Would I expect to see metal shavings in the fluid after just maybe 20 miles of test driving, do you think?

I tried to get a video from inside the Jeep of the sound. Both driveshafts are disconnected here:


There is always that chance that I'm just worrying about nothing, lol.

 

Did you adjust the transfer case shifter after doing the SYE? Does it quiet down if you move the lever a little in either direction?

 

I did not adjust it. Should I have?

Ah, I hadn't really tested that. I see where you're going with that and wish I had thought of that. I currently have the back case half off and am waiting on some Permatex automatic transmission gasket maker to come from Amazon. I'm going to try waiting a little bit longer than the instructions say before torqueing the bolts to spec to see if giving the gears just slightly more space will do the trick.

I'm thinking that I might have gotten the main rear case half and the tail cone housing a bit too tight.

Thank you for the reply! Seriously looking for any ideas.

 

@IJM : I got the case half back together. One thing I noticed in general was that my shifter inside the jeep was completely bottomed out against the very front of the shifter channel when in the 2WD position. What I did was I loosed the set screw/bolt under the Jeep and then just pulled the shifter in the cab back about 1/4".

This gave me room to actually test your theory of moving the shifter slightly up or down to see if the noise changes - and it does. The case is shifting well, and the noise is quieter than it had been before. I still would say it's there, but it seems like it's better. But here's a question (and this is with both driveshafts removed): the rear output yoke felt really hot after just like 10 minutes of being in 2WD and then transmission in drive in the garage.

Do you guys think I should be concerned about that? I just don't think there's any way that the oil pump pickup tube is not fully seated in the o-ring of the oil pump inlet. I made sure to be able to see the pickup tube being inside the pump inlet before I put the Advance Adapters tail housing cone back on (both times).

 

Glad to hear making some adjustments on the shifter seemed to quiet it down a bit. As for your second question, I don't know that I have a good answer, but I have noticed a hot/burning rubber smell after I've driven my Cherokee in 4HI and 50+ mph for a while when I was driving on snow-covered highways and back roads. I should have crawled under there at the time and felt for abnormally hot areas like you did, but I didn't feel like lying in the salty, slushy mess. I'm not sure if that's related, since it happened while I was in 4HI, but it was the first thing that popped into my head after reading your post.

Did you end up draining out any fluid to look for metal particles?

 

Keeping in mind that I really only put about 20 miles on it right after I installed the Advance Adapters slip yoke eliminator kit, yep, I did fish a magnet around through my drain pan when I drained the (fresh) fluid a couple days ago. There was basically nothing that stuck to the magnet. Honestly what I mainly saw in there were little slivers of gray RTV. There was probably a little bit of aluminum. I noticed that the Advance Adapters tail cone housing had tons of aluminum shavings in it. I did my best to blow it all out with an air compressor before the original install.

I think I forgot to mention this, but I also still have the Rough Country transfer case drop pucks installed. I left them installed so that it would make it so much easier to do the SYE install in the first place. I wonder how much of a chance there is that the noise lessens even more/goes away if I bring the transfer case crossmember back up to its factory position...

It's just so weird because I'm trying to remember if I heard this whirring sound right after I installed the lift & transfer case drop (but before the SYE install). I just don't think I heard a whirring sound as the transmission went into gear while the transfer case is in 2WD.